Power management of transponders and sensors in an RFID security network

CROSS REFERENCE TO RELATED APPLICATIONS

0001This patent application is a continuation-in-part of U.S. application Ser. No. 10/821,938, Cordless Telephone System, filed Apr. 12, 2004 by the inventor of the present application, which is itself a continuation-in-part of U.S. application Ser. No. 10/795,368, Multi-Controller Security Network, filed Mar. 9, 2004, which is itself a continuation-in-part of U.S. application Ser. No. 10/602,854, RFID Reader for a Security Network, filed Jun. 25, 2003 (now allowed), which is itself a continuation-in-part of U.S. application Ser. No. 10/423,887, RFID Based Security Network, filed Apr. 28, 2003 (now allowed), which is itself a continuation-in-part of U.S. application Ser. No. 10/366,316, RFID Reader for a Security System, filed Feb. 14, 2003, which is itself a continuation-in-part of U.S. application Ser. No. 10/356,512, RFID Based Security System, filed Feb. 3, 2003 and issued as U.S. Pat. No. 6,888,459.

0002This patent application is further cross referenced to the following patent applications: U.S. application Ser. No. 10/820,804, Configuration Program for a Security System, filed Apr. 9, 2004; and U.S. application Ser. No. 10/806,371, Communications Architecture for a Security Network, filed Mar. 23, 2004; and to the following patent applications, all filed Feb. 14, 2003: U.S. application Ser. No. 10/366,320, Communications Control in a Security System; U.S. application Ser. No. 10/366,335, Device Enrollment in a Security System; U.S. application Ser. No. 10/366,334, Controller for a Security System (now allowed); and U.S. application Ser. No. 10/366,317, RFID Transponder for a Security System; and to the following patent applications, all filed concurrently with the present application by the inventor of the present application: “Clip for RFID Transponder of a Security Network,” “Component Diversity in an RFID Security Network,” “Portable Telephone in a Security Network,” “Multi-Level Meshed Security Network,” and “Fixed Part-Portable Part Communications Network for a Security Network.” All of the foregoing cross-referenced patent applications are incorporated by reference into this present patent application.

TECHNICAL FIELD

0003The present invention relates generally to security networks and, more particularly, to an apparatus and a method for managing power in the RFID transponders and sensors of such a security network.

BACKGROUND OF THE INVENTION

0004Security systems and home automation networks are described in numerous patents, and have been in prevalent use for over 40 years. In the United States, there are over 14 million security systems in residential homes alone. The vast majority of these systems are hardwired systems, meaning the keypad, system controller, and various intrusion sensors are wired to each other. These systems are easy to install when a home is first being constructed and access to the interiors of walls is easy; however, the cost increases substantially when wires must be added to an existing home. On average, the security industry charges approximately $75 per opening (i.e., window or door) to install a wired intrusion sensor (such as a magnet and reed switch), where most of this cost is due to the labor of drilling holes and running wires to each opening. For this reason, most homeowners only monitor a small portion of their openings. This is paradoxical because most homeowners actually want security systems to cover their entire home.

0005In order to induce a homeowner to install a security system, many security companies will underwrite a portion of the costs of installing a security system. Therefore, if the cost of installation were $1,500, the security company may only charge $500 and then require the homeowner to sign a multi-year contract with monthly fees. The security company then recovers its investment over time. Interestingly enough, if a homeowner wants to purchase a more complete security system, the revenue to the security company and the actual cost of installation generally rise in lockstep, keeping the approximate $1,000 investment constant. This actually leads to a disincentive for security companies to install more complete systems—it uses up more technician time without generating a higher monthly contract or more upfront profit. Furthermore, spending more time installing a more complete system for one customer reduces the total number of systems that any given technician can install per year, thereby reducing the number of monitoring contracts that the security company obtains per year.

0006In order to reduce the labor costs of installing wired systems into existing homes, wireless security systems have been developed in the last 10 to 20 years. These systems use RF communications for at least a portion of the keypads and intrusion sensors. Typically, a transceiver is installed in a central location in the home. Then, each opening is outfitted with an intrusion sensor connected to a small battery powered transmitter. The initial cost of the wireless system can range from $25 to $50 for each transmitter, plus the cost of the centrally located transceiver. This may seem less than the cost of a wired system, but in fact the opposite is true over a longer time horizon. Wireless security systems have demonstrated lower reliability than wired systems, leading to higher service and maintenance costs. For example, each transmitter contains a battery that drains over time (perhaps only a year or two), requiring a service call to replace the battery. Further, in larger houses, some of the windows and doors may be an extended distance from the centrally located transceiver, causing the wireless communications to intermittently fade out. In fact, the UL standard for wireless security systems allows wireless messages to be missed for up to 12 hours before considering the missed messages to be a problem. This implies an allowable error rate of 91%, assuming a once per hour supervisory rate.

0007These types of wireless security systems generally operate under 47 C.F.R. 15.231 (a), which places limits on the amount of power that can be transmitted. For example, at 433 MHz, used by the wireless transmitters of one manufacturer, an average field strength of only 11 mV/m is permitted at 3 meters (equivalent to approximately 36 microwatts). At 345 MHz, used by the wireless transmitters of another manufacturer, an average field strength of only 7.3 mV/m is permitted at 3 meters (equivalent to approximately 16 microwatts). Control or supervisory transmissions are only permitted once per hour, with a duration not to exceed one second. If these same transmitters wish to transmit data under 47 C.F.R. 15.231 (e), the average field strengths at 345 and 433 MHz are reduced to 2.9 and 4.4 mV/m, respectively. The current challenges of using these methods of transmission are discussed in various patents, including U.S. Pat. Nos. 6,087,933, 6,137,402, 6,229,997, 6,288,639, and 6,294,992.

0008In either wired or wireless prior art security systems, additional sensors such as glass breakage sensors or motion sensors are an additional cost beyond a system with only intrusion sensors. Each glass breakage or motion sensor can cost $30 to $50 or more, not counting the labor cost of running wires from the alarm panel to these sensors. In the case of wireless security systems, the glass breakage or motion sensor can also be wireless, but then these sensors suffer from the same drawback as the transmitters used for intrusion sensing—they are battery powered and therefore require periodic servicing to replace the batteries and possible reprogramming in the event of memory loss.

0009Because existing wireless security systems are not reliable and wired security systems are difficult to install, many homeowners forego self-installation of security systems and either call professionals or do without. It is interesting to note that, based upon the rapid growth of home improvement chains such as Home Depot and Lowe's, there is a large market of do-it-yourself homeowners that will attempt carpentry, plumbing, and tile—but not security. There is, therefore, an established need for a security system that is both reliable and capable of being installed by the average homeowner.

0010Regardless of whether a present wired or wireless security system has been installed by a security company or self-installed, almost all present security systems are capable of only monitoring the house for intrusion, fire, or smoke. These investments are technology limited to a substantially single purpose. There would be a significant advantage to the homeowner if the security system were also capable of supporting additional home automation and lifestyle enhancing functions. There is, therefore, an apparent need for a security system that is actually a network of devices serving many functions in the home. It is therefore an object of the present invention to provide security system for use in residential and commercial buildings that can be self-installed or installed by professionals at much lower cost than present systems.

0011More specific objects of the present invention are directed to the transponder and sensor of the security network. A main object of the present invention is to manage the power used by the transponder and sensor. Another object is to enable smaller dimensions for the transponder and sensor while offering two-way communication. A related object is to enhance the reliability of the security network. Still another object is to conserve power (e.g., battery life) in the transponder and to avoid the need to insert or replace batteries in the transponder.

0012It is still another object of the present invention to provide a transponder and sensor that can be manufactured frugally yet have an active rather than passive nature. An additional object is to conserve processor time and current in the transponder. Yet another object of this invention is to avoid waste of power. Still another object is to enable the network to report wireless coverage.

0013Additional objects and advantages of this invention will be apparent from the following detailed description.

BRIEF SUMMARY OF THE INVENTION

0014To achieve these and other objects, and in view of its purposes, the present invention provides a highly reliable system and method for constructing a security network, or security system, for a building. The invention comprises a network of devices and uses a novel approach to designing base units and transponders to provide the radio link between each of a number of openings and a controller function capable of causing an alert in the event of an intrusion. Some forms of the present invention may also provide cordless telephone functionality and may further be packaged in an embodiment familiar to many end users as a cordless telephone system.

0015The present invention improves upon the traditional system model and paradigm by providing a security network with reliability exceeding that of existing wireless security systems, at lower cost than either professionally installed hardwired systems or wireless security systems. The present invention also allows self-installation, including incremental expansion, by typical homeowners targeted by the major home improvement and electronics retail chains.

0016Several new marketing opportunities are created for a security network that are otherwise unavailable in the market today. First, for professional systems sold by major alarm companies, a single customer service representative may sell the network to a homeowner and then install the network in a single visit to the customer's home. This is in contrast to the present model where a salesperson sells the system and then an installer must return at a later date to drill holes, pull wires, and otherwise install the system. Second, there is a product upgrade available for existing systems whereby the scope of security coverage can be increased by adding base units and transponders to an existing control panel. Third, homeowners may purchase the inventive system at a home improvement chain, self-install the system, and contract for alarm monitoring from an alarm services company. The overall system cost is lower, and the alarm services company is not required to underwrite initial installation costs, as is presently done today. Therefore, the alarm services company can offer monitoring services at substantially lower prices. Fourth, a new market for apartment dwellers opens up. Presently, very few security systems are installed in apartments because building owners are unwilling to permit the drilling of holes and installation of permanent systems. Apartment dwellers are also more transient than homeowners and therefore most apartment dwellers and alarm service companies are unwilling to underwrite the cost of these systems anyway. The inventive system is not permanent, nor is drilling holes for hardwiring required. Therefore, an apartment dweller can purchase the inventive security network, use it in one apartment, and then unplug and move the network to another apartment later.

0017The improvements provided by the present invention are accomplished through the following innovations. The first innovation is the design of a low cost base unit that can cover an area of a house. Rather than rely on the single centrally located transceiver approach of existing unreliable wireless security systems, the present invention allows the placement of multiple base units into multiple rooms and areas for which coverage is desired. The presence of multiple base units within a building provides spatial receiver diversity.

0018The second innovation is the use of different types of transponders to transmit data from covered openings and sensors. One transponder may use backscatter modulation. Another transponder may use low power RF communications (i.e., an active transmitter).

0019The third innovation is the permitted use of multiple distributed controller functions in the security network. In the present invention, the controller function can be located within any physical embodiment of a base unit. Therefore, a homeowner or building owner installing multiple base units will also simultaneously be installing multiple controller functions. The controller functions operate in a redundant mode with each other. Therefore, if an intruder discovers and disables a single base unit containing a controller function, the intruder may still be detected by any of the remaining installed base units containing controller functions.

0020The fourth innovation is the optional inclusion of a glass breakage or motion sensor into the base unit. In many applications, a base unit will likely be installed into multiple rooms of a house. Rather than require a separate glass breakage or motion sensor as in prior art security systems, a form of the base unit includes a glass breakage or motion sensor within the same integrated package, providing a further reduction in overall system cost when compared to prior art systems.

0021The fifth innovation is the permitted optional use of the traditional public switched telephone network (i.e., PSTN—the standard home phone line), the integrated use of a commercial mobile radio service (CMRS) such as a TDMA, GSM, or CDMA wireless network, or the use of a broadband internet network via Ethernet or WiFi connection for causing an alert at an emergency response agency such as an alarm service company. In particular, the use of a CMRS network provides a higher level of security, and a further ease of installation. The higher level of security results from (i) reduced susceptibility of the security system to cuts in the wires of a PSTN connection, and (ii) optional use of messaging between the security system and an emergency response agency such that any break in the messaging will in itself cause an alert.

0022The sixth innovation is an RFID transponder with an associated sensor used in a security network including at least one RFID reader that transmits signals at a first frequency. The transponder has a processor controlling its other components. Transmitter circuitry coupled to a transmit antenna transmits signals to the reader at a second frequency. A receive antenna receives signals in a frequency band that includes the first frequency. One or more RF diodes obtain the signal from the receive antenna and output a power envelope signal representing the power level of the signal obtained from the receive antenna. An amplifier coupled to the output of the RF diode amplifies the power envelope signal received from the RF diode. The processor receives the amplified power envelope signal and decodes any data that have been encoded using an on-off keyed modulation scheme applied to the signal obtained from the receive antenna.

0023The sixth innovation also encompasses a method for managing the power requirements of an RFID transponder having an associated sensor and being configured for use in a security network including at least a first RFID reader. The method includes the following steps: (a) sending signals from the RFID transponder to the first RFID reader at a second frequency representing relatively low power; (b) receiving return signals from the first RFID reader at a first frequency representing relatively high power; (c) transmitting the return signals to at least one diode of the RFID transponder; and (d) applying a combined on-off keyed modulation and amplitude modulation scheme to the signal obtained by the diode.

0024It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.

BRIEF DESCRIPTION OF THE DRAWING

0025The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following figures:

0026<figref idref="DRAWINGS">FIG. 1</figref> shows a base unit communicating with transponders.

0027<figref idref="DRAWINGS">FIG. 2</figref> shows an example security network formed with multiple base units and transponders.

0028<figref idref="DRAWINGS">FIG. 3</figref> shows an architecture of the base unit.

0029<figref idref="DRAWINGS">FIG. 4</figref> shows an example security network formed with multiple base units and transponders. Various example physical embodiments of base units are shown.

0030<figref idref="DRAWINGS">FIG. 5</figref> shows a generalized network architecture of the security network. Various example forms of base units are shown, where some base units have included optional functionality.

0031<figref idref="DRAWINGS">FIG. 6</figref> shows the distributed manner in which the present invention could be installed into an example house.

0032<figref idref="DRAWINGS">FIG. 7</figref> shows multiple ways in which a gateway can be configured to reach different private and external networks.

0033<figref idref="DRAWINGS">FIG. 8</figref> shows some of the multiple ways in which a gateway can be configured to reach emergency response agencies and other terminals.

0034<figref idref="DRAWINGS">FIG. 9</figref> shows control functions in multiple base units logically connecting to each other. One control function has been designated the master controller.

0035<figref idref="DRAWINGS">FIG. 10</figref> shows an example layout of a house with multiple base units, and the manner in which the base units may form a network to use wireless communications to reach a gateway.

0036<figref idref="DRAWINGS">FIG. 11</figref> shows an example architecture of a passive transponder.

0037<figref idref="DRAWINGS">FIG. 12</figref> is a flow chart for a method of providing a remote monitoring function.

0038<figref idref="DRAWINGS">FIG. 13</figref> shows an example embodiment of a wall mounted base unit in approximate proportion to a standard power outlet.

0039<figref idref="DRAWINGS">FIGS. 14A and 14B</figref> show alternate forms of a passive infrared sensor that may be used with the security system.

0040<figref idref="DRAWINGS">FIG. 15</figref> shows example embodiments of a smoke detector and a smoke detector collar into which an optional base unit or an optional transponder has been integrated.

0041<figref idref="DRAWINGS">FIG. 16</figref> shows some of the multiple networks in which a gateway can be configured to reach a remote processor or server which then connects to one or more emergency response agencies.

0042<figref idref="DRAWINGS">FIG. 17</figref> shows security networks in two neighboring residences in which the two security networks cooperate with each other to provide alternate means to reach the PSTN, and in which each security network may provide alternate communications paths for the base units and transponders of the other security network.

0043<figref idref="DRAWINGS">FIG. 18</figref> shows multiple gateways connecting to a telephone line and a gateway and telephone disconnect devices controlling access from telephony devices to the telephone line.

0044<figref idref="DRAWINGS">FIG. 19</figref> shows the multiple communications paths that may exist during the configuration of the security network or a security system.

0045<figref idref="DRAWINGS">FIG. 20</figref> shows multiple gateways connecting to a telephone line and various example base units communicating in a security network.

0046<figref idref="DRAWINGS">FIG. 21</figref> shows a typical statistical relationship between the number of base units in a security network and the probability of any one message being lost (i.e., not received). The exact shape of the curve and values on the axes are dependent upon a specific installation in a specific building.

0047<figref idref="DRAWINGS">FIGS. 22A and 22B</figref> show the locations on the base unit where patch or microstrip antennas may be mounted so as to provide directivity to the transmissions.

0048<figref idref="DRAWINGS">FIG. 23A</figref> shows an example security network where various devices are communicating with each other.

0049<figref idref="DRAWINGS">FIG. 23B</figref> shows an example physical embodiment of a base unit integrated with an outlet.

0050<figref idref="DRAWINGS">FIG. 23C</figref> shows an example security network in which messages between the end point devices can be passed through intermediate devices.

0051<figref idref="DRAWINGS">FIGS. 24A and 24B</figref> show one means by which a base unit may be mounted to a plate, and then mounted to an outlet.

0052<figref idref="DRAWINGS">FIGS. 25A and 25B</figref> show examples of LED generators and LED detectors that may be used as intrusion sensors.

0053<figref idref="DRAWINGS">FIG. 26</figref> shows example physical embodiments of a cigarette lighter adaptor for typical use in a vehicle, a remote sounder, and telephone disconnect devices.

0054<figref idref="DRAWINGS">FIG. 27</figref> shows an architecture for the transponder, sensor, and reader components of an example security network for managing power in the transponder and sensor according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

0055The present invention is a highly reliable system and method for constructing a security network <b>400</b>, or security system, for use in a building, such as a commercial building, single or multifamily residence, or apartment. For consistency with the cross referenced applications, the term security system may be used sometimes, though in the context of this present application, the terms security system and security network <b>400</b> shall be considered interchangeable as they apply to the present invention. The security network <b>400</b> may also be used for buildings that are smaller structures such as sheds, boathouses, other storage facilities, and the like. Throughout this specification, a residential house will be used as an example when describing aspects of the present invention. However, the present invention is equally applicable to other types of buildings. Some forms of the present invention may also provide cordless telephone functionality and may further be packaged in an embodiment familiar to many end users as a cordless telephone system.

0056The security network <b>400</b> described herein is a set of distributed components that together operate to form a system for detecting intrusion and providing other services to a home or building owner. The components are arranged in a two-level architecture, described within this specification as base units <b>200</b> and transponders <b>100</b>. An example security network <b>400</b> can be formed with as few as one base unit <b>200</b> and one transponder <b>100</b>, however the security network <b>400</b> can also grow to include large numbers of both types of devices.

0057Base units <b>200</b> are distinguished by their support for high power RF communications, meaning that these devices are capable of generating continuous and/or frequent wireless transmissions, typically at power levels of 10 or more milliwatts, and typically operating under FCC rules 47 C.F.R. 15.247 or equivalent. Base units <b>200</b> are capable of self-forming a network and communicating with each other over large distances, such as one kilometer or more depending upon exact implementation. Base units <b>200</b> will generally be AC powered and/or have rechargeable batteries, although this is not a requirement.

0058Transponders <b>100</b> are distinguished by their more limited communications capability. Transponders <b>100</b> support low power RF communications and/or backscatter modulation. Low power RF communications means that these devices are only permitted to transmit intermittent wireless communications, typically at average power levels of less than 10 milliwatts, and typically operating under FCC rules 47 C.F.R. 15.231 or 47 C.F.R. 15.249. Transponders <b>100</b> are smaller and less expensive than base units <b>200</b> and do not have access to AC power for either operation or battery recharging. This lack of access to AC power is one reason for limiting the communications capability and transmit power level.

0059A transponder <b>100</b> supporting only backscatter modulation may sometimes be termed a passive transponder <b>150</b>. Passive transponders <b>150</b> cannot independently generate wireless transmissions and can only respond to communications from a base unit <b>200</b> using backscatter modulation. Passive transponders <b>150</b> based only upon backscatter modulation are less expensive, as they do not contain the circuitry to independently generate wireless communications. Passive transponders <b>150</b> are either battery powered or obtain their power from the RF transmissions of base units <b>200</b>. Even with a battery, passive transponders <b>150</b> can have a life of ten or more years as their current drain from the battery is extremely low. Because passive transponders <b>150</b> cannot independently generate wireless transmissions, they are not explicitly governed by any FCC rules and do not require an equipment authorization.

0060A security network <b>400</b> of the present invention may typically include 4 elements: an intrusion sensor <b>600</b>, a transponder <b>100</b>, a base unit <b>200</b>, and a controller function <b>250</b>. <figref idref="DRAWINGS">FIG. 1</figref> shows this example configuration of the security network <b>400</b> with a single base unit <b>200</b> communicating with several transponders <b>100</b>, one of which has an associated intrusion sensor <b>600</b>, one of which has any one of several other sensors <b>620</b>, and a third which has no sensor. The controller function <b>250</b> is logic implemented in firmware or software and runs within one or more base units; it is not shown in the diagram, but in this basic configuration the controller function <b>250</b> is contained within the base unit <b>200</b>.

0061The security network <b>400</b> can be expanded to support multiple base units <b>200</b>. In addition, the security network <b>400</b> can communicate with external networks <b>410</b> using a base unit <b>200</b> containing a telecommunications interface as shown in <figref idref="DRAWINGS">FIG. 23A</figref>. <figref idref="DRAWINGS">FIG. 23C</figref> shows the means by which multiple base units <b>200</b> communicate with each other in the security network <b>400</b> by self-forming a network using high power RF communications. In <figref idref="DRAWINGS">FIG. 23C</figref> some of the base units <b>200</b> can directly communicate with each other and some pairs of base units <b>200</b> can only communicate through one or more intermediate base units. <figref idref="DRAWINGS">FIG. 6</figref> shows an example of how the logical architecture of <figref idref="DRAWINGS">FIG. 23C</figref> might appear in an example residence.

0062The security network <b>400</b> of the present invention differs significantly from existing products in its highly distributed architecture and two-way communications. Instead of being centered around a single control panel, this invention includes a controller function <b>250</b> that can be distributed within and among multiple base units <b>200</b>. Instead of just unidirectional wireless transmitters on windows <b>702</b> and doors <b>701</b>, this invention can support bidirectional wireless communications between a transponder <b>100</b> and base unit <b>200</b>.

0063Base units <b>200</b>, once installed, form a security network <b>400</b> with each other as shown in <figref idref="DRAWINGS">FIGS. 2 and 4</figref>. All of the base units <b>200</b> in the security network <b>400</b> can become aware of and communicate with each other. As used within the present invention, the term base unit <b>200</b> shall apply to a family of devices as shown in <figref idref="DRAWINGS">FIG. 4</figref>. There are two dimensions to consider for base units <b>200</b>: the physical embodiment and the functional components. Base units <b>200</b> can take any one of the following example physical embodiments, among others:

0064Wall Unit <b>262</b>;

0065Tabletop Unit <b>261</b>, such as that used as a cordless telephone base (i.e., fixed part);

0066Ceiling Units such as a smoke/fire/carbon monoxide detector <b>590</b> or a detector collar <b>591</b>;

0067Handheld Unit <b>260</b>, such as that used as a cordless telephone handset (i.e., portable part).

0068Examples of the physical form factors are shown in <figref idref="DRAWINGS">FIGS. 4 and 13</figref>. These example form factors are not intended to be limited and other physical form factors are also possible. A wall unit <b>262</b> will typically plug into and be mounted onto an outlet <b>720</b>. This allows the wall unit <b>262</b> to be placed anywhere within a room, including unobtrusively behind furniture. A tabletop unit <b>261</b> will typically be of a form factor and aesthetic design that allows the unit to sit on a counter or table top and obtain power from a transformer <b>267</b> plugged into a nearby outlet, similar to the base of a cordless telephone system. A ceiling unit will typically be in the form factor of a smoke detector <b>590</b> or smoke detector collar <b>591</b>, and obtain power from the AC power connections to the smoke detector. A handheld unit <b>260</b> will typically be in the form factor of a handheld cordless telephone with a rechargeable battery.

0069As shown in <figref idref="DRAWINGS">FIG. 3</figref>, base units <b>200</b> can include any of the following example functional components:

0070Transceiver for high power RF communications <b>204</b>;

0071Receiver or transceiver for low power RF communications <b>205</b>;

0072Processor <b>203</b>;

0073Memory (volatile and/or non-volatile) <b>211</b>;

0074Power supply (AC, rechargeable or non-rechargeable battery) <b>207</b> and <b>208</b>;

0075Antenna system (antenna and interface circuits) <b>206</b>;

0076Controller function software <b>250</b>;

0077Cordless phone software <b>240</b>;

0078Telecommunications interface <b>220</b> (example types are shown);

0079Other functions <b>221</b> (example types following);

0080Keypad interface <b>265</b>;

0081Display <b>266</b>;

0082Acoustic or audio transducer <b>210</b>;

0083Camera <b>213</b>; and

0084Smoke/fire/CO detector interface <b>212</b>.

0085Every base unit <b>200</b> requires a transceiver for high power RF communications <b>204</b>, a processor <b>203</b>, memory <b>211</b>, at least one form of power supply <b>207</b>, and an antenna system <b>206</b>. Every base unit <b>200</b> is capable of forming a network with other base units <b>200</b>.

0086Any base unit <b>200</b> may further include the controller function <b>250</b> software. Some base units <b>200</b> may not include a controller function <b>250</b>; this may be because that particular base unit <b>200</b> is of a form factor or at a physical location for which it would not be desirable for that base unit <b>200</b> to contain controller function <b>250</b> software. Within any one security network <b>400</b>, and at any one particular time, there will generally be only one base unit <b>200</b> whose controller function has been assigned to be the master controller for that security network <b>400</b>. All other controller functions <b>250</b> within other base units <b>200</b> will generally be slaved to the master controller <b>251</b>. The base unit <b>200</b> whose controller function <b>250</b> is presently the master controller <b>251</b> may sometimes be termed the master controller <b>251</b>.

0087A base unit <b>200</b> that includes a telecom interface <b>220</b> may sometimes be termed a gateway <b>300</b>. The gateway <b>300</b> may use any of several example means for its telecom interface <b>220</b>, including a modem <b>310</b> for connection to a PSTN <b>403</b>, an Ethernet or WiFi or USB interface <b>313</b> for connection to a private or public computer network such as the internet <b>405</b>, or a CDMA or GSM or TDMA <b>311</b> or two-way paging interface <b>312</b> for connection to a radio network such as a CMRS <b>402</b>. For convenience, the term gateway <b>300</b> may be preceded by an identifier describing the type of telecom interface within the gateway <b>300</b>. Therefore, a WiFi gateway <b>520</b> refers to a gateway <b>300</b> containing a WiFi telecom interface <b>313</b>. It is important to note that the term gateway <b>300</b> refers to the functional capability of a base unit <b>200</b> that includes a telecom interface <b>220</b>; the term does not necessarily refer to any particular physical embodiment. For example, both a wall unit <b>262</b> and a tabletop unit <b>261</b> may functionally operate as a gateway <b>300</b>.

0088<figref idref="DRAWINGS">FIG. 5</figref> shows various examples of base units <b>200</b> with various added functional components that can be contained and communicate within a security network <b>400</b>. As can be further seen in <figref idref="DRAWINGS">FIG. 5</figref>, different example gateways <b>300</b> show how the security network <b>400</b> can also communicate to networks and systems external to the security network <b>400</b>.

0089A keypad <b>265</b> may be added to a base unit <b>200</b>, forming a combination base unit with keypad <b>500</b>, to provide one method for user interface. A gateway <b>300</b> can be provided to enable communications between the security network <b>400</b> and external networks <b>410</b> such as, for example, a security monitoring company <b>460</b>. The gateway <b>300</b> may also convert protocols between the security network <b>400</b> and a WiFi network <b>404</b> or a USB port of a computer <b>450</b>. A siren driver <b>551</b> may be added to a base unit <b>200</b> to provide loud noise-making capability. An email terminal <b>530</b> can be added to a base unit <b>200</b> to initiate and receive messages to/from external networks <b>410</b> and via a gateway <b>300</b>. Other sensors <b>620</b> may be added to detect fire, smoke, heat, water, temperature, vibration, motion, as well as other measurable events or items. A camera and/or audio terminal <b>540</b> may be added to a base unit <b>200</b> to enable remote monitoring via a gateway <b>300</b>. A keyfob <b>561</b> may be added to enable wireless function control of the security network <b>400</b>. This list of devices that can be added is not intended to be exhaustive, and other types can also be created and added as well.

0090The distributed nature of the security network <b>400</b> is shown in the example layout in <figref idref="DRAWINGS">FIG. 6</figref> for a small house. At each opening in the house, such as windows <b>702</b> and doors <b>701</b>, for which monitoring is desired, an intrusion sensor <b>600</b> and transponder <b>100</b> are mounted. While identified separately, the intrusion sensor <b>600</b> and transponder <b>100</b> may be physically integrated into the same physical package. In a pattern determined by the layout of the house or building into which the security network <b>400</b> is to be installed, one or more base units <b>200</b> are mounted. Each base unit <b>200</b> is in wireless communications with one or more transponders <b>100</b>. Each base unit <b>200</b> is also in communications with one or more other base units <b>200</b>, each of which may contain a controller function <b>250</b>. In general, each base unit <b>200</b> is responsible for the transponders <b>100</b> in a predetermined communications range of each base unit <b>200</b>. As is well understood to those skilled in the art, the range of wireless communications is dependent, in part, upon many environmental factors in addition to the specific design parameters of the base units <b>200</b> and transponders <b>100</b>.

0091According to U.S. Census Bureau statistics, the median size of one-family houses has ranged from 1,900 to 2,100 square feet (176 to 195 square meters) in the last ten years, with approximately two-thirds under 2,400 square feet (223 square meters). This implies typical rooms in the house of 13 to 20 square meters, with typical wall lengths in each room ranging from 3 to 6 meters. It is likely in many residential homes that most installed base units <b>200</b> will be able to communicate with transponders <b>100</b> in multiple rooms. Therefore, in many cases with this system it will be possible to install fewer base units <b>200</b> than major rooms in a building, creating a security network <b>400</b> with excellent spatial antenna diversity as well as redundancy in the event of single component failure.

0092Base units <b>200</b> will typically communicate with other base units <b>200</b> as well as passive transponders <b>150</b> using frequencies in one or more of the following unlicensed frequency bands: 902 to 928 MHz, 2435 to 2465 MHz, 2400 to 2483 MHz, or 5725 to 5850 MHz. These bands permit the use of unlicensed secondary transmitters, and are part of the bands that have become popular for the development of cordless phones and wireless LAN networks, thereby leading to the wide availability of many low cost components. Three of the FCC rule sets applicable to the present invention will be discussed briefly.

0093Transmissions regulated by FCC rules 47 C.F.R. 15.245 permit field disturbance sensors with field strengths of up to 500 mV/m at 3 meters (measured using an average detector function; the peak emission limit may be up to 20 dB higher). This implies an averaged transmission power of 75 mW and a peak transmission power of up to 7.5 Watts. Furthermore, transmissions under these rules do not suffer the same duty cycle constraints as existing wireless security system transmitters operating under 47 C.F.R. 15.231 (a). This rule section would only apply when a base unit <b>200</b> is communicating with a passive transponder <b>150</b> using backscatter modulation, which qualifies the base unit <b>200</b> as a field disturbance sensor. Prior art wireless security system transmitters are not field disturbance sensors.

0094Transmissions regulated by FCC rules 47 C.F.R. 15.247 permit frequency hopping (FHSS) or digital modulation (DM) systems at transmission powers up to 1 Watt into a 6 dBi antenna, which results in a permitted 4 Watt directional transmission. In order for a FHSS device to take advantage of the full permitted power, the FHSS device must frequency hop at least once every 400 milliseconds.

0095Transmissions regulated by FCC rules 47 C.F.R. 15.249 permit field strengths of up to 50 mV/m at 3 meters (measured using an average detector function; the peak emission limit may be up to 20 dB higher). This implies an averaged transmission power of 750 μW and a peak transmission power of up to 75 mW. Unlike 47 C.F.R. 15.247, rule section 47 C.F.R. 15.249 does not specify modulation type or frequency hopping.

0096Most other products using these unlicensed bands are other transient transmitters operating under 47 C.F.R. 15.247 and 47 C.F.R. 15.249, and so even though it may seem that many products are available and in use in these bands, in reality there remains a lot of available space in the band at any one instant in time, especially in residential homes. Most transmitters operating under 47 C.F.R. 15.247 are frequency hopping systems whereby the given spectrum is divided into channels of a specified bandwidth, and each transmitter can occupy a given channel for only 400 milliseconds. Therefore, even if interference occurs, the time period of the interference is brief. In most cases, the base units <b>200</b> can operate without incurring interference or certainly without significant interference. In residential homes, the most common products using these bands are cordless telephones, for which there are no standards (other than the 47 C.F.R. 15.247 requirements). Each phone manufacturer uses its own modulation and protocol format. For data devices, there are several well-known standards that use the 2400 to 2483 MHz band, such as 802.11, 802.11b (WiFi), Bluetooth, ZigBee (HomeRF-lite), and IEEE 802.15.4, among others.

0097The present invention has a substantial advantage for the aforementioned products in that many of the physical embodiments of the base units <b>200</b> are fixed. Other products such as cordless phones and various data devices usually have at least one handheld, usually battery powered, component. The FCC's Maximum Permitted Exposure (MPE) guidelines, described in OET <b>65</b>, generally cause manufacturers to limit transmission power of handheld devices to 100 mW or less. Since most wireless links are symmetrical, once the handheld device (such as the cordless phone) is power limited, any fixed unit (such as the cordless base unit) is also limited in power to match the handheld device. Given that many of the physical embodiments of the base units <b>200</b> of the security network <b>400</b> are not handheld, they can use the full power permitted by the FCC rules and still meet the MPE guidelines.

0098As discussed earlier, the preferred means of communications by and between base units <b>200</b> is high power RF communications. The invention is not limiting, and modulation formats and protocols using either FHSS or DM can be employed. As one example, the high power RF communications can use Gaussian Frequency Shift Keyed (GFSK) modulation with FHSS. This particular modulation format has already been used quite successfully and inexpensively for Bluetooth, 802.11, and other data systems to achieve raw data rates on the order of 1 Mbps. In order to take maximum advantage of the permitted power limits in, for example, the 2400 to 2483 MHz band, if a FHSS protocol is chosen, GFSK or otherwise, at least 75 hopping channels should be used and if a DM protocol is chosen, a minimum 6 dB bandwidth of 500 KHz should be used. Any designer of a security network <b>400</b> under this invention can take advantage of the fixed nature of the base units <b>200</b> as well as the relatively low information rate requirements to select a modulation format and protocol with high link margins.

0099One approach that a designer may consider is a multi-rate design wherein the high power RF communications uses different data rates for different types of data. For example, the day to day management of the security network <b>400</b> may involve a low volume of commands and messages. The link margins can be improved by implementing a lower data rate. Certain base units, such as those including a camera <b>213</b>, may have high rate requirements that are only required when actually transferring a picture. Therefore, it is possible to design a protocol where the link runs at a higher rate for certain transfers (i.e., pictures) and a lower rate for normal communications. It should be noted that most other products in these bands have at least one mobile component and high data rates are required. Therefore, in spite of the presence of other products, the high power RF communications used in the security network <b>400</b> should achieve higher reliability and range, and lower susceptibility to interference than other collocated products.

0100When using high power RF communications, the base units <b>200</b> function as a network of nodes. A message originating on one base unit <b>200</b> may pass through intermediate base units <b>200</b> before terminating on the destination base unit, as shown in <figref idref="DRAWINGS">FIGS. 23C and 10</figref>. The base units <b>200</b> determine their own network topology based upon the ability of each base unit <b>200</b> to reliably transmit and/or receive the transmissions to/from other base units. As discussed herein, the antennas <b>206</b> used in these base units <b>200</b> may be directional, and therefore it is not always certain that each base unit <b>200</b> can directly transmit to and receive from every other base unit <b>200</b>. However, given the power limits and expected distribution of devices in typical homes and buildings, it can be generally expected that each base unit <b>200</b> can communicate with at least one other base unit, and that the base units <b>200</b> can then form for themselves a network that enables the routing of a message from any one base unit <b>200</b> to any other base unit <b>200</b>. Networking protocols are well understood in the art and therefore not covered here. The base units <b>200</b> described herein typically may use a unique (at least within the home and neighbor security networks <b>400</b>) originating and destination address of each base unit <b>200</b> in the header of each message sent in routing messages within the security network <b>400</b>.

0101While the base units <b>200</b> use 47 C.F.R. 15.247 rules for their high power RF communications with each other, the base units <b>200</b> can use both 47 C.F.R. 15.245 and 47 C.F.R. 15.247 rules for their wireless communications with passive transponders <b>150</b>. Thus, the base units <b>200</b> can communicate to the transponders using one protocol, at a maximum power of 4 W for any length of time, and then switch to a second protocol, if desired, at a maximum power of 7.5 W to obtain a response from a passive transponder <b>150</b>. While the base unit <b>200</b> can transmit at 7.5 W for only 1 ms under 47 C.F.R. 15.245, that time period is more than enough to obtain tens or hundreds of bits of data from a transponder <b>100</b>. The extra permitted 2.7 dB of power under 47 C.F.R. 15.245 is useful for increasing the range of the base unit <b>200</b>. In a related function, the base unit <b>200</b> can use the longer transmission times at 4 W to deliver power to the transponders <b>100</b>, as described elsewhere, and reserve the brief bursts at 7.5 W only for data transfer.

0102Each base unit <b>200</b> typically receives communications from one or more passive transponders <b>150</b> using modulated backscatter techniques. To use modulated backscatter, a base unit <b>200</b> transmits a wireless signal to a passive transponder <b>150</b>. The passive transponder <b>150</b> modulates the impedance of its antenna, thereby altering reflections of the wireless signal off its antenna. The base unit <b>200</b> then detects the changes in reflected signal. The impedance changes are made using a predetermined rate whose frequency can be measured by the base unit <b>200</b> to distinguish data bits.

0103These techniques are very well understood by those skilled in the art, and have been well discussed in a plethora of literature including patent specifications, trade publications, marketing materials, and the like. For example, the reader is directed to RFID Handbook; Radio-Frequency Identification: Fundamentals And Applications, by Klaus Finkenzeller, published by John Wiley, 1999. U.S. Pat. No. 6,147,605, issued to Vega et al., provides additional material on the design and theory of modulated backscatter techniques. U.S. Pat. No. 6,549,064, issued to Shanks et al., also provides material on the design and theory of modulated backscatter techniques. Therefore, this same material is not covered here. Presently, a number of companies produce miniaturized chipsets, components, and antennas for base units <b>200</b> and transponders. Many of these chipsets, though designed for the 13.56 MHz band, are applicable and/or will be available in the higher bands such as those discussed here. For example, Hitachi has recently announced the manufacture of its mu-chip, which is a 2.4 GHz transponder <b>100</b> measuring only 0.4 mm square. The most important point here is that the wide availability of parts permits the designer many options in choosing the specific design parameters of the base unit <b>200</b> and passive transponder <b>150</b> and therefore the innovative nature of this invention is not limited to any specific circuit design implementing the wireless link between the base unit <b>200</b> and passive transponder <b>150</b>.

0104The extensive literature on backscatter modulation techniques and the wide availability of parts does not detract from the innovative application and combination of these techniques and parts to the present invention. Most applications of backscatter modulation have been applied to mobile people, animals, or things that must be authorized, tracked, counted, or billed. No one has previously considered the novel application of low cost backscatter modulation components to solve the problem of monitoring fixed assets such as the windows <b>702</b> and doors <b>701</b> that comprise the openings of buildings or other sensors <b>600</b> and <b>620</b>. All present transmitters constructed for prior art wireless security systems are more expensive than the backscatter modulation-based design of the present invention because of the additional components required for active transmission. Furthermore, no one has considered the use of multiple, distributed low cost base units <b>200</b> with overlapping coverage so that a building's security is not dependent on a single, vulnerable, and historically unreliable central transceiver.

0105There are several examples of the advantages that the present backscatter modulation approach offers versus prior art wireless security systems. Prior art wireless security systems limit status reporting by transmitters to times even longer than the FCC restriction of once per hour in order to conserve the battery in the transmitter. The backscatter modulation approach herein does not have the same battery limitation because of the modulated backscatter design. Prior art wireless security systems are subject to both false positive and false negative indications because centrally located transceivers have difficulty distinguishing noise from real signals. The central transceiver has little control over the time of transmission by a transmitter and therefore must evaluate every signal, whether noise, interference, or real transmission. This is made more difficult because the prior art central transceivers are not always located centrally in the house. Professional installers generally hide these central transceivers in a closet or similar enclosure to prevent an intruder from easily spotting the central transceiver and disabling it. Each wall or door through which signals must pass to reach a central transceiver can typically cause a loss of up to 10 dB in signal power. In contrast, the backscatter modulation approach places all of the transmission control in the master controller <b>251</b> and base unit <b>200</b>. The base unit <b>200</b> only looks for a return response during a read. Therefore the base unit <b>200</b> can be simpler in design.

0106Some centralized transceivers attempt to use diversity antennas to improve their reliability; however, these antennas are separated only by the width of the packaging, which is frequently much less than one wavelength of the chosen frequency (i.e., 87 cm at 345 MHz and 69 cm at 433 MHz). As is well known to those skilled in the art of wireless, spatial diversity of antennas works best when the antennas are separated by more than one wavelength at the chosen frequency. With the present invention, base units <b>200</b> are separated into multiple rooms, creating excellent spatial diversity and the ability to overcome environmental effects such as multipath and signal blockage. Multipath and signal blockage are effects of the RF path between any transmitter and receiver. Most cellular systems use diversity antennas separated by multiple wavelengths to help overcome the effects of multipath and signal blockage. Under the present invention, in most installations there will be multiple base units <b>200</b> in a building. There will therefore be an independent RF path between each base unit <b>200</b> and each transponder <b>100</b>. The master controller <b>251</b> may sequence transmissions from the base units <b>200</b> so that only one base unit <b>200</b> is transmitting at a time. Besides reducing the potential for interference, this allows the other base units <b>200</b> to listen to both the transmitting base unit <b>200</b> and the subsequent response from the transponders. If the RF path between the transmitting base unit <b>200</b> and the transponder <b>100</b> is subject to some form of multipath or signal blockage, it is possible and even highly probable that one of the remaining base units <b>200</b> is capable of detecting and interpreting the signal. If the transmitting base unit <b>200</b> is having trouble receiving an adequate response from a particular transponder <b>100</b>, the master controller <b>251</b> may then poll the remaining base units <b>200</b> to determine whether the response was received by any of them.

0107One major design advantage of the present invention versus all other applications of backscatter modulation is the fixed and static relationship between each base unit <b>200</b> and the transponders. While RFID readers for other applications must include the complexity to deal with many simultaneous tags in the read zone, tags moving rapidly, or tags only briefly in the read zone, the present invention can take advantage of controlled static relationship in the following ways.

0108While there may be multiple transponders <b>100</b> in the read zone of each base unit, the base unit <b>200</b> can poll each transponder <b>100</b> individually, preventing collisions or interference. In addition, because each transponder <b>100</b> is responding individually, the base unit <b>200</b> can use the expected response bit sequence to improve the receive processing gain. A specific transponder <b>100</b> is responding at a specific time, and at least a portion of the response will contain bits in a predetermined sequence.

0109Because the transponders <b>100</b> are fixed, the base unit <b>200</b> can use longer integration times in its signal processing to increase the reliability of the read signal, permitting successful reading at longer distances and lower power when compared with backscatter modulation applications with mobile tags.

0110Furthermore, the base unit <b>200</b> can make changes in specific frequency while remaining within the specified unlicensed frequency band, in an attempt to find, for each transponder <b>100</b>, an optimal center frequency, given the manufacturing tolerances of the components in each transponder <b>100</b> and any environment effects that may be creating more absorption or reflection at a particular frequency. In a similar manner, the base unit <b>200</b> can learn the center frequencies of the marking and spacing bits modulated by each transponder <b>100</b>. While these center frequencies may be nominally known and designed into the transponder <b>100</b>, there is likely a significant probability that the manufacturing process will result in a variation of actual modulation frequencies. By matching its demodulation process to each transponder <b>100</b>, the base unit <b>200</b> can improve its signal processing margin.

0111Because the multiple base units <b>200</b> are controlled from a single master controller <b>251</b>, the controller function <b>250</b> can sequence the base units <b>200</b> in time so that the base units <b>200</b> do not interfere with each other.

0112Because there will typically be multiple base units <b>200</b> installed in each home, apartment, or other building, the controller function <b>250</b> can use the excellent spatial diversity created by the distributed nature of the base units <b>200</b> to increase and improve the reliability of each reading operation. That is, one base unit <b>200</b> can initiate the transmission sequence, but multiple base units <b>200</b> can tune and read the response from the transponder <b>100</b>. Thus the multiple base units <b>200</b> can operate as a network of receivers to demodulate and interpret the response from the transponder <b>100</b>.

0113Because the transponders <b>100</b> are typically static, and because the events (such as intrusion) that affect the status of the sensors connected to transponders <b>100</b> are relatively slow compared to the speed of electronics in the base units, the base units <b>200</b> have the opportunity to pick and choose moments of low quiescent interference from other products in which to perform their reading operations with maximum signal to noise ratio potential—all without missing the events themselves.

0114Because the path lengths and path loss from each transponder <b>100</b> to the base unit <b>200</b> are relatively static, the base unit <b>200</b> can use different power levels when communicating with each transponder <b>100</b>. Lower path losses require lower power to communicate; conversely the base unit <b>200</b> can step up the power, within the specified limits of the FCC rules, to compensate for higher path losses. The base unit <b>200</b> can determine the lowest power level to use for each transponder <b>100</b> by sequentially stepping down its transmit power on successive reading operations until no return signal can be detected. Then the power level can be increased one or two incremental levels. This determined level can then be used for successive reading operations. This use of the lowest necessary power level for each transponder <b>100</b> can help reduce the possibility of interference while ensuring that each transponder <b>100</b> can always be read.

0115Finally, for the same static relationship reasons, the master controller <b>251</b> and base units <b>200</b> can determine and store the typical characteristics of transmission between each transponder <b>100</b> and each base unit <b>200</b> (such as signal power, signal to noise ratio, turn on time, modulation bit time, etc.), and determine from any change in the characteristics of transmission whether a potential problem exists. Thus, the base unit <b>200</b> can immediately detect attempts to tamper with the transponder <b>100</b>, such as partial or full shielding, deformation, destruction, or removal.

0116By taking advantage of the foregoing techniques, the base unit <b>200</b> of the present invention can support a wireless range of up to 30 meters when communicating with passive transponders <b>150</b>, depending upon the building construction materials, placement of each base unit <b>200</b> in a room, and the furniture and other materials in the room which may have certain reflective or absorptive properties. This range is more than sufficient for the majority of homes and other buildings in the target market of the present security network <b>400</b>.

0117Base units <b>200</b> may include receivers or transceivers <b>205</b> in order to communicate with transponders <b>100</b> using low power RF communications. Transponders <b>100</b> using low power RF communications will typically transmit using the 300 to 500 MHz band and will typically be operating under FCC rule 47 C.F.R. 15.231. In particular, frequencies at or near 315, 319, 345, and 434 MHz have been historically favored for low power RF transmitters and many components are available for constructing transponders <b>100</b> that operate at these frequencies. As discussed earlier, prior art wireless security systems suffer from limitations caused by the low power and intermittent nature of the transmissions from transponders operating under this rule section, coupled with the central receiver architecture of these prior art systems.

0118The present invention has a number of design advantages over prior art wireless security systems, even when using transponders <b>100</b> operating under the limitations of FCC rule 47 C.F.R. 15.231. The following advantages apply for a security network <b>400</b> wherein the base units <b>200</b> include receivers or transceivers in order to communicate with transponders <b>100</b> using low power RF communications.

0119The security network <b>400</b> permits the installation of multiple base units <b>200</b>. These base units <b>200</b> can be installed in various rooms of a building, in a neighboring building, or in a nearby outbuilding. The base units <b>200</b> in the security network <b>400</b> form a spatially diverse network of receivers or transceivers. This spatial diversity provides a significant increase in reliability when compared with the limited antenna diversity of prior art wireless security systems. <figref idref="DRAWINGS">FIG. 21</figref> shows an example curve relating the number of base units <b>200</b> (in the present invention base units <b>200</b> contain the receivers receiving communications from transponders <b>100</b>; in prior art systems other terms may be used for the wireless receivers) to the probability of message loss in the security network <b>400</b>. It can be seen that increasing the number of receivers, especially in a spatially diverse manner, dramatically decreases the probability of message loss. Prior art systems will generally experience losses in the vicinity of point A in <figref idref="DRAWINGS">FIG. 21</figref>, while the security network <b>400</b> can easily operate in the vicinity of point B.

0120The RF propagation path from each transponder <b>100</b> to each base unit <b>200</b> is statistically independent, therefore even if signal blockage, interference, or multipath is affecting one RF propagation path, there will be a statistically high probability that the other RF propagation paths will not be simultaneously experiencing the same problem. Furthermore, there will be a different path length from each transponder <b>100</b> to each base unit, increasing the likelihood that at least one base unit <b>200</b> can receive a message transmitted by a transponder <b>100</b> with sufficient signal to noise. Each base unit <b>200</b> will attempt to receive and demodulate the intended transponder <b>100</b> message, creating a base unit-specific version of the message. Furthermore, each base unit <b>200</b> may determine certain quality factors associated with its version of the message. These quality factors may be based upon received signal strength, received signal to noise or signal to interference ratios, received errors or error detection/recovery codes, or other similar factors. The versions may differ somewhat based upon the problems that may have been experienced on each RF propagation path from the transponder <b>100</b> to each base unit <b>200</b>. Each base unit <b>200</b> may use high power RF communications to send its base unit-specific version of the message that it received from a transponder <b>100</b> to a controller function <b>250</b>, and the controller function <b>250</b> may compare portions of the different base unit-specific versions of the transponder <b>100</b> message in order to determine the most likely correct version of the intended transponder <b>100</b> message. If necessary, the controller function <b>250</b> can combine portions of multiple base unit-specific versions of the message together in order to form or reconstruct the intended transponder <b>100</b> message.

0121Base units <b>200</b> belonging to different security networks <b>400</b> may be within wireless communications range of each other. For example, two neighboring homes or buildings may each have a security network <b>400</b> installed. A base unit <b>200</b> in a first security network <b>400</b> in a first residence <b>740</b> in <figref idref="DRAWINGS">FIG. 17</figref> may receive low power RF communications from a transponder <b>100</b> in a second security network <b>400</b> in a second residence <b>741</b> in <figref idref="DRAWINGS">FIG. 17</figref>. The base unit <b>200</b> in the first security network <b>400</b> may be configured to use high power RF communications to send its version of the message that the first base unit <b>200</b> received from the transponder <b>100</b> in the second security network <b>400</b> to a controller function <b>250</b> in a base unit <b>200</b> in the second security network <b>400</b>. Thus nearby security networks <b>400</b> may cooperate with each other in receiving low power RF communications from transponders <b>100</b>.

0122Since base units <b>200</b> include processors <b>203</b> and memory <b>211</b>, the base units <b>200</b> may also include receivers that incorporate signal processing gain to improve the reception of low power RF communications from transponders <b>100</b>. Prior art wireless security systems use receivers that attempt to demodulate low power RF communications on a symbol by symbol basis. That is, the receivers in prior art wireless security systems demodulate each symbol independently of each other symbol in the message. Certain symbols may be demodulated correctly while other symbols may not be demodulated correctly. The base units <b>200</b> of the present invention may use signal processing techniques whereby the base unit <b>200</b> may receive multiple symbols within the message transmitted by the transponder <b>100</b> and then compare the multiple symbols against an expected set of symbols. This process of comparison is sometimes known in the art as integration or correlation, and the result is an improvement in message demodulation due to signal processing gain. The integration may be coherent or incoherent. For an example message length of 64 bits, coherent integration can result in a signal processing gain of 10 log 64, or 18 dB. This means that a base unit <b>200</b> can have a receive sensitivity that is as much as 18 dB better than the receiver in a prior art wireless security system.

0123Every base unit <b>200</b> will typically support both high power RF communications with other base units <b>200</b> and communications with transponders <b>100</b>. Some base units <b>200</b> may support additional functions as discussed elsewhere. <figref idref="DRAWINGS">FIG. 3</figref> shows a block diagram of an example embodiment of the base unit <b>200</b>. Typically, the base unit <b>200</b> includes a microprocessor <b>203</b>, memory <b>211</b>, unit specific software, RF modulation and receiving circuits <b>204</b>, an antenna <b>206</b>, and power supply <b>207</b>. The microprocessor <b>203</b> and RF modulation and receiving circuits <b>204</b> may be incorporated as a single chipset or discretely separated.

0124One manner in which to build a low cost base unit <b>200</b> is to use an integrated cordless phone chipset combined with a limited number of additional components. However, other base units <b>200</b> can also be built using discrete mixers, filters, amplifiers, etc. that are not integrated into a single chipset. While <figref idref="DRAWINGS">FIG. 3</figref> shows only a single antenna <b>206</b> for simplicity, it may be advantageous for the base unit <b>200</b> to contain more than one antenna to provide increased diversity, directivity, or selectivity. When more than one antenna is present, the RF modulation and/or receiving circuits <b>204</b> may enable the switching between the multiple antenna elements <b>206</b>. Alternately, the design may include separate RF modulation and/or receiving circuits <b>204</b> for each antenna element. This may help provide greater separation for the transmit and receive signals. If the base unit <b>200</b> is to also include a controller function <b>250</b>, the microprocessor <b>203</b> will also require sufficient memory <b>211</b> for program and data storage.

0125Base units <b>200</b> can be implemented for use with transponders <b>100</b> that employ low power RF communications or passive transponders <b>150</b> that employ backscatter modulation. Within a single security network <b>400</b>, typically all transponders <b>100</b> would commonly use only one communications type or the other. Therefore, the RF modulation and receiving circuits <b>204</b> of the base unit <b>200</b> should typically reflect the selected communications type for the transponders <b>100</b> in the particular security network <b>400</b>. If the transponders <b>100</b> in the security network <b>400</b> employ low power RF communications, then the RF modulation and/or receiving circuits must support both high power RF communications and low power RF communications. If the transponders in the security network <b>400</b> employ backscatter modulation (i.e., they are passive transponders <b>150</b>), then the RF modulation and/or receiving circuits will typically be required to only support high power RF communications.

0126If battery backup is desired, the packaging of the base unit <b>200</b> also permits the installation of a battery <b>208</b> for backup purposes in case normal power supply <b>207</b> is interrupted. It is also possible to construct an embodiment without a local power supply <b>207</b> and that runs entirely from a battery <b>208</b>. One such embodiment may take a physical form similar to a cordless phone handheld unit <b>260</b>.

0127The inventive base unit <b>200</b> need not be limited to any particular modulation scheme for either its high power RF communications or support for backscatter modulation by a passive transponder <b>150</b>. The choice of the microprocessor <b>203</b>, RF modulation and/or receiving circuits <b>204</b>, and antenna <b>206</b> may be influenced by various modulation considerations. For example, because the base unit <b>200</b> and transponder <b>100</b> may operate in one of the shared frequency bands allocated by the FCC, these devices, as do all Part <b>15</b> devices, are required to accept interference from other Part <b>15</b> devices. It is primarily the responsibility of the base unit <b>200</b> to manage communications with the transponder <b>100</b>, and therefore the following are some of the capabilities that may be included in the base unit <b>200</b> to mitigate interference.

0128Passive transponders <b>150</b> use backscatter modulation, which alternately reflects or absorbs the signal radiated by the base unit <b>200</b> in order to send its own data back. Therefore, a passive transponder <b>150</b> will automatically follow, by design, the specific frequency and modulation used by the base unit <b>200</b>. This is a significant advantage versus prior art wireless security system transmitters, which can only transmit at a single modulation scheme with the carrier centered at a single frequency. If interference is encountered at or near that single frequency, these transmitters of prior art wireless security systems have no ability to alter their transmission characteristics to avoid or mitigate the interference.

0129A base unit <b>200</b> can be implemented to support any of the following modulation schemes, though the present invention is not limited to just these modulation schemes. As is well known in the art, there are many modulation techniques and variations within any one modulation technique, and designers have great flexibility in making choices in this area. The simplest is a carrier wave (CW) signal, at a variety of frequency choices within the allowable bandwidth. A CW conveys no information from the base unit <b>200</b> to a passive transponder <b>150</b>, but allows a passive transponder <b>150</b> to modulate the return signal as described herein. The base unit <b>200</b> would typically use another modulation scheme such as Binary Phase Shift Keyed (BPSK), Gaussian Minimum Shift Keyed (GMSK), Gaussian Frequency Shift Keyed (GFSK) or even on-off keyed (OOK) AM, when sending data to a transponder <b>100</b>, but can use CW when expecting a return signal. The base unit <b>200</b> can concentrate its transmitted power into this CW, permitting this narrowband signal to overpower a portion of the spread spectrum signal typically used by other devices operating in the unlicensed bands. If the base unit <b>200</b> is unsuccessful with CW at a particular frequency, the base unit <b>200</b> can shift frequency within the permitted band. As stated, under the present invention a passive transponder <b>150</b> will automatically follow the shift in frequency by design. Rather than repeatedly generating CW at a single frequency, the base unit <b>200</b> can also frequency hop according to any prescribed pattern. The pattern may be predetermined or pseudorandom. This pattern can be adaptive and can be varied, as needed to avoid interference.

0130There may be times when the interference experienced by the base unit <b>200</b> is not unintentional and not coming from another Part <b>15</b> device. One means by which a very technically knowledgeable intruder may attempt to defeat the security network <b>400</b>, or any wireless system, of the present invention is by intentional jamming. Jamming is an operation by which a malicious intruder independently generates a set of radio transmissions intended to overpower or confuse legitimate transmissions. In this case, the intruder would likely be trying to prevent one or more transponders from reporting a detected intrusion to the base unit, and then to the master controller <b>251</b>. Jamming is, of course, illegal under the FCC rules; however intrusion itself is also illegal. In all likelihood, a person about to perpetrate a crime may not give any consideration to the FCC rules. Therefore, the base unit <b>200</b> may also contain algorithms that can determine within a reasonable probability that the base unit <b>200</b> is being subjected to jamming. For example, if one or more base units <b>200</b> detect a change in the radio environment, in a relatively short predetermined period of time, wherein attempted changes in modulation schemes, power levels, and other parameters are unable to overcome the interference, the master controller <b>251</b> can cause an alert indicating that it is out of communications with one or more transponders with the likely cause being jamming. This condition can be distinguished from the failure of a single transponder <b>100</b> by a simultaneous and parallel occurrence of the change in RF environment, caused by signals not following known FCC transmission rules for power, duty cycle, bandwidth, modulation, or other related parameters and characteristics. The alert can allow the building owner or emergency response agency <b>460</b> to decide upon an appropriate response to the probable jamming.

0131Many homeowners desire monitoring of their security networks <b>400</b> by an alarm services company <b>460</b>. The inventive security network <b>400</b> permits monitoring as well as access to various external networks <b>410</b> through a family of devices known as gateways <b>300</b>, each of which permits access from the security network <b>400</b> to external devices and networks using different protocols and physical connection means. A gateway <b>300</b> is a base unit <b>200</b> with an added telecommunications interface. Each gateway <b>300</b> is configured with appropriate hardware and software that match the external network <b>410</b> to which access is desired. As shown in <figref idref="DRAWINGS">FIGS. 16 and 7</figref>, examples of external networks <b>410</b> to which access can be provided are private Ethernets <b>401</b>, CMRS <b>402</b>, PSTN <b>403</b>, WiFi <b>404</b>, and the Internet <b>405</b>. This list of external networks <b>410</b> is not meant to be limiting, and appropriate hardware and software can be provided to enable the gateway <b>300</b> to access other network formats and protocols as well. Private Ethernets <b>401</b> are those which might exist only within a building or residence, servicing local computer terminals <b>450</b>. If the gateway <b>300</b> is connected to a private Ethernet <b>401</b>, access to the Internet <b>405</b> can then be provided through a cable modem <b>440</b>, DSL <b>441</b>, or other type of broadband network <b>442</b>. There are too many suppliers to enumerate here.

0132A block diagram of the gateway <b>300</b> is the same as that of the base unit shown in <figref idref="DRAWINGS">FIG. 3</figref>. Typically, the gateway <b>300</b> includes a microprocessor <b>203</b>, memory <b>211</b>, unit specific software, RF modulation and receiving circuits <b>204</b>, an antenna <b>206</b>, and power supply <b>207</b>. The microprocessor <b>203</b> and RF modulation and receiving circuits <b>204</b> may be incorporated as a single chipset or discretely separated. The telecommunications interface <b>220</b> will vary depending upon the external network to which the gateway <b>300</b> is to connect. The gateway <b>300</b> will typically communicate with the base units <b>200</b> using high power RF communications.

0133As shown in <figref idref="DRAWINGS">FIGS. 16 and 20</figref>, the security network <b>400</b> permits the installation of multiple gateways <b>300</b> in a single security network <b>400</b>, each of which can interface to the same or different external networks <b>410</b>. For example, a second gateway <b>300</b> can serve to function as an alternate or backup gateway <b>300</b> for cases in which the first gateway <b>300</b> fails, such as component failure, disablement or destruction by an intruder, or loss of power at the outlet where the first gateway <b>300</b> is plugged in. If there are multiple gateways installed in a security network <b>400</b>, these gateways may be located in different buildings and be connected to different networks. For example, a user may install a security network <b>400</b> including a gateway <b>300</b> in their residence <b>740</b> and then also place a second gateway <b>300</b> in their neighbor's residence <b>741</b>. The first gateway <b>300</b> is then connected to one telephone line and the second gateway <b>300</b> is then connected to the neighbor's telephone line (<figref idref="DRAWINGS">FIG. 17</figref>).

0134Homeowners and building owners generally desire one or two types of alerts in the event that an intrusion is detected. First, an audible alert may be desired whereby a loud siren <b>551</b> is activated both to frighten the intruder and to call attention to the building so that any passers-by may take notice of the intruder or any evidence of the intrusion. However, there are also scenarios in which the building owner prefers the so called silent alert whereby no audible alert is made so as to lull the intruder into believing he has not been discovered and therefore may still be there when law enforcement personnel arrive. The second type of alert involves messaging an emergency response agency <b>460</b>, indicating the detection of an intrusion and the identity of the building, as shown in <figref idref="DRAWINGS">FIGS. 8 and 16</figref>. The emergency response agency <b>460</b> may be public or private, depending upon the local customs, and so, for example, may be an alarm services company <b>460</b> or the city police department <b>460</b>.

0135The gateway <b>300</b> of the inventive system supports the second type of foregoing alert by preferably including different telecommunications interfaces <b>220</b>, or modules, such as for example a modem module <b>310</b>, wireless module <b>311</b> and <b>312</b>, WiFi module <b>313</b>, or Ethernet module <b>313</b>. The modem module <b>310</b> is used for connection to a public switched telephone network (PSTN) <b>403</b>; the wireless module <b>311</b> is used for connection to a commercial mobile radio service (CMRS) network <b>402</b> such as any of the widely available CDMA, TDMA, or GSM-based 2G, 2.5G, or 3G wireless networks. The WiFi module <b>313</b> is used for connection to private or public WiFi networks <b>404</b>; the Ethernet module <b>313</b> is use for connection to private or public Ethernets <b>401</b>.

0136Certain building owners will prefer the high security level offered by sending an alert message through a CMRS network <b>402</b> or WiFi network <b>404</b>. The use of a CMRS network <b>402</b> or WiFi network <b>404</b> by the gateway <b>300</b> overcomes a potential point of failure that occurs if the intruder were to cut the telephone wires <b>431</b> prior to attempting an intrusion. If the building owner has installed at least two gateways <b>300</b> in the system, one gateway <b>300</b> may have a wireless module <b>311</b>/<b>312</b> installed and a second may have a modem module <b>310</b> installed. This provides the inventive security network <b>400</b> with two separate communication paths for sending alerts to the emergency response agency <b>460</b> as shown in <figref idref="DRAWINGS">FIG. 8</figref>. By placing different gateways <b>300</b> (<figref idref="DRAWINGS">FIGS. 16 and 20</figref>) in very different locations in the building, the building owner significantly decreases the likelihood that an intruder can discover and defeat the security network <b>400</b>.

0137Any base unit <b>200</b>, including gateways <b>300</b>, may include a controller function <b>250</b>. Prior art alarm panels typically contain a single controller, and all other contacts, motion detectors, etc. are fairly dumb from an electronics and software perspective. For this reason, the alarm panel must be hidden in the house because if the alarm panel were discovered and disabled, all of the intelligence of the system would be lost. The controller function <b>250</b> of the present invention may be distributed through many or all of the base units <b>200</b> in the security network <b>400</b> and shown in <figref idref="DRAWINGS">FIG. 9</figref>. The controller function <b>250</b> is a set of software logic that can reside in the processor <b>203</b> and memory <b>211</b> of a number of different base units <b>200</b> within the security network <b>400</b>, including within the base unit <b>200</b>. If the base unit <b>200</b> memory is of an appropriate type and size, the memory <b>211</b> can contain a controller function <b>250</b>, consisting of both program code and configuration data. The program code will generally contain both controller function <b>250</b> code common to all devices as well as code specific to the base unit <b>200</b> type. For example, a base unit <b>200</b> will have certain device specific hardware that requires matching code, and a gateway <b>300</b> may have different device specific hardware that requires different matching code.

0138When multiple base units <b>200</b> are installed in a system, the controller functions <b>250</b> in the different devices become aware of each other, and share configuration data and updated program code. The updated program code can consist of either a later released version of the program code, or can consist of device specific code or parameters. For example, if a new type of base unit <b>200</b> is developed and then installed into an existing network, the older base units <b>200</b> in the system may require updated program code or parameters in order to effectively manage the new base unit <b>200</b>.

0139Each controller function <b>250</b> in each device can communicate with all other controller functions <b>250</b> in all other base units <b>200</b> as shown in <figref idref="DRAWINGS">FIG. 9</figref>. The purpose of replicating the controller function <b>250</b> on multiple base units <b>200</b> is to provide a high level of redundancy throughout the entire security network <b>400</b>, and to reduce or eliminate possible points of failure (whether component failure, power failure, or disablement by an intruder). The controller functions <b>250</b> implemented on each base unit <b>200</b> perform substantially the same common functions, therefore the chances of system disablement by an intruder are fairly low.

0140When there are multiple controller functions <b>250</b> installed in a single security network <b>400</b>, the controller functions <b>250</b> arbitrate among themselves to determine which controller function <b>250</b> shall be the master controller <b>251</b> for a given period of time. The preferred arbitration scheme consists of a periodic self-check test by each controller function <b>250</b>, and the present master controller <b>251</b> may remain the master controller <b>251</b> as long as its own periodic self-check is okay and reported to the other controller functions <b>250</b> in the security network <b>400</b>. If the present master controller <b>251</b> fails its self-check test, or has simply failed for any reason or been disabled, and there is at least one other controller function <b>250</b> whose self-check is okay, the failing master controller <b>251</b> will abdicate and the other controller function <b>250</b> whose self-check is okay will assume the master controller <b>251</b> role. In the initial case or subsequent cases where multiple controller functions <b>250</b> (which will ideally be the usual case) are all okay after periodic self-check, then the controller functions <b>250</b> may elect a master controller <b>251</b> from among themselves by each choosing a random number from a random number generator, and then selecting the controller function <b>250</b> with the lowest random number. There are other variations of arbitration schemes that are widely known, and any number are equally useful without deducting from the inventiveness of permitting multiple controller functions <b>250</b> in a single security network <b>400</b>, as long as the result is that in a multi-controller function <b>250</b> system, no more than one controller function <b>250</b> is the master controller <b>251</b> at any one time. In a multi-controller function <b>250</b> system, one controller function <b>250</b> is master controller <b>251</b> and the remaining controller functions <b>250</b> are slave controllers, keeping a copy of all parameters, configurations, tables, and status but generally not duplicating the actions of the master controller <b>251</b>.

0141In a system with multiple controller functions <b>250</b>, the security network <b>400</b> can receive updated program code and selectively update the controller function <b>250</b> in just one of the base units. If the single base unit <b>200</b> updates its program code and operates successfully, then the program code can be updated in other base units. If the first base unit <b>200</b> cannot successfully update its program code and operate, then the first base unit <b>200</b> can revert to a copy of older program code still stored in other base units. Because of the distributed nature of the controller functions <b>250</b>, the security network <b>400</b> of the present invention does not suffer the risks of prior art alarm panels which had only one controller.

0142Each controller function <b>250</b> typically performs some or all of the following major logic activities, although the following list is not meant to be limiting:

0143configuration of the security network <b>400</b> whereby each of the other components are identified, enrolled, and placed under control of the master controller <b>251</b>,

0144receipt and interpretation of daily operation commands executed by the homeowner or building occupants including commands whereby the system is placed, for example, into armed or monitoring mode or disarmed for normal building use,

0145communications with other controller functions <b>250</b>, if present, in the system including exchange of configuration information and daily operation commands as well as arbitration between the controller functions <b>250</b> as to which controller function <b>250</b> shall be the master controller <b>251</b>,

0146communications with various external networks <b>410</b> for purposes such as sending and receiving messages, picture and audio files, new or updated program code, commands and responses, and similar functions,

0147communications with base units <b>200</b> and transponders <b>100</b> in the security network <b>400</b> including the sending of various commands and the receiving of various responses and requests,

0148processing and interpretation of data received from the base units <b>200</b> including data regarding the receipt of various signals from the sensors <b>600</b> and <b>620</b> and transponders <b>100</b> within communications range of each base unit,

0149monitoring of each of the sensors, both directly and indirectly, to determine, for example, whether a likely intrusion has occurred, whether glass breakage has been detected, or whether motion has been detected by a microwave- and/or passive infrared-based device,

0150deciding, based upon the configuration of the security network <b>400</b> and the results of monitoring activity conducted by the controller function <b>250</b>, whether to cause an alert or take another event based action,

0151causing an alert, if necessary, by some combination of audible indication such as via a siren device <b>551</b>, or using a gateway <b>300</b> to dial through the public switched telephone network (PSTN) <b>403</b> to deliver a message to an emergency response agency <b>460</b>, or sending a message through one or more Ethernet <b>401</b>, internet <b>405</b>, and/or commercial mobile radio services (CMRS) <b>402</b> to an emergency response agency <b>460</b>.

0152The controller function <b>250</b> offers an even higher level of security that is particularly attractive to marketing the inventive security network <b>400</b> to apartment dwellers. Historically, security systems of any type have not been sold and installed into apartments for several reasons. Apartment dwellers are more transient than homeowners, making it difficult for the dweller or an alarm services company to recoup an investment from installing a system. Of larger issue, though, is the small size of apartments relative to houses. The smaller size makes it difficult to effectively hide the alarm panel of prior art security systems, making it vulnerable to discovery and then disconnection or destruction during the pre-alert period. The pre-alert period of any security system is the time allowed by the alarm panel for the normal homeowner to enter the home and disarm the system by entering an appropriate code or password into a keypad. This pre-alert time is often set to 30 seconds to allow for the fumbling of keys, the carrying of groceries, the removal of gloves, etc. In an apartment scenario, 30 seconds is a relatively long time in which an intruder can search the apartment seeking the alarm panel and then preventing an alert. Therefore, security systems have not been considered a viable option for most apartments. Yet, approximately 35% of the households in the U.S. live in apartments (or other multi-family dwelling units) and their security needs are not less important than those of homeowners.

0153The inventive security network <b>400</b> may include an additional remote monitoring function in the controller function <b>250</b>, which can be selectively enabled at the discretion of the system user. The controller function <b>250</b> includes a capability whereby the controller function <b>250</b> of one base unit <b>200</b> can send a message to a designated cooperating base unit <b>200</b> at the time that a pre-alert period begins and again at the time that the security network <b>400</b> has been disabled by the normal user, such as the apartment dweller, by entering the normal disarm code. The designated cooperating base unit <b>200</b> may be located anywhere within RF range of the first base unit <b>200</b> such as for example another apartment, another building, or a secure room within the building. Furthermore, the controller function <b>250</b> of one base unit <b>200</b> can send a different message to the same designated cooperating base unit <b>200</b> if the normal user enters an abnormal disarm code that signals distress, such as when, for example, an intruder has forced entry by following the apartment dweller home and using a weapon to force the apartment dweller to enter her apartment with the intruder and disarm the security network <b>400</b>.

0154In logic flow format, the remote monitoring function operates as shown in <figref idref="DRAWINGS">FIG. 12</figref> and described in more detail below, assuming that the function has been enabled by the user:

0155an intrusion is detected in the building, such as the apartment,

0156the controller function <b>250</b> in a first base unit <b>200</b> begins a pre-alert period,

0157the controller function <b>250</b> in the first base unit <b>200</b> sends a message to a designated cooperating base unit <b>200</b> whereby the message indicates the identity of the security network <b>400</b> and the transition to pre-alert state,

0158the designated cooperating base unit <b>200</b> begins a timer (for example 30 seconds or any reasonable period allowing for an adequate pre-alert time),

0159if the person causing the intrusion is a normal user under normal circumstances, the normal user will enter or speak the normal disarm code or password,

0160the controller function <b>250</b> in the first base unit <b>200</b> ends the pre-alert period, and enters a disarmed state,

0161the controller function <b>250</b> in the first base unit <b>200</b> sends a message to the cooperating base unit <b>200</b>, whereby the message indicates the identity of the security network <b>400</b> and the transition to disarm state,

0162if the person causing the intrusion is an intruder who does not know the disarm code and/or disables and/or destroys the first base unit <b>200</b> containing the controller function <b>250</b> of the security network <b>400</b>,

0163the timer at the cooperating base unit <b>200</b> reaches the maximum time limit (30 seconds in this example) without receiving a message from the controller function <b>250</b> in the first base unit <b>200</b> indicating the transition to disarm state,

0164the cooperating base unit <b>200</b> may remotely cause an alert indicating that a probable intrusion has taken place at the location associated with the identity of the security network <b>400</b>,

0165if the person causing the intrusion is an authorized user under distressed circumstances (i.e., gun to back), the authorized user enters or speaks an abnormal disarm code or password indicating distress,

0166the controller function <b>250</b> in the first base unit <b>200</b> sends a message to the cooperating base unit <b>200</b>, whereby the message indicates the identity of the security network <b>400</b> and the use of an abnormal disarm code or password indicating distress,

0167the cooperating base unit <b>200</b> may remotely cause an alert indicating that an intrusion has taken place at the location associated with the identity of the security network <b>400</b> and that the authorized user is present at the location and under distress.

0168As can be readily seen, this inventive remote monitoring function now enables the installation of this inventive security network <b>400</b> into apartments without the historical risk that the system can be rendered useless by the discovery and disablement or destruction by the intruder. With this function enabled, even if the intruder were to disable or destroy the system, a remote alert could still be signaled because a message indicating a transition to disarm state would not be sent, and a timer would automatically conclude remotely at the designated processor. This function is obviously not limited to just apartments and could be used for any building.

0169With a wireless module <b>311</b> or <b>312</b>, WiFi module <b>313</b>, or Ethernet module <b>313</b> installed, a gateway <b>300</b> can also be configured to send either an SMS-based message through the CMRS <b>402</b> or an email message through a WiFi network <b>404</b> or Ethernet network <b>401</b> to the Internet <b>405</b> to any email address based upon selected user events. For example, an individual away from home during the day may want a message sent to his pager, wireless phone, or office email on computer <b>450</b> if the inventive security network <b>400</b> is disarmed at any point during the day when no one is supposed to be at home. Alternately, a parent may want a message sent when a child has returned home from school and disarmed the security network <b>400</b>. Perhaps a homeowner has provided a temporary disarm code or password to a service company scheduled to work in the home, and the homeowner wants to receive a message when the work personnel have arrived and entered the home. By assigning different codes or passwords to different family members and/or work personnel, the owner of the security network <b>400</b> can discriminate among the persons authorized to disarm the system. Any message sent, as described herein, can contain an indication identifying the code/password and/or the person that entered the disarm code/password. The disarm code/password itself is typically not sent for the obvious security reasons, just an identifier associated with the code.

0170The gateway <b>300</b> can send or receive updated software, parameters, configuration, or remote commands, as well as distribute these updated software, parameters, configuration, or remote commands to other controller functions <b>250</b> embedded in other base units <b>200</b>. For example, once the security network <b>400</b> has been configured, a copy of the configuration, including all of the table entries, can be sent to a remote processor <b>461</b> for both backup and as an aid to responding to any reported emergency. If, for any reason, all of the controller functions <b>250</b> within the security network <b>400</b> ever experienced a catastrophic failure whereby its configuration were ever lost, the copy of the configuration stored at the remote processor <b>461</b> could be downloaded to a restarted or replacement controller function <b>250</b>. Certain parameters, such as those used in glass breakage detection, can be downloaded to the controller function <b>250</b> and then propagated, in this example, to the appropriate glass breakage detection functions that may be contained within the system. Therefore, for example, if a homeowner were experiencing an unusual number of false alarm indications from a glass breakage detection function, remote technical personnel could remotely make adjustments in certain parameters and then download these new parameters to the controller function <b>250</b>. Additionally, the operating parameters for new base units <b>200</b> can also be downloaded to the controller function <b>250</b>. For example, if a homeowner added a new base unit <b>200</b> to the security network <b>400</b> several years after initial installation, the parameters for this new type of base unit <b>200</b> might not exist in the controller function <b>250</b>. The security network <b>400</b> could obtain the parameters associated with the new base unit <b>200</b> from a site designated by the manufacturer.

0171The controller function <b>250</b> can also report periodic status and/or operating problems detected by the system to the emergency response agency <b>460</b>, the manufacturer of the system, or a similar entity. One example of the usefulness of this function is that reports of usage statistics, status, and/or problems can be generated by an example emergency response agency <b>460</b> and a copy provided to the customer as part of his monthly bill. Furthermore, the usage statistics of similarly situated customers can be compared and analyzed for any useful patterns. Technicians at an emergency response agency <b>460</b>, the manufacturer of the system, or a similar entity can use any collected data to diagnose problems and make changes to the configuration, parameters, or software of security network <b>400</b> and remotely download these changes to the security network <b>400</b>. This may eliminate the need for a technician visit to a customer's home or other building.

0172Any base unit <b>200</b> may include an acoustic transducer <b>210</b> (shown in <figref idref="DRAWINGS">FIG. 3</figref>). The acoustic transducer <b>210</b> preferably supports both the reception of sounds waves and the emission of sound waves such that the acoustic transducer <b>210</b> can also be used for functions such as glass breakage detection, fire alarm detection, two-way audio, the sounding of tones and alerts, voice recognition, and voice response (i.e., spoken word responses to commands). While shown as a single block in <figref idref="DRAWINGS">FIG. 3</figref>, the acoustic transducer <b>210</b> can be implemented with a single combined component or with a separate input transducer (i.e., microphone) and output transducer (i.e., speaker and/or piezo).

0173It is preferred that microprocessor <b>203</b> be able to read acoustic data from the acoustic transducer <b>210</b> in order to analyze the data for specific patterns. For example, it would be advantageous for the microprocessor <b>203</b> to detect specific speech patterns for use in voice recognition. Similarly, the microprocessor <b>203</b> may look for patterns that indicate the sound of breaking glass or an alerting smoke detector or fire alarm. It is also preferred that microprocessor <b>203</b> be able to send acoustic data to the acoustic transducer <b>210</b> in order to create sounds for feedback or alerting, or to output pre-stored words for voice response. The memory <b>211</b> should ideally contain sufficient data space for the storage of both patterns for recognition and output sounds and words.

0174An example embodiment of a gateway <b>300</b> is a USB gateway <b>510</b>. The USB gateway <b>510</b> includes common characteristics and embodiments with the base unit <b>200</b> including high power RF communications and communications with transponders <b>100</b>. Thus, if a USB gateway <b>510</b> has been installed in a room, it may not be necessary for a separate base unit <b>200</b> to also be installed in a room in order to monitor the transponders <b>100</b>.

0175An interface mechanism available for use with the security network <b>400</b> is a USB gateway <b>510</b> that enables a desktop or laptop computer to be used for downloading, uploading, or editing the configuration stored in the controller functions <b>250</b>. The USB gateway <b>510</b> connects to and may obtain power from the Universal Serial Bus (USB) port commonly installed in most computers <b>450</b> today. The USB gateway <b>510</b> can convert signals from the USB port to backscatter modulation or high power RF communications with a base unit <b>200</b> or gateway <b>300</b>, thereby providing access to the configuration data stored by the controller functions <b>250</b>. A software program provided with the USB gateway <b>510</b> enables the user to access the USB gateway <b>510</b> via the USB port, and display, edit, or convert the configuration data. In this manner, authorized users have an easy mechanism to create labels for each of the base units <b>200</b>, gateways <b>300</b>, and transponders <b>100</b>. For example, a particular transponder <b>100</b> may be labeled “Living Room Window” so that any alert generated by the security network <b>400</b> can identify by label the room in which the intrusion has occurred. The labels created for the various devices can also be displayed on the display <b>266</b> to show, for example, which zones are in an open or closed state.

0176Another example embodiment of a base unit <b>200</b> is an email device <b>530</b>. The security network <b>400</b> can support an email device <b>530</b> that uses high power RF communications to communicate with the base units <b>200</b> and gateways <b>300</b>. This email device <b>530</b>, which can take the form of a palm-type organizer or other forms, may typically be used to send and receive email via the modules of a gateway <b>300</b>. As described earlier, the various devices in the security network <b>400</b> self form a network, thereby enabling messages to originate on any base unit <b>200</b> and terminate on any capable base unit <b>200</b>. Therefore, it is not necessary that the email device <b>530</b> be near a gateway <b>300</b>. If necessary, messages can be received via a gateway <b>300</b>, routed through multiple base units <b>200</b>, and then terminated at the email device <b>530</b>. The primary advantage of including an email device <b>530</b> in the security network <b>400</b> is to provide the homeowner a device that is always on and available for viewing. There are a growing number of wireless phones in use today capable of sending and receiving SMS messages. The email device <b>530</b> provides a convenient, always-on device whereby family members can sent short messages to each other. For example, one spouse can leave a message for another spouse before leaving work. The functions of the email device may be combined with the functions of another device, such as a keypad, to advantageously form an integrated device.

0177Another example embodiment of a gateway <b>300</b> is a WiFi gateway <b>520</b>. As an alternative to using a USB gateway <b>510</b>, the security network <b>400</b> also supports a WiFi gateway <b>520</b>. WiFi, also known as 802.11b, is becoming a more prevalent form of networking computers. Recently, Intel made available a new chip called Centrino by which many new computers will automatically come equipped with WiFi support. Therefore, rather than using a USB gateway <b>510</b> that connects to a port on the computer <b>450</b>, a gateway <b>300</b> may include a WiFi module <b>313</b>. The WiFi gateway <b>520</b> can provide either local access from a local PC <b>450</b> (assuming that the local PC supports WiFi) to the security network <b>400</b>, or alternately from the security network <b>400</b> to a public WiFi network <b>404</b>. It is expected that in the near future, some neighborhoods will be wired with public WiFi networks <b>404</b>. These public WiFi networks <b>404</b> will provide another alternative access means to the internet from homes (in addition to cable modems <b>440</b> and DSL <b>441</b>, for example). There may be users, therefore, that may prefer the security network <b>400</b> to provide alerts through this network rather than a PSTN <b>403</b> or CMRS <b>402</b> network. In the event these public WiFi networks <b>404</b> become prevalent, then the security network <b>400</b> can offer the email access described above through these networks as well. The WiFi gateway <b>520</b> primarily acts as a protocol converter between the chosen modulation and protocol used within the security network <b>400</b> and the 802.11b standard. In addition to the protocol conversion, the WiFi gateway <b>520</b> also provides a software-based security barrier similar to a firewall to prevent unauthorized access to the security network <b>400</b>.

0178Any base unit <b>200</b> may also include a camera <b>213</b>. A typical type of camera <b>213</b> may be a miniature camera of the type commonly available in mobile phones and other consumer electronics. Low cost miniature cameras are widely available for PC and wireless phone use, and formats (i.e., JPEG) for transmitting pictures taken by these miniature cameras are also widely known. By recording sequential images taken over a short period of time, a time lapse record may be created. Through one or more of the gateways <b>300</b>, the security network <b>400</b> can access external networks as well as be accessed through these same networks. Some users may find it useful to be able to visually or audibly monitor their home or building remotely. Therefore, the security network <b>400</b> also supports base units <b>200</b> including cameras <b>213</b> and/or audio transducers <b>210</b> that enable a user to remotely see and/or hear what is occurring in a home or building. Each of the base units <b>200</b> can be individually addressed since each is typically provided with a unique identity. When a security network <b>400</b> causes an alert, an emergency response agency <b>460</b> or an authorized user can be contacted. In addition to reporting the alert, as well as the device (i.e., identity of the transponder <b>100</b>) causing the alert, the security network <b>400</b> can be configured to provide pictures and/or audio clips of the activity occurring within the security network <b>400</b>. Base units <b>200</b> with cameras <b>213</b> and/or audio transducers <b>210</b> will be particularly useful in communities in which the emergency response agency <b>460</b> requires confirmation of intrusion prior to dispatching police.

0179There are multiple uses for the audio <b>210</b> and camera <b>213</b> support in the security network <b>400</b> in addition to alarm verification by an emergency response agency <b>460</b>. A caregiver can check in on the status of an elderly person living alone using the audio and/or camera capabilities of the security network <b>400</b>. A family on a trip can check in on the activities of a pet left at home. The owner of a vacation home can periodically check in on the property during the winter months when the vacation home is otherwise unoccupied.

0180Certain base units <b>200</b> may be configured with additional memory <b>211</b> for the purpose of storing pictures and/or audio files. By combining within a security network <b>400</b> the audio <b>210</b> and/or camera <b>213</b> capability with a USB gateway <b>300</b> and a local PC a user can store picture and audio files on the PC to provide a continuous record of activities in the home. As an alternative to storing pictures on a local PC, a base unit <b>200</b> can be provided with a large enough memory <b>211</b> to contain a file system wherein the file system stores pictures periodically taken by one or more cameras in the security network <b>400</b>. One way in which the memory of a base unit <b>200</b> can be expanded is through the use of well-known flash memory. For example, flash memory modules are available in a variety of pre-packaged formats such as PCMCIA, Compact Flash, or USB, so a base unit <b>200</b> can be implemented to accept modules in these formats. The pictures and/or audio files in the file system can be accessed later to retrieve pictures taken at particular times. These files can be accessed in a number of ways. If the memory <b>211</b> is contained in a removable flash memory module, the module can be removed and inserted into another device such as a PC that can read the files. Alternately, the files in the memory <b>211</b> can be accessed through a gateway <b>300</b>. For example, a local PC can use a USB gateway <b>510</b> or WiFi gateway <b>520</b> or an emergency response agency can use a telephone, wireless, or Ethernet based connection.

0181One advantageous base unit <b>200</b> in which a camera <b>213</b> can be included is a base unit <b>200</b> built into the physical form of a smoke/fire/CO detector <b>590</b> or a detector collar <b>591</b> as shown in <figref idref="DRAWINGS">FIG. 15</figref>. Since detectors are generally mounted on ceilings, the inclusion of camera <b>213</b> capability into a ceiling mounted base unit <b>200</b> built into the physical form of a smoke/fire/CO detector <b>590</b> or smoke detector collar <b>591</b> will provide the camera <b>213</b> with a wide angle of view with little likely viewing obstruction. A base unit <b>200</b> built into the physical form of a smoke/fire/CO detector <b>590</b> can include smoke, fire, or CO detection capability <b>212</b>. The detection technology for smoke, fire, and/or CO is widely known and available. A base unit <b>200</b> built into the physical form of a detector collar <b>591</b> would likely not require smoke, fire, or CO detection <b>212</b> capability since the state of the attached smoke, fire, or CO can be detected by the base unit <b>200</b>.

0182The inventive security network <b>400</b> does not require all detectors <b>590</b> installed in a home to include a base unit <b>200</b> as defined in this specification. Certain manufacturers, such as Firex for example, already provide families of low cost smoke detectors that have a wired communications capability; that is, if one smoke detector detects smoke and causes an audible alert, all smoke detectors that are wired to the detecting smoke detector also cause an audible alert. Using the present invention, one of the example Firex smoke detectors can be replaced with a base unit <b>200</b> of the inventive security network <b>400</b>, and if any of the Firex family of smoke detectors causes an alert and sends a communications via the standard Firex wired communications, the base unit <b>200</b> of the inventive security network <b>400</b> will receive the same communications as all Firex smoke detectors on the same circuit, and the inventive security network <b>400</b> can cause its own alert using its own audible capability and/or any gateway <b>300</b> devices installed in the inventive security network <b>400</b>. This ability to convert the wired communications from an existing example Firex network of smoke detectors into an appropriate communications within the inventive security network <b>400</b> obviates the need for a user to replace all of the smoke detectors in a home when installing an inventive security network <b>400</b>. While this example has been given using smoke detectors, it is understood that this example is extensible to fire detectors, carbon monoxide (CO) detectors, and other similar detection devices typically used in residential and commercial buildings.

0183If the designer does not wish to design a base unit <b>200</b> including smoke/fire/CO detect capability <b>212</b>, then the designer can place the base unit <b>200</b> functionality into a detector collar <b>591</b> that it placed between an example smoke/fire/CO detector <b>590</b> and the mounting plate <b>592</b> attached to the ceiling <b>704</b>. An AC powered smoke detector usually requires that an electrical box be installed into the ceiling. The mounting plate <b>592</b> is attached to the electrical box in the ceiling and a connector protrudes from the electrical box. The smoke/fire/CO detector <b>590</b> is then typically connected to the connector, and then snapped onto the mounting plate <b>592</b>. Under the present invention, a detector collar <b>591</b> can be placed between the mounting plate <b>592</b> and the smoke/fire/CO detector <b>590</b>. The detector collar <b>591</b> can provide the physical volume to contain the base unit <b>200</b> functionality as well as intercept the AC power and the communications wire that are contained in the connector protruding from the electrical box. By intercepting and detecting the state of the communications wire, the base unit <b>200</b> can detect any changes in state, such as the signaling of an alert. Rather than intercepting the communications wire, or in the case of a sensor that does not include a separate communications wire, the base unit <b>200</b> can also sense the audio signal typically put out by an example smoke/fire/CO detector <b>590</b>. These audio signals are generally designed to generate audio power of approximately 85 dB at 10 feet in various predetermined and distinctive patterns. The base unit <b>200</b> can include an appropriate audio transducer <b>210</b> that can sense the presence or absence of the volume and/or distinctive pattern of the audio output by the smoke/fire/CO detector <b>590</b>. In any of the example cases, when the base unit <b>200</b> detects an alert state being signaled by an example smoke/fire/CO detector <b>590</b>, the base unit <b>200</b> can send a communication to the master controller <b>251</b> in the security network <b>400</b>. The security network <b>400</b> can then send an alert to an emergency response agency <b>460</b> or take any other predetermined action configured in the security network <b>400</b> by the end user.

0184Note that while smoke detectors and Firex have been used as examples, other types of sensors and other brands/manufacturers can be substituted into this specification without detracting from the inventive nature. It is also not required that full base unit <b>200</b> functionality be placed into the smoke/fire/CO detector <b>590</b> or smoke detector collar <b>591</b>. If no camera <b>213</b> or audio <b>210</b> capability is desired, then a transponder <b>100</b> can be implemented in the smoke/fire/CO detector <b>590</b> or smoke detector collar <b>591</b> instead of a base unit <b>200</b>. In <figref idref="DRAWINGS">FIG. 15</figref>, both the base unit <b>200</b> and transponder <b>100</b> are shown with dashed lines to show the optional choices that can be made.

0185The base unit <b>200</b> can include several options that increase both the level of security and functionality in the inventive security network <b>400</b>. One option enhances the base unit <b>200</b> to include an acoustic transducer <b>210</b> capable of receiving and/or emitting sound waves that enables a glass breakage detection capability in the base unit <b>200</b>. Glass breakage sensors have been widely available for years for both wired and wireless prior art security networks. However, they are available only as standalone sensors typically selling for $30 to $50 or more. Of course, in a hardwired system, there is also the additional labor cost of installing separate wires from the alarm panel to the sensor. The cost of the sensors generally limits their use to just a few rooms in a house or other building. The cost is due in part to the need for circuits and processors dedicated to just analyzing the sound waves.

0186Since the base unit <b>200</b> already contains a power supply <b>207</b> and a processor <b>203</b> the only incremental cost of adding the glass breakage detection capability is the addition of the acoustic transducer <b>210</b> and the software to analyze sound patterns for any of the distinctive patterns of breaking glass. With the addition of this option, glass breakage detection can be available in every room in which a base unit <b>200</b> has been installed.

0187Glass breakage detection is performed by analyzing received sound waves to look for certain sound patterns distinct in the breaking of glass. These include certain high frequency sounds that occur during the impact and breaking of the glass and low frequencies that occur as a result of the glass flexing from the impact. The sound wave analysis can be performed by any number of widely known signal processing techniques that permit the filtering of received signals and determination of signal peaks at various frequencies over time.

0188One advantage of the present invention over prior art standalone glass breakage sensors is the ability to adjust parameters in the field. Because glass breakage sensors largely rely on the receipt of audio frequencies, they are susceptible to false alarms from anything that generates sounds at the right combination of audio frequencies. Therefore, there is sometimes a requirement that each glass breakage sensor be adjusted after installation to minimize the possibility of false alarms. In some cases, no adjustment is possible in prior art glass breakage detection devices because algorithms are permanently stored in firmware at the time of manufacture. Because the glass breakage detection of the present invention is performed by the base units, which include or are in communication with a controller function <b>250</b>, the controller function <b>250</b> can alter or adjust parameters used by the base unit <b>200</b> in glass breakage detection. For example, the controller function <b>250</b> can contain tables of parameters, each of which applies to different building construction materials or window types. The user can select the appropriate table entry during system configuration, or select another table entry later after experience has been gained with the installed security network <b>400</b>. Furthermore, the controller function <b>250</b> can contact an appropriate database via a gateway <b>300</b> that is, for example, managed by the manufacturer of the security network <b>400</b> to obtain updated parameters. There is, therefore, significant advantage to this implementation of glass breakage detection, both in the cost of device manufacture and in the ability to make adjustments to the processing algorithms used to analyze the sound waves.

0189In a manner similar to glass breakage detection above, the received sound waves can be analyzed to look for certain (usually very high decibel) sound patterns distinct in alerting smoke detectors, fire alarms, carbon monoxide detectors, and similar local alerting devices. When one or more base units <b>200</b> detect the distinct sound patterns from any of these local alerting devices, the controller function <b>250</b> can send an appropriate message via a gateway <b>300</b> to an emergency response agency <b>460</b>.

0190The addition of the acoustic transducer <b>210</b>, with both sound input and output capability, to the base unit <b>200</b> for the glass breakage option also allows the base unit <b>200</b> to be used by an emergency response agency <b>460</b> as a distributed microphone to listen into the activities of an intruder. Rather than analyzing the sound waves, the sound waves can be digitized and sent to the gateway <b>300</b>, and then by the gateway <b>300</b> to the emergency response agency <b>460</b>. After the gateway <b>300</b> has sent an alert message to the emergency response agency <b>460</b>, the audio transducer can be available for use in an audio link. This two-way audio capability through the acoustic transducer <b>210</b> can be useful for more than just listening by an emergency response agency <b>460</b>. Parents who are not home can listen into the activities of children who might be home. Similarly, a caregiver can use the two-way audio to communicate with an elderly person who might be living alone.

0191In a similar manner, the base unit <b>200</b> can contain optional algorithms for the sensing of motion in the room. Like glass breakage sensors, prior art motion sensors are widely available as standalone devices. Prior art motion sensors suffer from the same disadvantages cited for standalone glass breakage sensors, that is they are typically standalone devices requiring dedicated processors, circuits, and microwave generators. However, the base unit <b>200</b> already contains all of the hardware components necessary for generating and receiving the radio wave frequencies commonly used in detecting motion; therefore the base unit <b>200</b> only requires the addition of algorithms to process the signals for motion in addition to performing its reading of the transponders <b>100</b>. Different algorithms are available for motion detection at microwave frequencies. One such algorithm is Doppler analysis. It is a well-known physical phenomenon that objects moving with respect to a transmitter cause a reflection with a shift in the frequency of the reflected wave. While the shift is not large relative to the carrier frequency, it is easily detectable. Therefore, the base unit <b>200</b> can perform as a Doppler radar by the rapid sending and receiving of radio pulses, with the subsequent measurement of the reflected pulse relative to the transmitted pulse. People and animals walking at normal speeds will typically generate Doppler shifts of 5 Hz to 50 Hz, depending on the speed and direction of movement relative to the base unit <b>200</b> antenna <b>206</b>. The implementation of this algorithm to detect the Doppler shift can, at the discretion of the designer, be implemented with a detection circuit or by performing signal analysis using the processor of the base unit <b>200</b>. In either case, the object of the implementation is to discriminate any change in frequency of the return signal relative to the transmitted signal for the purpose of discerning a Doppler shift. The base unit <b>200</b> is capable of altering its transmitted power to vary the detection range of this motion detection function.

0192These motion detection functions can occur simultaneously with the reading of passive transponders <b>150</b>. Because the passive transponders <b>150</b> are fixed relative to the base units, no unintended shift in frequency will occur in the reflected signal. Therefore, for each transmitted burst to a passive transponder <b>150</b>, the base unit <b>200</b> can analyze the return signal for both receipt of data from the passive transponder <b>150</b> as well as unintended shifts in frequency indicating the potential presence of a person or animal in motion.

0193By combining the above functions, the base unit <b>200</b> in one example single integrated package may be capable of (i) communicating with other base units <b>200</b> using high power RF communications, (ii) communicating with transponders using low power RF and backscatter wireless communications, (iii) detecting motion via Doppler analysis at microwave frequencies, (iv) detecting glass breakage and/or high decibel alerts via sound wave analysis of acoustic waves received via an audio transducer <b>210</b>, and (v) providing a two-way audio link to an emergency response agency <b>460</b> via an audio transducer <b>210</b> and via a gateway <b>300</b>. This base unit <b>200</b> achieves significant cost savings versus prior art security networks <b>400</b> through the avoidance of new wire installation and the sharing of communicating and processing circuitry among the multiple functions. Furthermore, because the base units <b>200</b> are under the control of a single master controller <b>251</b>, the performance of these functions can be coordinated to minimize interference, and provide spatial diversity and redundant confirmation of received signals.

0194A microwave frequency motion detector implemented in the base unit <b>200</b> is only a single detection technology. Historically, single motion detection technologies, whether microwave, ultrasonic, or passive infrared, all suffer false positive indications. For example, a curtain being blown by a heating vent can occasionally be detected by a Doppler analysis motion detector. Therefore, dual technology motion detectors are sometimes used to increase reliability—for example by combining microwave Doppler with passive infrared so that motion by a warm body is required to trigger an alert. The inventive security network <b>400</b> implements a novel technique to implement dual technology motion sensing in a room without the requirement that both technologies be implemented into a single package.

0195Existing dual technology sensors implement both technologies into a single sensor because the sensors are only capable of reporting a “motion” or “no motion” condition to the alarm panel. This is fortunate, because present prior art alarm panels are only capable of receiving a “contact closed” or “contact open” indication. Therefore, all of the responsibility for identifying motion must exist within the single sensor package. The inventive controller function <b>250</b> can receive communications with a passive infrared sensor <b>570</b> mounted separately from the base unit <b>200</b>. Therefore, if in a single room, the base unit <b>200</b> is detecting motion via microwave Doppler analysis and a passive infrared sensor <b>570</b> is detecting the presence of a warm body <b>710</b> as shown in <figref idref="DRAWINGS">FIG. 6</figref>, the master controller <b>251</b> can interpret the combination of both of these indications in a single room as the likely presence of a person.

0196One embodiment of this passive infrared sensor <b>570</b> is in the form of a light switch <b>730</b> with cover <b>731</b> as shown in <figref idref="DRAWINGS">FIG. 14A</figref>. Most major rooms have at least one existing light switch <b>730</b>, typically mounted at an average height of 55″ above the floor. This mounting height is above the majority of furniture in a room, thereby providing a generally clear view of the room. Passive infrared sensors have previously been combined with light switches <b>730</b> so as to automatically turn on the light when people are in the room. More importantly, these sensor/switches turn off the lights when everyone has left, thereby saving electricity that would otherwise be wasted by lighting an unoccupied room. Because the primary purpose of these existing devices is to provide local switching, the devices cannot communicate with central controllers such as existing alarm panels.

0197The passive infrared sensor <b>570</b> that operates with the inventive security network <b>400</b> includes any of high power RF communications, low power RF communications, or modulated backscatter communications to permit the passive infrared sensor <b>570</b> to communicate with one or more controller functions <b>250</b> in base units <b>200</b> and be under control of the master controller <b>251</b>. The passive infrared sensor <b>570</b> can therefore be combined with a transponder <b>100</b> or included in a base unit <b>200</b>. At the time of system installation, the master controller <b>251</b> is configured by the user thereby identifying the rooms in which the base units <b>200</b> are located and the rooms in which the passive infrared sensors <b>570</b> are located. The master controller <b>251</b> can then associate each passive infrared sensor <b>570</b> with one or more base units <b>200</b> containing microwave Doppler algorithms. The master controller <b>251</b> can then require the simultaneous or near simultaneous detection of motion and a warm body, such as a person <b>710</b>, before interpreting the indications as a probable person in the room.

0198Because each of the base units <b>200</b> and passive infrared sensors <b>570</b> are under control of the master controller <b>251</b>, portions of the circuitry in these devices can be shut down and placed into a sleep mode during normal occupation of the building. Since prior art motion sensors are essentially standalone devices, they are always on and are always reporting a “motion” or “no motion” condition to the alarm panel. Obviously, if the alarm panel has been placed into a disarmed state because, for example, the building is being normally occupied, then these “motion” or “no motion” conditions are simply ignored by the alarm panel. But the sensors continue to use power, which although the amount may be small, is still a waste of AC or battery power. Furthermore, it is well known in the study of reliability of electronic components that “power on” states generate heat in electronic components, and it is heat that contributes to component aging and possible eventual failure.

0199The present security network <b>400</b> can selectively shut down or at least slow down the rate of the radiation from the base units <b>200</b> when the security network <b>400</b> is in a disarmed mode, or if the homeowner or building owner wants the security network <b>400</b> to operate in a perimeter only mode without regard to the detection of motion. By shutting down the radiation and transmissions used for motion detection, the security network <b>400</b> is conserving power, extending the potential life of the components, and reducing the possibility of interference between the base unit <b>200</b> and other products that may be operating in the same unlicensed band. This is advantageous because, for example, while people are occupying the building they may be using cordless telephones (or wireless LANs, etc.) and want to avoid possible interference from the base unit <b>200</b>. Conversely, when the security network <b>400</b> is armed, there are likely no people in the building, and therefore no use of cordless telephones, and the base units <b>200</b> can operate with reduced risk of interference from the transmissions from cordless telephones.

0200In general, a passive transponder <b>150</b> has two primary functions: manage its wireless communications and monitor a state change of any attached multi-state device. The following description considers the example of a passive transponder <b>150</b> used for monitoring intrusions through a window or door opening. The description can be expanded to include any number of additional examples, however.

0201A passive transponder <b>150</b>, shown in <figref idref="DRAWINGS">FIG. 11</figref>, used with the inventive security network <b>400</b> achieves its advantage over wireless transmitters of prior art security systems through its low cost design. The passive transponder <b>150</b> contains no active radiation circuitry, and therefore the design can be limited to low frequency, low power circuitry. A passive transponder <b>150</b> can be designed with or without a battery, however the design choice will have an impact on the corresponding base unit <b>200</b> design. If a passive transponder <b>150</b> is designed without a battery, the base unit <b>200</b> will be required to transmit at a higher power level in order to generate a high enough electric field to power the passive transponder <b>150</b> circuits. The FCC rule sections cited herein permit the transmission of sufficient power to generate the necessary electric fields, but more expensive circuitry is required in the base unit <b>200</b> to achieve the necessary power levels. If a passive transponder <b>150</b> is designed with a battery, the base unit <b>200</b> can be designed using lower cost circuitry since the transmitted power will be necessary only for the backscatter modulation to work properly. The example considers cases of both with or without a battery contained in the passive transponder <b>150</b>.

0202The passive transponder <b>150</b> typically engages in one or more of the following types of communications:

0203receive parameter information;

0204receive status requests;

0205send status (which may include the state of an attached multi-state device); and

0206send state change information about an attached multi-state device.

0207Because the passive transponder <b>150</b> uses backscatter modulation for sending communications to a base unit, the passive transponder <b>150</b> can never initiate communications as can a base unit <b>200</b>. The passive transponder <b>150</b> can only respond to communications from a base unit <b>200</b>. There are two possible methods by which a base unit <b>200</b> can communicate with a passive transponder: (i) listen first, then talk; or (ii) talk first, then listen.

0208In order to listen, the base unit <b>200</b> transmits a signal that the passive transponder <b>150</b> can backscatter modulate. The signal provided by the base unit <b>200</b> may be modulated or may simply be continuous wave. The communications from the passive transponder <b>150</b> will include the original signal along with the modulation from the passive transponder <b>150</b>. The base unit <b>200</b> will typically subtract the provided signal from the communications returned from the passive transponder <b>150</b>, thereby leaving only the modulation from the passive transponder <b>150</b>.

0209When listening first, the base unit <b>200</b> first transmits its signal that enables communications from the passive transponders <b>150</b>. One or more passive transponders <b>150</b> may elect to backscatter modulate the signal, thereby attempting to send communications to the base unit <b>200</b>. After receiving communications from the one or more passive transponders <b>150</b>, the base unit <b>200</b> may then talk to the passive transponders <b>150</b> if the base unit <b>200</b> has a communication to send. In order to talk, the base unit <b>200</b> transmits a message typically using one of the modulation schemes discussed herein. The transmitted message may include a reply to a communication from the one or more passive transponders <b>150</b>, or may include a command, parameters, or overhead message. One type of reply is a confirmation of the communications received from the passive transponder <b>150</b>. Another type of reply may be that the communications from the passive transponder <b>150</b> failed to be received.

0210When talking first, the base unit <b>200</b> first transmits its message, which then may be followed by the transmission of its signal that enables communications from the passive transponders <b>150</b>. By talking first, the base unit <b>200</b> may direct a particular passive transponder <b>150</b> to communicate in return, or enable any passive transponder <b>150</b> with data to send to communicate in return.

0211Whether or not the passive transponder <b>150</b> contains a battery, it is preferred that the passive transponder <b>150</b> conserve power by operating in a periodic cycle. During a portion of the periodic cycle, it is preferred that the passive transponder <b>150</b> place some or all of its circuits in a low power or zero power state. For example, if the passive transponder <b>150</b> is designed using CMOS based circuitry, any clock used to drive the circuitry can be stopped since CMOS circuits use most of their power during clock or signal transitions. During other portions of the periodic cycle, sufficient circuitry may be enabled such that the passive transponder <b>150</b> can send communications to or receive communications from the base unit <b>200</b>. It is not required that all passive transponders <b>150</b> within a single security network <b>400</b> use the same periodic cycle. Some may have longer cycles than others. If necessary, the controller function <b>250</b> may maintain a table listing each managed passive transponder <b>150</b> and its corresponding periodic cycle.

0212The master controller <b>251</b> in a security network <b>400</b> will typically establish certain operating parameters, which can vary from installation to installation. One of the parameters may be the periodic cycle on which the passive transponders <b>150</b> are to operate. These parameters may vary with the number of active and passive transponders <b>150</b> installed in a system, as well as with the present state of the system. For example, if a security network <b>400</b> is presently in the disarmed state, the master controller <b>251</b> may lengthen the periodic cycle which will cause less frequent communications and conserve more power in the transponders. If the security network <b>400</b> is presently armed, the periodic cycle may be shortened to enable more frequent communications to ensure the integrity of the system.

0213Other parameters that the master controller <b>251</b> may send to a passive transponder <b>150</b> may include identity information about the security network <b>400</b>, identity information for each transponder <b>100</b>, and keys that the passive transponder <b>150</b> may use for encryption or authentication in its communication with a base unit <b>200</b>. In geographic areas where many security networks <b>400</b> may be simultaneously operating, the stored identity information may be useful in maintaining the desired associations between each security network <b>400</b> and its base units <b>200</b>, transponders <b>100</b>, and other active and passive transponders <b>150</b>.

0214Many forms of the passive transponder <b>150</b> will be used to monitor and report upon the state of an attached sensor. For example, one form of the passive transponder <b>150</b> may monitor the open/closed state of a window or door via an intrusion sensor. An intrusion sensor <b>600</b> will typically be a two state device; however the passive transponder <b>150</b> may also support multi-state devices. The passive transponder <b>150</b> will typically report its status and the status of an attached sensor <b>600</b> or <b>620</b> periodically. This periodic status message serves as a “heartbeat” by which the base unit <b>200</b> can supervise each of the installed transponders. The periodicity of the status message may be set as one of the parameters sent by the master controller <b>251</b>. Like the periodic cycle discussed herein, the periodicity of the status messages may vary with the present state of the system.

0215There are two other times when the passive transponder <b>150</b> may report its status: (i) in response to a status request message received from a base unit <b>200</b>, or (ii) if the passive transponder <b>150</b> detects a change in the state of an attached sensor <b>600</b> or <b>620</b>. If the passive transponder <b>150</b> does detect a change in the state of an attached sensor, the passive transponder <b>150</b> may interrupt the communications that may be occurring between a base unit <b>200</b> and a second passive transponder <b>150</b> or the passive transponder <b>150</b> may wait for next available listen signal from a base unit <b>200</b>.

0216Because passive transponders <b>150</b> cannot initiate communications, there may be times when there is a time lag between the time that the passive transponder <b>150</b> detects a change in the state of an attached sensor or device and the time that the passive transponder <b>150</b> communicates with a base unit <b>200</b>. The time lag will typically be based upon the operating parameters of the security network <b>400</b>, and may only be one second or a few seconds. However, the existence of any time lag creates the possibility that the state may change more than once during the time lag. For example, an intruder may open and close a window or door in just a few seconds. Therefore, the passive transponder <b>150</b> may include a latch that records any change in state of an attached sensor or device, however brief the change of state may have been. The latch may be implemented using logic gates, such as a flip flop, or in the state machine or processor of the passive transponder <b>150</b>. The latch typically holds the state change until at least the time that the passive transponder <b>150</b> communicates the state change to a base unit <b>200</b>. The passive transponder <b>150</b> may either maintain the latched state change until the state change has been communicated or may maintain the latched state change until a base unit <b>200</b> sends a command that clears the latch.

0217One form of passive transponder <b>150</b> may typically be provided with an adhesive backing to enable easy attachment to the frame of an opening such as, for example, a window <b>702</b> frame or door <b>701</b> frame. Passive transponder <b>150</b> designs based upon modulated backscatter are widely known and the details of transponder <b>100</b> design are well understood by those skilled in the art. The passive transponder <b>150</b> functions may be implemented within a single chipset or may be implemented as separate components in a circuit on a printed circuit substrate. The passive transponder <b>150</b> receives and interprets commands from the base unit <b>200</b> by typically including circuits for clock extraction <b>103</b> and data modulation <b>104</b>. The manner of implementing clock extraction <b>103</b> and data modulation <b>104</b> will depend upon the type of modulation used for wireless communications from the base unit <b>200</b> to the passive transponder <b>150</b>. For example, if on-off keying is used, the data modulation <b>104</b> circuit can be as simple as a diode. More complicated designs have been shown in circuits such as those disclosed in U.S. Pat. Nos. 6,384,648 and 6,549,064. The microcontroller <b>106</b> can send data and status back to the base unit <b>200</b> by typically using a modulator <b>102</b> to control the impedance of the antenna <b>110</b>. This modulator <b>102</b> may take the form of a single diode or FET or may be more complicated such as the patent examples cited herein. The impedance control alternately causes the absorption or reflection of the RF energy transmitted by the base unit <b>200</b> thereby forming the response wireless communications. The microcontroller <b>106</b> may be implemented as a state machine designed into a programmable logic array, or may be a processor controlled via firmware. Each of these embodiments are designer choices that do not affect the novelty of the invention.

0218Similarly, the energy store <b>108</b> has been shown internal to the passive transponder <b>150</b>; however, part or all of the energy store <b>108</b> may be located off-board of the passive transponder <b>150</b> in order to provide more physical space for a larger energy store <b>108</b>. If the energy store <b>108</b> is a battery with sufficient capacity, it is possible that the passive transponder <b>150</b> does not rely upon the power radiated from the base unit <b>200</b> to periodically charge the energy store <b>108</b>. If, however, the energy store <b>108</b> is a capacitor or low capacity battery, then the passive transponder <b>150</b> may include energy management circuits such as an overvoltage clamp <b>101</b> for protection, a rectifier <b>105</b> and a regulator <b>107</b> to produce proper voltages for use by the charge pump <b>109</b> in charging the energy store <b>108</b> and powering the microcontroller <b>106</b>.

0219Low cost chipsets and related components are available from a large number of manufacturers. In the present invention, the base unit <b>200</b> to passive transponder <b>150</b> radio link budget can be designed to operate at an approximate range of up to 30 meters. In a typical installation, each opening will have a passive transponder <b>150</b> installed. The ratio of passive transponders <b>150</b> to each base unit <b>200</b> will typically be 3 to 8 in an average residential home, although the technology of the present invention has no practical limit on this ratio. The choice of addressing range is a designer's choice largely based on the desire to limit the transmission of wasted bits. In order to increase the security of the transmitted bits, the passive transponders <b>150</b> can include an encryption algorithm. The tradeoff is that this will increase the number of transmitted bits in each message. The key to be used for encryption can be exchanged during enrollment.

0220Passive transponders <b>150</b> are typically based upon a modulated backscatter design. Each passive transponder <b>150</b> in a room can absorb power radiated from one or more base units <b>200</b> when the passive transponder <b>150</b> is being addressed, as well as when other passive transponders <b>150</b> are being addressed. In addition, the base units <b>200</b> can radiate power for the purpose of providing energy for absorption by the passive transponders <b>150</b> even when the base unit <b>200</b> is not interrogating any passive transponders <b>150</b>. Therefore, unlike most RFID applications in which the passive transponders <b>150</b> or tags are mobile and in the read zone of a prior art base unit briefly, the passive transponders <b>150</b> of the present invention are fixed relative to the base units <b>200</b> and therefore always in the read zone of at least one base unit <b>200</b>. Therefore, the passive transponders <b>150</b> have extremely long periods of time in which to absorb, integrate, and store transmitted energy.

0221In a typical day to day operation, the base unit <b>200</b> is making periodic transmissions. The master controller <b>251</b> will typically sequence the transmissions from the base units <b>200</b> so as to prevent interference between the transmissions of any two base units. The master controller <b>251</b> will also control the rates and transmission lengths, depending upon various states of the system. For example, if the security network <b>400</b> is in a disarmed state during normal occupancy hours, the master controller <b>251</b> may use a lower rate of transmissions since little or no monitoring may be required. When the security network <b>400</b> is in an armed state, the rate of transmissions may be increased so as to increase the rate of wireless communications between the base units <b>200</b> and the various sensors. The increased rate of wireless communications will reduce the latency from any attempted intrusion to the detection of the attempted intrusion. The purpose of the various transmissions will generally fall into several categories including: power transfer without information content, direct addressing of a particular passive transponder <b>150</b>, addressing to a predetermined group of passive transponders <b>150</b>, general addressing to all passive transponders <b>150</b> within the read range, and radiation for motion detection.

0222A passive transponder <b>150</b> can typically only send a response wireless communication in reply to a transmission from a base unit <b>200</b>. Furthermore, the passive transponder <b>150</b> will typically only send a response wireless communication if the passive transponder <b>150</b> has information that it desires to communicate. Therefore, if the base unit <b>200</b> has made a globally addressed wireless communication to all passive transponders <b>150</b> asking if any passive transponder <b>150</b> has a change in status, a passive transponder <b>150</b> is not required to respond if in fact it has no change in status to report. This communications architecture reduces the use of resources on multiple levels. On the other hand, if an intrusion sensor <b>600</b> detects a probable intrusion attempt, it is desirable to reduce the latency required to report the probable intrusion attempt. Therefore, the communications architecture also includes a mechanism whereby a passive transponder <b>150</b> can cause an interrupt of the otherwise periodic transmissions of any category in order to request a time in which the passive transponder <b>150</b> can provide a response wireless communication with the details of the probable intrusion attempt. The interrupt might be, for example, an extended change of state of the antenna (i.e., from terminate to shorted) or a sequence of bits that otherwise does not occur in normal communications messages (i.e., 01010101). An example sequence may be: (a) the base unit <b>200</b> may be transmitting power without information content, (b) a first passive transponder <b>150</b> causes an interrupt, (c) the base unit <b>200</b> detects the interrupt and sends a globally addressed wireless communication, (d) the first passive transponder <b>150</b> sends its response wireless communications. This example sequence may also operate similarly even if in step (a) the base unit <b>200</b> had been addressing a second passive transponder; steps (b) through (d) may otherwise remain the same.

0223If the passive transponder <b>150</b> does not contain an energy store <b>108</b> with sufficient capacity, energy to power the passive transponder <b>150</b> is derived from the buildup of electrostatic charge across the antenna elements <b>110</b> of the passive transponder <b>150</b>. As the distance increases between the base unit <b>200</b> and the passive transponder <b>150</b>, the potential voltage that can develop across the antenna elements declines. For example, under 47 C.F.R. 15.245 the base unit <b>200</b> can transmit up to 7.5 W power. At a distance of 10 m, this transmitted power generates a field of 1500 mV/m and at a distance of 30 m, the field declines to 500 mV/m.

0224The passive transponder <b>150</b> may therefore include a charge pump <b>109</b> in which to incrementally add the voltages developed across several capacitors together to produce higher voltages necessary to charge the on-board and/or off-board energy store <b>108</b> and/or power the various circuits contained within the passive transponder <b>150</b>. Charge pump circuits for boosting voltage are well understood by those skilled in the art. For example, U.S. Pat. Nos. 5,300,875 and 6,275,681 contain descriptions of some circuits.

0225One embodiment of the passive transponder <b>150</b> can contain a battery <b>111</b>, such as a button battery (most familiar use is as a watch battery) or a thin film battery. Batteries of these shapes can be based upon various lithium compounds that provide very long life. Therefore, rather than relying solely on a limited energy store <b>108</b> such as a capacitor, the passive transponder <b>150</b> can be assured of always having sufficient energy through a longer life battery <b>111</b> component. In order to preserve charge in the battery <b>111</b>, the microcontroller <b>106</b> of the passive transponder <b>150</b> can place some of the circuits in the passive transponder <b>150</b> into temporary sleep mode during periods of inactivity. The use of the battery <b>111</b> in the passive transponder <b>150</b> typically does not change the use of the passive modulated backscatter techniques as the communications means. Rather, the battery <b>111</b> is typically used to enhance and assist in the powering of the various circuits in the passive transponder <b>150</b>.

0226One means by which the passive transponder <b>150</b> replies to the base unit <b>200</b> uses a modulation such as On-Off Keyed (OOK) amplitude modulation. The OOK operates by receiving a carrier wave from the base unit <b>200</b> at a center frequency selected by the base unit, or a master controller <b>251</b> directing the base unit, and modulating marking (i.e., a “one”) and spacing (i.e., a “zero”) bits onto the carrier wave at shifted frequencies. The marking and spacing bits obviously use two different shifted frequencies, and ideally the shifted frequencies are selected so that neither creates harmonics that can confuse the interpretation of the marking and spacing bits. In this example, the OOK is not purely on and off, but rather two different frequency shifts nominally interpreted in the same manner as a pure on-off might normally be interpreted. The purpose is to actively send bits rather that using the absence of modulation to represent a bit. The use of OOK, and in particular amplified OOK, makes the detection and interpretation of the return signal at the base unit <b>200</b> simpler than with some other modulation schemes.

0227In addition to the charge pump <b>109</b> for recharging the battery <b>111</b>, the passive transponder <b>150</b> may contain circuits for monitoring the charged state of the battery <b>111</b>. This state can range from fully charged to discharged in various discrete steps, and can be reported from the passive transponder <b>150</b> to the base unit <b>200</b>. For example, if the battery <b>111</b> is sufficiently charged, the passive transponder <b>150</b> can signal the base unit <b>200</b> using one or more bits in a communications message. Likewise, if the battery <b>111</b> is less than fully charged, the passive transponder <b>150</b> can signal the base unit <b>200</b> using one or more bits in a wireless communications message. Using the receipt of these messages regarding the state of the battery <b>111</b>, if present, in each passive transponder <b>150</b>, the base unit <b>200</b> can take actions to continue with the transmission of radiated power, increase the amount of power radiated (obviously while remaining within prescribed FCC limits), or even suspend the transmission of radiated power if no passive transponder <b>150</b> requires power for battery charging. By suspending unnecessary transmissions, the base unit <b>200</b> can conserve wasted power and reduce the likelihood of causing unwanted interference.

0228One form of the transponder <b>100</b>, excluding those designed to be carried by a person or animal, is typically connected to at least one intrusion sensor <b>600</b>. From a packaging standpoint, the present invention also includes the ability to combine the intrusion sensors <b>600</b> and the transponder <b>100</b> into a single package, although this is not a requirement of the invention.

0229The intrusion sensor <b>600</b> is typically used to detect the passage, or attempted passage, of an intruder through an opening in a building, such as window <b>702</b> or door <b>701</b>. Thus the intrusion sensor <b>600</b> is capable of being in at least two states, indicating the status of the window <b>702</b> or door <b>701</b> such as “open” or “closed.” Intrusion sensors <b>600</b> can also be designed under this invention to report more that two states. For example, an intrusion sensor <b>600</b> may have four states, corresponding to window <b>702</b> “closed,” window <b>702</b> “open 2 inches,” window <b>702</b> “open halfway,” and window <b>702</b> “open fully.”

0230In a typical form, the intrusion sensor <b>600</b> may simply detect the movement of a portion of a window <b>702</b> or door <b>701</b> in order to determine its current state. This may be accomplished, for example, by the use of one or more miniature magnets, which may be based upon rare earth metals, on the movable portion of the window <b>702</b> or door <b>701</b>, and the use of one or more magnetically actuated miniature reed switches on various fixed portions of the window <b>702</b> or door <b>701</b> frame.

0231Other forms are also possible. For example, pressure sensitive contacts may be used whereby the movement of the window <b>702</b> or door <b>701</b> causes or relieves the pressure on the contact, changing its state. The pressure sensitive contact may be mechanical or electromechanical such as a MEMS device. Alternately various types of Hall effect sensors may also be used to construct a multi-state intrusion sensor <b>600</b>. In any of these cases, the input/output leads of the intrusion sensor <b>600</b> are connected to, or incorporated into, the transponder <b>100</b> such that the state of the intrusion sensor <b>600</b> can be determined by and then transmitted by the transponder <b>100</b> in a message to the base unit <b>200</b>.

0232Because the transponder <b>100</b> is a powered device (without or without the battery <b>111</b>, the transponder <b>100</b> can receive and store power), and the base unit <b>200</b> makes radiated power available to any device within its read zone capable of receiving its power, other forms of intrusion sensor <b>600</b> design are also available. For example, the intrusion sensor <b>600</b> can itself be a circuit capable of limited radiation reflection. Under normally closed circumstances, the close location of this intrusion sensor <b>600</b> to the transponder <b>100</b> and the simultaneous reflection of RF energy can cause the generation of harmonics detectable by the base unit <b>200</b>. When the intrusion sensor <b>600</b> is moved due to the opening of the window <b>702</b> or door <b>701</b>, the gap between the intrusion sensor <b>600</b> and the transponder <b>100</b> will increase, thereby reducing or ceasing the generation of harmonics. Alternately, the intrusion sensor <b>600</b> can contain metal or magnetic components that act to tune the antenna <b>110</b> or frequency generating components of the transponder <b>100</b> through coupling between the antenna <b>110</b> and the metal components, or the switching in/out of capacitors or inductors in the tuning circuit. When the intrusion sensor <b>600</b> is closely located next to the transponder <b>100</b>, one form of tuning is created and detected by the base unit <b>200</b>. When the intrusion sensor <b>600</b> is moved due to the opening of the window <b>702</b> or door <b>701</b>, the gap between the intrusion sensor <b>600</b> and the transponder <b>100</b> will increase, thereby creating a different form of tuning within the transponder <b>100</b> which can also be detected by the base unit <b>200</b>. The intrusion sensor <b>600</b> can also be an RF receiver, absorbing energy from the base unit, and building an electrostatic charge upon a capacitor using a charge pump, for example. The increasing electrostatic charge will create an electric field that is small, but detectable by a circuit in the closely located transponder <b>100</b>. Again, when the intrusion sensor <b>600</b> is moved, the gap between the intrusion sensor <b>600</b> and the transponder <b>100</b> will increase, causing the transponder <b>100</b> to no longer detect the electric field created by the intrusion sensor <b>600</b>.

0233Another form of intrusion sensor <b>600</b> may be implemented with light emitting diode (LED) generators and detectors. At least two forms of LED-based intrusion sensor <b>600</b> are available. In the first form, shown in <figref idref="DRAWINGS">FIG. 25A</figref>, the LED generator <b>601</b> and detector <b>602</b> are incorporated into the fixed portion of the intrusion sensor <b>600</b> that is typically mounted on the window <b>702</b> or door <b>701</b> frame. It is immaterial to the present invention whether a designer chooses to implement the LED generator <b>601</b> and detector <b>602</b> as two separate components or a single component. Then a reflective material, typically in the form of a tape <b>603</b> can be attached to the moving portion of the window <b>702</b> or door <b>701</b>. If the LED detector <b>602</b> receives an expected reflection from the LED generator <b>601</b>, then no alarm condition is present. If the LED detector <b>602</b> receives a different reflection (such as from the paint of the window rather than the installed reflector) or no reflection from the LED generator <b>601</b>, then an intrusion is likely being attempted. The reflective tape <b>603</b> can have an interference pattern <b>604</b> embedded into the material such that the movement of the window <b>702</b> or door <b>701</b> causes the interference pattern <b>604</b> to move past the LED generator <b>601</b> and detector <b>602</b> that are incorporated into the fixed portion of the intrusion sensor <b>600</b>. In this case, the movement itself signals that an intrusion is likely being attempted without waiting further for the LED detector <b>602</b> to receive a different reflection or no reflection from the LED generator <b>601</b>. The speed of movement is not critical, as it is the data encoded into the interference pattern <b>604</b> and not the data rate that is important. The use of such an interference pattern <b>604</b> can prevent easy defeat of the LED-based intrusion sensor <b>600</b> by the simple use of tin foil, for example. A different interference pattern <b>604</b>, incorporating a different code, can be used for each separate window <b>702</b> or door <b>701</b>, whereby the code is stored into the master controller <b>251</b> and associated with each particular window <b>702</b> or door <b>701</b>. This further prevents defeat of the LED-based intrusion sensor <b>600</b> by the use of another piece of reflective material containing any other interference pattern <b>604</b>. This use of the LED-based intrusion sensor <b>600</b> is made particularly attractive by its connection with a transponder <b>100</b> containing a battery <b>111</b>. The LED generator <b>601</b> and detector <b>602</b> will, of course, consume energy in their regular use. Since the battery <b>111</b> of the transponder <b>100</b> can be recharged as discussed elsewhere, this LED-based intrusion sensor <b>600</b> receives the same benefit of long life without changing batteries.

0234A second form of LED-based intrusion sensor <b>600</b> is also available. In this form, the LED generator <b>601</b> and LED detector <b>602</b> are separated so as to provide a beam of light across an opening as shown in <figref idref="DRAWINGS">FIG. 25B</figref>. This beam of light will typically be invisible to the naked eye such that an intruder cannot easily see the presence of the beam of light. The LED detector <b>602</b> will typically be associated with the LED-based intrusion sensor <b>600</b>, and the LED generator <b>601</b> will typically be located across the opening from the LED detector <b>602</b>. In this form, the purpose of the LED-based intrusion sensor <b>600</b> is not to detect the movement of the window <b>702</b> or door <b>701</b>, but rather to detect a breakage of the beam caused by the passage of the intruder through the beam. This form is particularly attractive if a user would like to leave a window <b>702</b> open for air, but still have the window <b>702</b> protected in case an intruder attempts to enter through the window <b>702</b>. As before, it would be preferred to modulate the beam generated by the LED generator <b>601</b> so as to prevent easy defeat of the LED detector <b>602</b> by simply shining a separate light source into the LED detector <b>602</b>. Each LED generator <b>601</b> can be provided with a unique code to use for modulation of the light beam, whereby the code is stored into the master controller <b>251</b> and associated with each particular window <b>702</b> or door <b>701</b>. The LED generator <b>601</b> can be powered by a replaceable battery or can be attached to a transponder <b>100</b> containing a battery <b>111</b> so that the LED generator <b>601</b> is powered by the battery <b>111</b> of the transponder <b>100</b>, and the battery <b>111</b> is recharged as discussed elsewhere. In this latter case, the purpose of the transponder <b>100</b> associated with the LED generator <b>601</b> would not be to report intrusion, but rather only to act to absorb RF energy provided by the base unit <b>200</b> and charge the battery <b>111</b>.

0235In each of the cases, the transponder <b>100</b> is acting with a connected or associated intrusion sensor <b>600</b> to provide an indication to the base unit <b>200</b> that an intrusion has been detected. The indication can be in the form of a message from the transponder <b>100</b> to the base unit, or in the form of a changed characteristic of the transmissions from the transponder <b>100</b> such that the base unit <b>200</b> can detect the changes in the characteristics of the transmission. It is impossible to know which form of intrusion sensor <b>600</b> will become most popular with users of the inventive security network <b>400</b>, and therefore the capability for multiple forms has been incorporated into the invention. Therefore, the inventive nature of the security network <b>400</b> and the embodiments disclosed herein is not limited to any single combination of intrusion sensor <b>600</b> technique and transponder <b>100</b>.

0236In addition to the modulation scheme, the security network <b>400</b> may include an RF access protocol that contains elements of various layers of the OSI communications reference model. This invention is not specific to any chosen framing, networking, or related technique, however there are a number of characteristics of the RF access protocol that are advantageous to the invention.

0237It is preferred that base units <b>200</b> belonging to a common security network <b>400</b> are organized into a common frequency plan. Each base unit <b>200</b> described herein is a wireless transmitter. For high power RF communications, base units <b>200</b> are governed by 47 C.F.R. 15.247, which may require each base unit <b>200</b> to periodically frequency hop. It is preferred that the hopping sequences be organized in time and frequency such that no two base units <b>200</b> attempt to operate on the same frequency at the same time. Even in an average home, a security network <b>400</b> of the present invention may typically include between 4 and 10 base units <b>200</b> whose frequency management may be more complex than the few cordless phones and/or a WiFi network that may also be collocated there. 47 C.F.R. 15.247 permits some forms of frequency coordination to minimize interference and collisions, and it is preferred that any base unit <b>200</b> take advantage of those permissions.

0238Frequency coordination between the base units <b>200</b> contained in separate but nearby security networks <b>400</b> may be required. Each security network <b>400</b> will typically be operating its own network with its own frequency plan, but in preferred implementations, the security networks <b>400</b> detect and coordinate in both time and frequency. This may be accomplished in the following example manner. The base units <b>200</b> in any first security network <b>400</b> will typically have periods of time in which no transmissions are required. Rather than idle, these base units <b>200</b> may periodically scan the frequency band of interest to determine the presence of other transmitters. Some of the other transmitters will be cordless phones and WiFi wireless access points. The scanning base units <b>200</b> can note the presence and frequency location of these other devices, especially the WiFi devices that typically maintain fixed frequencies. If the scanning base units <b>200</b> note that the same devices continue to consistently occupy the same frequency locations, the first security network <b>400</b> may opt to avoid those frequency locations to avoid interference. If the scanning base units <b>200</b> discover transmitters that are base units <b>200</b> from a second security network <b>400</b>, the first security network <b>400</b> can frequency coordinate with the second security network <b>400</b>. Then, rather than avoiding certain frequency locations to avoid interference, the two systems can share common frequencies as long as any specific frequency location is not simultaneously used by the two systems.

0239In order to improve coordination between base units, whether part of the same security network <b>400</b> or separate but nearby security networks <b>400</b>, it may be advantageous for the base units <b>200</b> to synchronize their internal timing with each other. Since any chosen RF access protocol will likely organize its transmissions into bursts, operation of the systems will typically be improved if the timing between base units <b>200</b> is synchronized so that bursts are both transmitted and received at expected times. One method by which this may be accomplished is by establishing one base unit <b>200</b> as a timing master; then each other base unit <b>200</b> may derive its own internal timing by synchronizing with the timing master. This synchronization may be accomplished by the base unit <b>200</b> listening to certain bursts transmitted from the timing master and then adjusting the base unit's timing accordingly. This may be accomplished, for example, by monitoring the framing boundaries or synchronization words of transmitted frames. The base unit <b>200</b> designated as timing master may or may not be the same as the device containing the present master controller <b>251</b>.

0240If sufficient timing and frequency coordination between separate but nearby security networks <b>400</b> has been established, these separate systems may also communicate with each other by establishing periodic frequencies and times at which messages are passed between the systems. This ability to pass messages between adjacent systems enables various forms of neighborhood networking to take place as described herein.

0241The RF access protocol may establish periods of time for communications between base units <b>200</b> and periods of time for communications between base units <b>200</b> and transponders <b>100</b>. Base units <b>200</b> will typically transmit a wireless signal to the transponders at periodic intervals. During the time of these transmitted wireless signals, the passive transponders <b>150</b> may elect to backscatter modulate the transmitted wireless signals if any of the passive transponders <b>150</b> have information to communicate. The periodic intervals may change depending upon the state of the security network <b>400</b>. For example, when the security network <b>400</b> is in an armed state, the base units <b>200</b> may transmit a wireless signal to passive transponders <b>150</b> every two seconds. This means that any state change at an intrusion sensor may be communicated to the master controller <b>251</b> within two seconds. However, when the security network <b>400</b> is in a disarmed state, the base units <b>200</b> may slow down their rate of transmitting wireless signals to the passive transponders <b>150</b> to every 30 seconds, for example, in to conserve power. The actual times may vary in practice, of course.

0242The rate of scanning is one of several parameters that the base units <b>200</b> may transmit to the transponders <b>100</b>. These parameters as a group may be used by the various transponders <b>100</b> to determine their respective operation. The rate of scanning may be used by the transponders <b>100</b> to determine how often the transponders <b>100</b> should attempt to receive communications from the base units <b>200</b> as well as when and how often a transponder <b>100</b> has an opportunity to respond to a wireless communication from the base unit <b>200</b>. Transponder <b>100</b> may place some or all of its circuits to sleep during intervals of time when the transponder <b>100</b> is not expecting to receive communications nor has any data to send. As the rate of scanning changes, the length of sleep intervals may also change.

0243The RF access protocol may or may not include encryption and authentication as part of its message structure. Radio waves can propagate over significant distances, and the communications between base units <b>200</b> and with transponders <b>100</b> can be intercepted by a technically knowledgeable intruder. If the designer of a security network <b>400</b> under the present invention is concerned about the interception of communications, the messages may be encrypted. During the manufacture and/or configuration of the security network <b>400</b>, keys may be provided to the various active and passive transponders. Once the devices have the keys, and the keys are known by the controller functions, the keys may be used for authentication and/or encryption.

0244Authentication is a process that typically involves the determination of a challenge message using a predetermined method and typically involving at least one key. The challenge message is then sent from a first device to a second device. The second device typically then determines a response message using a predetermined method and typically involving both the challenge message and at least one key. The premise is that only a valid second device knows both the method and the key required to properly respond to the challenge from the first device. There are many authentication processes known by those skilled in the art, almost any of which can be applied to the present security network <b>400</b>.

0245Encryption is a related process that typically involves both a first key and a predetermined method for using the first key to encode or encrypt a message. The encrypted message is then sent from a first device to a second device. The second device can typically decrypt or decode the message using a predetermined method and typically involving a second key known to the second device. The first key and the second key may be the same, or may have some other predetermined relationship that allows one key to decrypt messages from another key. It may be advantageous for the keys to be different so that if one key is compromised, it is possible to maintain the integrity of the remainder of the system.

0246The present security network <b>400</b> may be controlled by the user via a keypad interface <b>265</b>, which may be implemented in a handheld unit <b>260</b> or tabletop unit <b>261</b> for example. However, the present security network <b>400</b> also supports a novel method for configuration primarily using voice recognition. This novel method is not necessarily specific to a security network <b>400</b> employing communication methods as disclosed herein, but may also be applied to other types of security systems such as those of the prior art.

0247Most security networks <b>400</b>, especially those that will be monitored, include a modem <b>310</b>. In the security network <b>400</b> of the present invention, the modem <b>310</b> is contained in a gateway <b>300</b>. Then, after all of the components of the security network <b>400</b> are installed in the building and the modem is connected to the telephone line <b>431</b> the following process is then used to configure the security network <b>400</b>:

02481. The user <b>712</b> (or owner or operator) uses a base unit <b>200</b> with an acoustic transducer <b>210</b> or even a telephone <b>455</b> connected to the same telephone line <b>431</b> as the modem <b>310</b> to call a remote server or remote processor <b>461</b>, which may typically be located at a emergency response agency <b>460</b>. The user interaction is depicted by arrow A in <figref idref="DRAWINGS">FIG. 19</figref>.

02492. The remote processor <b>461</b> runs a configuration program that may include voice recognition and voice response. Data may be exchanged between the configuration program on the remote processor <b>461</b> and the modem <b>310</b> using DTMF, data over voice, data under voice, or similar modulation techniques that enable voice and data to share the same telephone line <b>431</b> (data exchange is depicted by arrow B in <figref idref="DRAWINGS">FIG. 19</figref>). Furthermore, data may be exchanged between base units <b>200</b> (depicted by arrow C in <figref idref="DRAWINGS">FIG. 19</figref>) and between base units <b>200</b> and transponders <b>100</b> (depicted by arrows D in <figref idref="DRAWINGS">FIG. 19</figref>) during the configuration process.

02503. When the user has finished the configuration program, the user may hang up the telephone <b>455</b> or terminate the voice conversation on the base unit <b>200</b> with acoustic transducer <b>210</b>. However, the modem <b>310</b> attached to the same telephone line <b>431</b> may hold the telephone line <b>431</b> active.

02514. The remote processor <b>461</b> and the modem <b>310</b> may engage in a data exchange in which software, parameters, and other configuration data may be downloaded.

02525. The modem <b>310</b> releases the telephone line <b>431</b> when the download is complete.

0253There are many advantages to this configuration process:

0254The security network <b>400</b> is not burdened with the program code and data required to run a configuration program that includes voice recognition and voice response. The amount of memory required to support this program code and data can be substantial, and it is generally only required at initial setup.

0255The remote processor <b>461</b> can have more substantial processing power, and therefore execute more complex algorithms for voice recognition than a low cost microprocessor that might typically be used in a security network <b>400</b>. More complex algorithms will generally perform with better voice recognition accuracy. Additionally, the remote processor <b>461</b> can include the data to support multiple languages so that the user can interact in the language most comfortable to the user.

0256The remote processor <b>461</b> can customize the configuration program queries and responses to the exact configuration present in the security network <b>400</b>. For example, if the security network <b>400</b> contains only two transponders <b>100</b>, then the configuration program need only ask the user to identify the labels or names of the two transponders <b>100</b> rather can continuing in an endless loop that the user must manually terminate.

0257During the data exchange (arrow B), updated software can be downloaded into the security network <b>400</b>. By calling the remote processor <b>461</b> prior to using the security network <b>400</b>, the user <b>712</b> is ensured of always receiving the latest version of software, even if the security network <b>400</b> was manufactured many months before the actual purchase.

0258During the configuration program, the user <b>712</b> can be offered additional software-based features for purchase. These features may not be part of the basic security network <b>400</b>. If the user chooses to purchase the additional software-based features, this new software can be downloaded to the security network <b>400</b> during the data exchange (arrow B).

0259The remote processor <b>461</b> maintains a copy of the configuration for the security network <b>400</b> in a database in the event of catastrophic loss of data in the security network <b>400</b>. The user can retrieve the configuration from the database in the remote processor <b>461</b> whenever needed.

0260As needed or requested, the remote processor <b>461</b> can send copies of the configuration to an emergency response agency <b>460</b>. If necessary, the remote processor <b>461</b> can convert the format of the configuration data into a format compatible with the requirements of the appropriate emergency response agency <b>460</b>. These formats may vary from one agency to another, and therefore the security network <b>400</b> is not burdened with the program code necessary to support multiple formats.

0261The user <b>712</b> can create his or her own spoken labels for different zones, base units <b>200</b>, transponders <b>100</b>, or other components of the security network <b>400</b>. In the case of the inventive security network <b>400</b>, which can support voice response, these labels can be downloaded to the inventive security network <b>400</b> during the data exchange. Then, if the security network <b>400</b> needs to identify a specific zone, base unit <b>200</b>, transponder <b>100</b>, or other component, the inventive security network <b>400</b> can play back the user's <b>712</b> own spoken label via an acoustic transducer <b>210</b> in a base unit <b>200</b>.

0262It is preferable that the remote processor <b>461</b> and the security network <b>400</b> engage in an authentication and/or encryption process to protect the configuration data exchanged between the remote processor and the security network <b>400</b>. While it is unlikely that an intruder would be monitoring the telephone line <b>431</b> at the exact moment that the user <b>712</b> (or owner or operator) is configuring the security network <b>400</b> for the first time, it is possible that a technically knowledgeable intruder might attempt later to compromise the security network <b>400</b> by accessing the telephone line <b>431</b> exterior to the building. For example, one attempt at compromise might be to connect a telephone to the telephone line <b>431</b> exterior to the building, call the remote processor <b>461</b>, and attempt to reconfigure the security network <b>400</b>.

0263One means by which the security network <b>400</b> and its configuration can be protected is by storing a user identity, a password, and a key at the remote server or remote processor <b>461</b>. When a user calls the remote processor <b>461</b> for the first time, the security network <b>400</b> attached via the modem <b>310</b> to the telephone line <b>431</b> will be in a starting state with no configuration. There will also be no user record on the remote processor <b>461</b>. The user <b>712</b> will be required to initiate a user record, beginning with a user identity and password. The user identity may be the home telephone number, or any other convenient identity. The remote processor <b>461</b> may detect that the security network <b>400</b> is in a starting state, and can assign a first key to the user record and a second key to the security network <b>400</b>. The first and second keys may be the same key or may be another predetermined relationship that enables the remote processor <b>461</b> and the security network <b>400</b> to engage in an authentication process and/or an encryption process. Different types of authentication and encryption processes are known to those skilled in the art, and any acceptable process may be implemented. An example of each process has been provided herein. Instead of the remote processor <b>461</b> assigning a key to the security network <b>400</b>, it is also acceptable for the security network <b>400</b> to contain a predetermined key that is then provided to the remote processor <b>461</b> by the user or the security network <b>400</b>. It is preferable that whichever method is used for the exchange of keys between the user, security network <b>400</b>, and remote processor <b>461</b>, that the keys be provided only once over the telephone line. Keys are most useful when their values are not discovered by someone that might attempt an intrusion, and by providing the keys only once the chances of discovery by monitoring the telephone line <b>431</b> are minimized.

0264Once the remote processor <b>461</b> contains a first key associated with the user record, and the security network <b>400</b> contains a second key, any attempt to change the configuration of the security network <b>400</b> will require the use of the keys. An intruder attempting to compromise the security network <b>400</b> by accessing the telephone line <b>431</b> exterior to the building would be required to know the user identity and password in order to access the user record in the remote processor <b>461</b>, and the first key can only be used by accessing the user record.

0265The inventive security network <b>400</b> can assist the user during the configuration program by providing certain data (arrows B, C, D) to the remote processor <b>461</b> during the call while the user is interacting (arrow A) with the configuration program. The certain data may include the number of base units <b>200</b>, the transponders <b>100</b> within detection range of each base unit <b>200</b>, and the number of gateways <b>300</b> and other devices within the security network <b>400</b>. This data may be sent to the remote processor <b>461</b> while the user is interacting with the configuration program (arrow A) either by modulating the data outside of the normal audio bandwidth of a telephone call or using a modulation like DTMF tones to send the data within the audio bandwidth. In a similar manner, the remote processor <b>461</b> may send certain commands to the security network <b>400</b>. For example, it may be advantageous for the remote processor <b>461</b> to cause certain base units <b>200</b> to emit a short tone or spoken phrase to identify itself. Then the user <b>712</b> may provide an audio label to the base unit <b>200</b> that had emitted the short tone.

0266While advantageous, it is not required that the security network <b>400</b> exchange data on the same telephone line or telecommunications interface on which the user is interacting with the remote processor <b>461</b>. It is also possible for the security network <b>400</b> to connect to the remote processor <b>461</b> using one telecommunications interface, such as an Ethernet based interface, while the user is interacting with the remote processor <b>461</b> using a telephone line, for example. The remote processor <b>461</b> may authenticate the user using a password and may separately authenticate the security network <b>400</b> using an authentication key.

0267One advantageous interface mechanism available for use with the security network <b>400</b> is voice recognition and voice response. When a base unit <b>200</b> is manufactured with an acoustic transducer <b>210</b>, the base unit <b>200</b> can also include software-based functionality in the program code to interpret spoken words as commands to the security network <b>400</b>. Similarly, the security network <b>400</b> can respond to spoken word commands with spoken word responses or tones. Software to perform voice recognition and voice response is widely available and known to those skilled in the art, though most existing software must be modified to support the relative noisy environment of the typical home. U.S. Pat. No. 6,574,596, issued to Bi, et al., provides one example description of voice recognition, as do several well-known textbooks. With the voice recognition and voice response as the primary interface mechanism, it is possible to implement a version of the inventive security network <b>400</b> with no keypad <b>265</b>. The base units <b>200</b> with acoustic transducers <b>210</b> can be used by authorized users to perform various functions, including the day to day functions such as arming and disarming the system. One attractive advantage of incorporating voice recognition and voice response into the security network <b>400</b> via the acoustic transducer <b>210</b> in the base unit <b>200</b> is that the security network <b>400</b> can be armed or disarmed from any room in the house in which a base unit <b>200</b> is installed. The voice commands received at a single base unit <b>200</b> can be communicated to the controller functions <b>250</b> of all other devices in the security network <b>400</b>.

0268In addition to its support of multiple modulation schemes, the base unit <b>200</b> is available in an embodiment with multiple antennas <b>206</b> that enables the base unit <b>200</b> to subdivide the space into which the base unit <b>200</b> transmits and/or receives. It is well known in antenna design that it is desirable to control the radiation pattern of antennas to both minimize the reception of noise and maximize the reception of desired signals. An antenna that radiates equally in all directions is termed isotropic. An antenna that limits its radiation into a large donut shape can achieve a gain of 2 dBi. By limiting the radiation to the half of a sphere above a ground place, an antenna can achieve a gain a 3 dBi. By combining the two previous concepts, the gain can be further increased. By expanding upon these simple concepts to create antennas that further limit radiation patterns, various directional gains can be achieved. The base unit <b>200</b> circuit design permits the construction of embodiments with more than one antenna, whereby the transceiver circuits can be switched from one antenna to another. In one embodiment, the base unit <b>200</b> will typically be plugged into an outlet <b>720</b>. Therefore, the necessary coverage zone of the base unit <b>200</b> is logically bounded by the planes created by the floor below the reader and the wall behind the reader. Therefore, relative to an isotropic antenna, the read zone of the base unit <b>200</b> should normally be required to cover the space contained within only one-quarter of a sphere. Therefore, a single antenna configured with the base unit <b>200</b> should typically be designed for a gain of approximately 6 dBi.

0269However, it may be desirable to further subdivide this space into multiple subspaces, for example a “left” and a “right” space, with antenna lobes that overlap in the middle. Each antenna lobe may be then able to increase its design gain to approximately 9 dBi or more. Since the base units <b>200</b> and transponders are fixed, the base unit <b>200</b> can “learn” in this example “left”/“right” configuration which transponders have a higher received signal strength in each of the “left” and “right” antennas <b>206</b>. The simplest method by which this can be achieved is with two separate antennas <b>206</b>, with the transceiver circuits of the base unit <b>200</b> switching between the antennas <b>206</b> as appropriate for each transponder <b>100</b>. This enables the base unit <b>200</b> to increase its receiver sensitivity to the reflected signal returning from each transponder <b>100</b> while improving its rejection to interference originating from a particular direction. This example of two antennas <b>206</b> can be expanded to three or four antennas <b>206</b>. Each subdivision of the covered space can allow a designer to design an increase in the gain of the antenna <b>206</b> in a particular direction. Because the physical packaging of the base unit <b>200</b> has physical depth proportionally similar to its width, a three antenna <b>206</b> pattern is a logical configuration in which to offer this product, where one antenna <b>206</b> looks forward, one looks left, and the other looks right. An alternate configuration which is equally logical, can employ four antennas <b>206</b>, one antenna <b>206</b> looks forward, the second looks left, the third looks right, and the fourth looks up. These example configurations are demonstrated in <figref idref="DRAWINGS">FIGS. 22A and 22B</figref>. To aid in visual understanding, the antennas shown in <figref idref="DRAWINGS">FIGS. 22A and 22B</figref> appear to be microstrip or patch antennas, however the invention is not intended to be limited to those antenna forms. Other forms of antennas such as dipole, bent dipole, helical, etc. that are well known in the art can also be used without subtracting from the invention.

0270There are multiple manufacturing techniques available whereby the antennas can be easily printed onto circuit boards or the housing of the base unit <b>200</b>. For example, the reader is directed to Compact and Broadband Microstrip Antennas, by Kin-Lu Wong, published by Wiley, 2002, as one source for a description of the design and performance of microstrip antennas. This present specification is not recommending the choice of any one specific antenna design, because so much relies on the designer's preference and resultant manufacturing costs. However, when considering the choice for antenna design for both the base unit <b>200</b> and the transponder <b>100</b>, the following should be taken into consideration. Backscatter modulation relies in part upon the Friis transmission equation and the radar range equation. The power P_rthat the receiving base unit <b>200</b> can be expected to receive back from the transponder <b>100</b> can be estimated from the power P_ttransmitted from the transmitting base unit, the gain G_tof the transmitting base unit <b>200</b> antenna, gain G_rof the receiving base unit <b>200</b> antenna, the wavelength λ of the carrier frequency, the radar cross section a of the transponder <b>100</b> antenna, and the distances R₁from the transmitting base unit <b>200</b> to the transponder <b>100</b> and R₂from the transponder <b>100</b> to the receiving base unit <b>200</b>. (Since more than one base unit <b>200</b> can receive a wireless communication from the transponder, the general case is considered here.) The radar range equation is then: <br /><i>P</i>_r<i>=P</i>_t<i>·σ·[G</i>_t<i>·G</i>_r/4π]·[λ4<i>πR</i>₁<i>R</i>₂]²

0271Therefore, the designer should consider antenna choices for the base units <b>200</b> and transponders <b>100</b> that maximize, in particular, G_rand σ. The combination of P_tand G_tcannot result in a field strength that exceeds the prescribed FCC rules. The foregoing discussion of microstrip antennas does not preclude the designer from considering other antenna designs. For example, dipoles, folded dipoles, and log periodic antennas may also be considered. Various patents such as U.S. Pat. Nos. 6,147,606, 6,366,260, 6,388,628, 6,400,274, among others show examples of other antennas that can be considered. Unlike other applications for RFID, the security network <b>400</b> of the present invention uses RFID principles in a primarily static relationship. Furthermore, the relationship between the base unit <b>200</b> antennas and transponder <b>100</b> antennas will typically be orthogonal since most buildings and homes have a square or rectangular layout with largely flat walls. This prior knowledge of the generally static orthogonal layout should present an advantage in the design of antennas for this RFID application versus all other RFID applications.

0272In addition to performing the functions described herein within a single building or home, the security network <b>400</b> in one building can also operate in concert with an inventive security network <b>400</b> installed in one or more other buildings through a networking capability. There are two levels of networking supported by the security network <b>400</b>: local and server-based. Local networking operates using high power RF communications between security networks <b>400</b> installed in two different buildings. Because of the power levels supported during high power RF communications, the distance between the security networks <b>400</b> in the two buildings can be a mile or greater, depending upon terrain. Each of the security networks <b>400</b> remains under the control of their respective master controllers <b>251</b>, and the controller function <b>250</b>, including both the program code and configuration data, of each device remains dedicated to its own security network <b>400</b>. However, an authorized user of one security network <b>400</b> and an authorized user of a second security network <b>400</b> can configure their respective systems to permit communications between the two security networks <b>400</b>, thereby creating a network between the two systems. This network can exist between more than just two systems; for example, an entire neighborhood of homes, each with an inventive security network <b>400</b>, can permit their respective security networks <b>400</b> to network with other security networks <b>400</b> in the neighborhood.

0273When two or more security networks <b>400</b> are networked using high power RF communications, various capabilities of each security network <b>400</b> can be shared. For example, a first security network <b>400</b> in a first home <b>740</b> can access a gateway <b>300</b> associated with a second security network <b>400</b> in a second home <b>741</b> (as shown in <figref idref="DRAWINGS">FIG. 17</figref>). This may be advantageous if, for example, an intruder were to cut the phone line associated with the first home <b>740</b>, thereby rendering useless a gateway <b>300</b> containing a modem <b>310</b> installed in the first security network <b>400</b>. It is unlikely that an intruder would know to cut the phone lines associated with multiple homes. In another example, if a child wearing a transponder <b>100</b> associated with the first security network <b>400</b> is present in the second home, the second security network <b>400</b> can communicate with the transponder <b>100</b> on the child and provide the received transponder <b>100</b> data to the first security network <b>400</b>, thereby enabling a parent to locate a child at either the first home or the second home. In yet another example, if the first security network <b>400</b> in the first home <b>740</b> causes an alert the first security network <b>400</b> can request the second security network <b>400</b> to also cause an alert thereby notifying the neighbors at the second home <b>741</b> of the alert and enabling them to investigate the cause of the alert at the first home <b>740</b>. This may be useful if for example the occupants are away on travel. In yet another example, the base units <b>200</b> in a second security network <b>400</b> in a second home <b>741</b> may be within communications range of the transponders <b>100</b> in a first security network <b>400</b> in a first home <b>740</b>. The base units <b>200</b> in the second security network <b>400</b> may forward any received communications to the controller function <b>250</b> in the first security network <b>400</b>, thereby providing another form of spatial antenna diversity. This may be particularly useful for any transponders <b>100</b> located outside of the home where the first security network <b>400</b> is installed.

0274When two security networks <b>400</b> are beyond the range of communications via high power RF communications, the security networks <b>400</b> may still form a network through their respective gateways. The security networks <b>400</b> may either network through direct connection between their respective gateways <b>300</b> or may network through an intermediate remote server <b>461</b>. The use of an intermediate remote server <b>461</b> can enable the first security network <b>400</b> and the second security network <b>400</b> to have different types of communications modules (i.e., modem, Ethernet, WiFi, USB, wireless, etc.) installed in the gateway <b>300</b> of each respective security network <b>400</b>. Since a commercial emergency response agency <b>460</b> will likely already have servers <b>461</b> equipped to support the various types of communications modules installed in various gateways, the provision of an intermediate server for networking security networks <b>400</b> may present an expanded business opportunity.

0275Networking through intermediate remote servers <b>461</b> expands the applications and usefulness of the inventive security network <b>400</b>. For example, there may be a caregiver that would like to monitor an elderly parent living alone in another city. Using the networking feature, the caregiver can monitor the armed/disarmed status of the security network <b>400</b> in the home of the elderly parent, use two-way audio and/or the camera <b>213</b> of the security network <b>400</b> to check on the elderly parent, and monitor any transponder <b>100</b> worn by the elderly parent. This may be equally useful for parents to monitor a student living away at college or other similar family situations.

0276In either form of networking, the security network <b>400</b> can provide an authentication mechanism to ensure that networking is not inadvertently enabled with another unintended security network <b>400</b>. The authentication mechanism may consist of the mutual entering of an agreed security code in each of the two security networks <b>400</b> which are to network. In their communications with each other, the two security networks <b>400</b> may send and verify that the security codes properly match before permitting various operations between the two systems. Other authentication mechanisms may also be used, such as the shared use of a designated master key. In this example, rather that requiring the mutual entering of an agreed security code, each of the security networks <b>400</b> which are to network can be required to first read the same designated master key.

0277Other embodiments of transponders <b>100</b> may exist under the present invention. Two example forms of passive infrared sensors <b>570</b> can be created by combining a passive infrared sensor <b>570</b> with the circuits of the transponder <b>100</b>. As shown in <figref idref="DRAWINGS">FIG. 14A</figref>, in one embodiment the passive infrared sensor <b>570</b> with its power supply <b>207</b> is integrated into the packaging of a light switch <b>730</b>. Within this same packaging, a transponder <b>100</b> is also integrated. The passive infrared sensor <b>570</b> operates as before, sensing the presence of a warm body <b>710</b>. The output of the passive infrared sensor <b>570</b> circuits is connected to the transponder <b>100</b> whereby the transponder <b>100</b> can relay the status of the passive infrared sensor <b>570</b> (i.e., presence or no presence of a warm body <b>710</b> detected) to the base unit <b>200</b>, and then to the master controller <b>251</b>. At the time of system installation, the master controller <b>251</b> is configured by the user thereby identifying the rooms in which the base units <b>200</b> are located and the rooms in which the passive infrared sensors <b>570</b> are located. If desired, the master controller <b>251</b> can then associate each passive infrared sensor <b>570</b> with one or more base units <b>200</b> containing microwave Doppler algorithms. The master controller <b>251</b> can then require the simultaneous or near simultaneous detection of motion and a warm body <b>710</b>, such as a person, before interpreting the indications as a probable person in the room.

0278It is not a requirement that the passive infrared sensor <b>570</b> be packaged into a light switch <b>730</b> housing. As shown in <figref idref="DRAWINGS">FIG. 14B</figref>, in another embodiment the passive infrared sensor <b>570</b> is implemented into a standalone packaging. In this embodiment, both the passive infrared sensor <b>570</b> and the transponder <b>100</b> are battery powered so that this sensor/transponder <b>100</b> combination can be located anywhere within a room. So, for example, this embodiment allows the mounting of this standalone packaging on the ceiling, for a look down on the covered room, or the mounting of this standalone packaging high on a wall.

0279A single security network <b>400</b> is comprised of various embodiments of base units <b>200</b> and transponders <b>100</b> that the end-user desires to associate with each other. There may be multiple security networks <b>400</b> installed in close proximity to each other, such as within a single building, group of buildings, or neighborhood. It is therefore important that the proper base units <b>200</b> and transponders <b>100</b> become enrolled with the proper security network <b>400</b>, and not mistakenly enrolled with the wrong security network <b>400</b>. Base units <b>200</b> that are enrolled with the master controller <b>251</b> of a security network <b>400</b> may be controlled by that master controller <b>251</b>. Similarly, transponders <b>100</b> enrolled with the master controller <b>251</b> of a security network <b>400</b> will be monitored by that security network <b>400</b>. For the purposes of describing the various processes and states during configuration and enrollment, the terminology of the following paragraph shall be used.

0280The security network <b>400</b> within an end-user's residence (or similar singular premise, whether residential, commercial, or otherwise) shall be termed the home security network <b>400</b>. This example residence may be <b>740</b> in <figref idref="DRAWINGS">FIG. 17</figref>. Other security networks <b>400</b> within RF communications range of the home security network <b>400</b>, but whose components are not owned by the end-user or intended to be enrolled with the home security network <b>400</b>, are termed neighbor security networks <b>400</b>. This may be in example residence <b>741</b>. There may, of course, be multiple neighbor security networks <b>400</b> within RF communications range of the home security network <b>400</b>. Individual components of a security network <b>400</b>, such as the various embodiments of base units <b>200</b> and transponders <b>100</b>, may be in one of two states with respect to the various processes of configuration and enrollment: enrolled or not enrolled. Each security network <b>400</b> will typically have a separate network identifier, or network ID, that is unique from the network ID of all other security networks <b>400</b> within RF communications range of the security network <b>400</b>. Individual components of a home security network <b>400</b>, such as the various embodiments of base units <b>200</b> and transponders <b>100</b>, will typically each have a serial number that is unique from the serial numbers of other components in use with any neighbor security network <b>400</b> within RF communications range of the home security network <b>400</b>. The serial number for a specific component may or may not be assigned at the time of manufacture. If the serial number is not assigned at the time of manufacture, the home security network <b>400</b> for a component may assign a serial number to that component. This may typically happen, for example, at the time of enrollment. It is particularly advantageous if the serial numbers assigned to components were encoded in a manner that identified that type of component. For example, a different numeric or alphanumeric range may be assigned to each type of component.

0281When a component is first purchased and brought within RF communications range of a home security network <b>400</b>, it will typically be in a state of “not enrolled.” The component will remain in a state of not enrolled until the home security network <b>400</b> takes action to enroll that component. If the component, such as a base unit <b>200</b> or a transponder <b>100</b>, contains a power source, such as a battery, or becomes powered, such as by plugging the component into an outlet, connecting a battery, or receiving transmitted RF power, the component may begin communicating according to a predetermined algorithm. The home security network <b>400</b> may receive communications from the component, even though in the state of not enrolled, but may not manage or monitor the component. The home security network <b>400</b> may notify the end-user that a component has been detected, but that the component is in a state of not enrolled. The end-user may then decide whether to enable the home security network <b>400</b> to enroll the component with the home security network <b>400</b>.

0282Some components may be capable of storing their enrolled/not enrolled state within the component itself. Other components may not be capable of storing their enrolled/not enrolled state, and therefore the home security network <b>400</b> must store the enrolled/not enrolled state of the component. Typically, base units <b>200</b> will contain the necessary storage mechanism to store their enrolled/not enrolled state. Similarly, some transponders <b>100</b> will also contain the necessary storage mechanism to store their enrolled/not enrolled state.

0283When a home security network <b>400</b> receives communications from a component, the serial number of the component may be entered into a table, which table will typically be located in a memory <b>211</b> of the master controller <b>251</b> of the home security network <b>400</b>. If the component has a state of enrolled, then the home security network <b>400</b> will typically not be required to take any further action. If the component has a state of not enrolled, then the home security network <b>400</b> may exchange communications with neighbor security networks <b>400</b> to determine whether any of the neighbor security networks <b>400</b> have received communications from the same component, but have entered the component into their respective tables with a state of enrolled. If so, then the home security network <b>400</b> may enter the component into a table, but record the state of the component as enrolled with a neighbor security network <b>400</b>. In this manner and over time, the home security network <b>400</b> may continue to add components to a table, in each case entering each component as enrolled with the home security network <b>400</b>, enrolled with a neighbor security network <b>400</b>, or not enrolled. When the state of a component has been determined to be enrolled in a neighbor security network <b>400</b>, the home security network <b>400</b> may forward any communications received from the component to the neighbor security network <b>400</b>. In this manner, the home security network <b>400</b> may provide antenna and communications diversity for the component in ensuring that the component's communications reach the neighbor security network <b>400</b>.

0284When the home security network <b>400</b> has received communications from a component and the component is in a state of not enrolled in either the home security network <b>400</b> or in any neighbor network, the end-user may decide to enroll the component in the home security network <b>400</b>. A designer may choose any of various means, typically through a user interface, in which to enable the home security network <b>400</b> to notify the end-user of the not enrolled component, and then enable the end-user to permit the component to become enrolled in the home security network <b>400</b>. During the process of enrollment, the end-user may be permitted to associate specific components with each other or with locations on the end-user's premises. For example, a component installed in the living room of the end-user's house may be labeled within the home security system as a living room window transponder <b>100</b>.

0285For components that are capable of storing their enrolled or not enrolled state, the components may use different serial numbers in their communications when enrolled and when not enrolled. For example, when its state is not enrolled a component may use a first serial number of a first predetermined length. When the same component is in an enrolled state, the same component may use a second serial number of a second predetermined length. The second predetermined length may be shorter than the first predetermined length, and the second serial number may be an abbreviated form of the first serial number. This may enable shorter transmissions when the component is in an enrolled state. On the other hand, the second predetermined length may be longer than the first predetermined length. For example, when a component is in an enrolled state the second serial number may be a combination of the first serial number and the network ID of the home security network <b>400</b>. The presence of the network ID of the home security network <b>400</b> in the second serial number may be used in the routing of communications. For example, a neighbor security network <b>400</b> may receive communications from a component and use the second serial number to identify that the component is enrolled with the home security network <b>400</b> and may forward the communications to the home security network <b>400</b>.

0286In addition to allowing an end-user to permit a component to be enrolled in the home security network <b>400</b>, the home security network <b>400</b> may also permit the end-user to assign a label to the component. One means by which a label may be assigned to a component is by enabling the end-user to record a verbal label for the component. This verbal label may be stored in the master controller <b>251</b> or any other controller function <b>250</b>. If any base units <b>200</b> in the home security network <b>400</b> have an audio transducer <b>210</b>, then the audio labels may be played back to the end-user at an appropriate time, such as when the security network <b>400</b> signals an alarm condition.

0287If the transponder <b>100</b> has not been manufactured with a predetermined serial number, the base unit <b>200</b> can generate, using a predetermined algorithm, a serial number and, if desired, any other information necessary to engage in encrypted communications and download these values to the transponder <b>100</b>. If the transponder <b>100</b> requires a power level higher than normally available to enable the permanent programming of these downloaded values into its microcontroller <b>106</b> or memory (in whatever form such as fuses, flash memory, EEPROM, or similar), a base unit <b>200</b> can increase its transmitted RF power subsequent to the downloading. No values need be transmitted during the period of higher transmitted RF power, and therefore there is no risk of the values being intercepted outside of the close proximity of the base unit <b>200</b> and transponder <b>100</b>. After this particular exchange, the transponder <b>100</b> is enrolled, and the master controller <b>251</b> may provide some form of feedback, such as audible or visual, to the user indicating that the transponder <b>100</b> has been enrolled.

0288The base unit <b>200</b> is not limited to reading just the transponders <b>100</b> installed in the openings of the building. The base unit <b>200</b> can also read transponders <b>100</b> that may be carried by individuals <b>710</b> or animals <b>711</b>, or placed on objects of high value. By placing a transponder <b>100</b> on an animal <b>711</b>, for example, the controller function <b>250</b> can optionally ignore indications received from the motion sensors if the animal <b>711</b> is in the room where the motion was detected. By placing a transponder <b>100</b> on a child, the controller function <b>250</b> can use a gateway <b>300</b> to send a message to a parent at work when the child has arrived home or equally important, if the child was home and then leaves the home. The transponder <b>100</b> can also include a button than can be used, for example, by an elderly or invalid person to call for help in the event of a medical emergency or other panic condition. When used with a button, the transponder <b>100</b> is capable of reporting two states: one state where the transponder <b>100</b> simply registers its presence, and the second state in which the transponder <b>100</b> communicates the “button pressed” state. It can be a choice of the system user of how to interpret the pressing of the button, such as causing an alert, sending a message to a relative, or calling for medical help. Because the base units <b>200</b> will typically be distributed throughout a house, this form of panic button can provide a more reliable radio link than prior art systems with only a single centralized receiver.

0289Embodiments of base units <b>200</b> and transponders <b>100</b> may also be made into forms compatible with various vehicles, water craft, lawn and farm equipment, and similar types of valuable property. For example, one embodiment of a base unit <b>200</b> or transponder <b>100</b> may be made in an example physical embodiment of a cigarette lighter adaptor <b>436</b>, as shown in <figref idref="DRAWINGS">FIG. 26</figref>. Given the wide use of cigarette lighter adaptors for charging cell phones and powering other equipment, there are some example vehicles that have cigarette lighters that are constantly powered, even when the vehicle has been turned off. A base unit <b>200</b> or transponder <b>100</b> in the form of a cigarette lighter adaptor <b>436</b> provides an easily installed means to monitor the vehicle against the risk of theft. Of course, other forms of base units <b>200</b> and transponders <b>100</b> may also be designed that attach in other areas of vehicles, water craft, lawn and farm equipment, and similar types of property. Some forms may be permanently wired. Even if a cigarette lighter has switched power, a base unit <b>200</b> or transponder <b>100</b> in the form of a cigarette lighter adaptor <b>436</b> may still be used if the base unit <b>200</b> or transponder <b>100</b> contains a battery. The battery may be periodically recharged when the vehicle is running. Since base units <b>200</b> are capable of high power RF communications, their RF propagation range can be much farther than a transponder <b>100</b>.

0290One advantageous security network <b>400</b> that may be formed may include one base unit <b>200</b> or transponder <b>100</b> located in a vehicle and a second base unit <b>200</b> that is handheld (i.e., example embodiment <b>260</b>). Thus, the security network <b>400</b> is not permanently affixed to a building, but rather travels with the user. When a user drives to a mall, for example, a first base unit <b>200</b> may remain in the vehicle and a second base unit <b>200</b> may be carried by the user, and the two base units <b>200</b> may continue their communications. If the first base unit <b>200</b> detects an attempted intrusion, the first base unit <b>200</b> may send a communications message to the second base unit, and the second base unit <b>200</b> may cause an alert to notify the user. In addition, the first base unit <b>200</b> may include a camera <b>213</b>, as described elsewhere in this specification, and the second base unit <b>200</b> may include a display <b>266</b> on which pictures may be viewed. The first base unit <b>200</b> may periodically record and/or send pictures to the second base unit, and in particular, the first base unit <b>200</b> may record and/or send pictures during the time in which the first base unit <b>200</b> is detecting an attempted intrusion. This may enable the user to obtain a picture-based record of the activities involving the vehicle during the time when the vehicle was parked and the user was away from the vehicle.

0291A user may configure a security network <b>400</b> in the home to include a base unit <b>200</b> or transponder <b>100</b> in a vehicle when the vehicle is located within RF propagation range of a home security network <b>400</b> or neighbor security network <b>400</b>. Similarly, a user may configure a security network <b>400</b> in the home to ignore a base unit <b>200</b> or transponder <b>100</b> in a vehicle when the vehicle has traveled outside of RF propagation range of a home security network <b>400</b> or neighbor security network <b>400</b>. This configuration enables the base unit <b>200</b> or transponder <b>100</b> in the vehicle to join the home security network <b>400</b> and therefore the user can monitor the status of the vehicle when the vehicle is parked in or near to their home. The same base unit <b>200</b> or transponder <b>100</b> in the vehicle can then be used as described above to monitor the vehicle when the user has driven the vehicle to another location such as an example mall. This form of security network <b>400</b> differs significantly from present forms of vehicle security systems that only make noise locally at the vehicle when the vehicle is disturbed.

0292The inventive security network <b>400</b> provides a number of mechanisms for users and operators to interface with the security network <b>400</b>. The security network <b>400</b> may include a base unit <b>200</b> with a keypad <b>265</b> similar to a cordless phone handset <b>260</b> or cordless phone base <b>261</b> as shown in <figref idref="DRAWINGS">FIG. 4</figref> since it is a convenient means by which authorized persons can arm or disarm the system and view the status of various zones. There are a number of keypad options that can be made available for the security network <b>400</b>, derived from permutations of the following possibilities: (i) high power RF communications or backscatter modulation communications, (ii) AC powered or battery powered, and if battery powered, rechargeable, and (iii) inclusion, or not, of sufficient processing and memory capability to also support a controller function. The example handset <b>260</b> design contains the added advantage of supporting cordless phone functionality. Thus, the security network <b>400</b> design can serve a dual purpose for users—security monitoring and voice conversation—through a single network of base units <b>200</b>. The handset-shaped <b>260</b> base unit <b>200</b> with keypad will typically be battery powered, with the battery <b>208</b> being rechargeable in a manner similar to existing cordless phones. One or more other base units <b>200</b> in the security network <b>400</b> may contain gateway <b>300</b> functionality including a connection to a telephone line <b>431</b>, Ethernet <b>401</b>, WiFi <b>404</b>, or CMRS <b>402</b> network. Like all base units <b>200</b>, the handset-shaped <b>260</b> base unit <b>200</b> with keypad <b>265</b> and the base units <b>200</b> with gateway <b>300</b> functionality can support high power RF communications with each other. This high power RF communications can support voice conversation in addition to exchanging data for the operation of the security network <b>400</b>.

0293The inventive security network <b>400</b> may include a means to provide alerts without calling the attention of an intruder to base units <b>200</b>. One means by which this may be accomplished is a remote sounder <b>437</b>. A remote sounder <b>437</b> should be less expensive than a base unit <b>200</b> with an audio transducer <b>210</b> because the remote sounder <b>437</b> contains only the functionality to receive commands from a base unit <b>200</b> and to provide the desired alert characteristics such as an audio siren. On example remote sounder <b>437</b> is shown in <figref idref="DRAWINGS">FIG. 26</figref>. This remote sounder <b>437</b> has been constructed in the shape of a lamp socket, such that (i) a light bulb may be removed from a lamp socket, (ii) the remote sounder <b>437</b> is screwed into the lamp socket, and then (iii) the light bulb is screwed into the remote sounder <b>437</b>. This example remote sounder <b>437</b> contains the mechanical means to (i) fit between a light bulb and a lamp socket, (ii) pass AC power through the remote sounder, (iii) obtain AC power from the lamp socket, (iv) receive communications from base units <b>200</b> using high power or low power RF communications, and (v) cause an audio siren when commanded by the master controller <b>251</b>. If desired, the remote sounder <b>437</b> may support two-way communications such that the master controller <b>251</b> may provide positive feedback from the remote sounder <b>437</b> that a message to alert or stop alerting has been received. Alternately, if one or more base units <b>200</b> in a security network <b>400</b> contain an audio transducer <b>210</b> that can input audio, then the master controller <b>251</b> can receive feedback by commanding the one or more base units <b>200</b> to determine whether the audio siren on the remote sounder <b>437</b> is generating audio volume that can be detected by the one or more base units <b>200</b>.

0294In addition to detecting intrusion, the security network <b>400</b> can monitor the status of other environmental quantities such as fire, smoke, heat, water, gases, temperature, vibration, motion, glass breakage as well as other measurable events or items, whether environmental or not (i.e., presence, range, location) by using an appropriate sensor <b>620</b>. The list of sensor <b>620</b> possibilities is not meant to be exhaustive, and many types of sensors <b>620</b> already exist today. For each of these sensor <b>620</b> types, the security network <b>400</b> may be configured to report an alert based upon a change in the condition or quantity being measured, or by the condition or quantity reaching a particular relationship to a predetermined threshold, where the relationship can be, for example, one or more of less than, equal to, or more than (i.e., a monitored temperature is less than or equal to a predetermined threshold such as the freezing point).

0295These detection devices can be created in at least two forms, depending upon the designer's preference. In one example embodiment, an appropriate sensor <b>620</b> can be connected to a transponder <b>100</b>, in a manner similar to that by which an intrusion sensor <b>600</b> is connected to the transponder <b>100</b>. All of the previous discussion relating to the powering of an LED generator <b>601</b> by the transponder <b>100</b> applies to the powering of appropriate sensors <b>620</b> as well. This embodiment enables the creation of low cost sensors <b>620</b>, as long as the sensors <b>620</b> are within the read range of base units.

0296In a second example embodiment, these sensor devices may be independently powered, much as base units <b>200</b> and gateways <b>300</b> are independently powered. Each of these detection devices are created by combining a sensor <b>620</b> appropriate for the quantity being measured and monitored with a local power supply, a processor, and a communications means that may include high power RF or backscatter modulation communications. These sensor <b>620</b> devices may find great use in monitoring the status of unoccupied buildings, such as vacation homes. A temperature sensor may be useful in alerting a remote building owner if the heating system has failed and the building plumbing is in danger of freezing. Similarly, a flood prone building can be monitoring for rising water while otherwise unoccupied.

0297The base unit <b>200</b> is typically designed to be inexpensively manufactured since in each installed security network <b>400</b>, there may be several base units. From a physical form factor perspective, the base unit <b>200</b> of the present invention can be made in several embodiments. One embodiment particularly useful in self-installed security networks <b>400</b> is shown in <figref idref="DRAWINGS">FIG. 13</figref>, where the packaging of the base unit <b>200</b> may have the plug integrated into the package such that the base unit <b>200</b> is plugged into a standard outlet <b>720</b> without any associated extension cords, power strips, or the like.

0298From a mechanical standpoint, one embodiment of the base unit <b>200</b> may be provided with threaded screw holes on the rear of the packaging, as shown in <figref idref="DRAWINGS">FIG. 24A</figref>. If desired by the user installing the system of the present invention, holes can be drilled into a plate <b>722</b>, which may be an existing outlet cover (for example, if the user has stylized outlet covers that he wishes to preserve) whereby the holes are of the size and location that match the holes on the rear of the packaging for the base unit, for example. Alternately, the user can employ a plate in the shape of an extended outlet cover <b>721</b> shown in <figref idref="DRAWINGS">FIG. 24B</figref> which provides additional mechanical support through the use of additional screw attachment points. Then, as shown in <figref idref="DRAWINGS">FIGS. 24A and 24B</figref>, the plate <b>722</b> or cover <b>721</b> can be first attached to the rear of the base unit <b>200</b> packaging, using the screws <b>724</b> shown, and if necessary, spacers or washers. The base unit <b>200</b> can be plugged into the outlet <b>720</b>, whereby the plate <b>722</b> or cover <b>721</b> is in alignment with the sockets of the outlet <b>720</b>. Finally, an attachment screw <b>723</b> can be used to attach the plate <b>722</b> or cover <b>721</b> to the socket assembly of the outlet <b>720</b>. This combination of screws provides positive mechanical attachment whereby the base unit <b>200</b> cannot be accidentally jostled or bumped out of the outlet <b>720</b>. Furthermore, the presence of the attachment screw <b>723</b> will slow down any attempt to rapidly unplug the base unit <b>200</b>.

0299In addition to the physical embodiments described herein, various components of the security network <b>400</b> can be manufactured in other physical embodiments. For example, modern outlet boxes used for both outlets and light switches are available in sizes of 20 cubic inches or more. In fact, many modern electrical codes require the use of these larger boxes. Within an enclosure of 20 cubic inches or more, a base unit <b>200</b> can be manufactured and mounted in a form integrated with an outlet as shown in <figref idref="DRAWINGS">FIG. 23B</figref> or a light switch in a similar configuration. The installation of this integrated base unit <b>268</b> would require the removal of a current outlet, and the connection of the AC power lines to the integrated base unit/outlet. The AC power lines would power both the base unit <b>200</b> and the outlet. One or more antennas can be integrated into the body of the base unit/outlet shown or can be integrated into the cover plate typically installed over the outlet. In addition to a cleaner physical appearance, this integrated base unit/outlet would provide the same two outlet connection points as standard outlets and provide a concealed base unit <b>200</b> capability. In a similar manner, an integrated base unit/light switch can also be manufactured for mounting within an outlet box.

0300When the inventive security network <b>400</b> includes at least one gateway <b>300</b> with modem functionality, it is advantageous for the security network <b>400</b> to seize the telephone line <b>431</b> if any other telephony device <b>455</b> (other than the security network <b>400</b> itself) is using the telephone line <b>431</b> at the time that the security network <b>400</b> requires use of the telephone line <b>431</b>. Furthermore, while the security network <b>400</b> is using the telephone line <b>431</b>, it is also advantageous for the security network <b>400</b> to prevent other telephony devices <b>455</b> from attempting to use the telephone line <b>431</b>. Therefore, the security network <b>400</b> includes several means in which to seize the telephone line <b>431</b> as shown in <figref idref="DRAWINGS">FIG. 18</figref>.

0301A gateway <b>300</b> containing modem <b>310</b> functionality may include two separate RJ-11 connectors of the type commonly used by telephones, fax machines, modems, and similar telephony devices. The first of the RJ-11 connectors is designated for connection to the telephone line <b>431</b> (i.e., PSTN <b>403</b>). The second of the RJ-11 connectors is designated for connection to a local telephony device <b>455</b> such as a telephone, fax machine, modem, etc. The gateway <b>300</b> can control the connection between the first and the second RJ-11 connector. The connection may be controlled using mechanical means, such as a relay, or using silicon means such as a FET. When the security network <b>400</b> does not require use of the telephone line <b>431</b>, the gateway <b>300</b> enables signals to pass through the gateway <b>300</b> between the first and second RJ-11 connectors. When the security network <b>400</b> requires use of the telephone line <b>431</b>, the gateway <b>300</b> does not enable signals to pass through the gateway <b>300</b> between the first and second RJ-11 connectors. In a security network <b>400</b> containing multiple gateways <b>300</b> with modem <b>310</b> functionality, the security network <b>400</b> may command all gateways <b>300</b> to stop enabling signals to pass through each gateway <b>300</b> between the respective first and second RJ-11 connectors of each gateway <b>300</b>. Thus, all telephony devices <b>455</b> connected through gateways <b>300</b> to the telephone line <b>431</b> may be disconnected from the telephone line <b>431</b> by the security network <b>400</b>.

0302In a home or other building, there may be telephony devices <b>455</b> connected to the telephone line <b>431</b> that do not connect through a gateway <b>300</b>. This may be because there are simply more telephony devices <b>455</b> in the home than there are gateways <b>300</b> in the home, for example. The inventive security network <b>400</b> may therefore include telephone disconnect devices <b>435</b> that can be used by the security network <b>400</b> to disconnect a telephony device <b>455</b> from the telephone line <b>431</b> under command of the security network. One embodiment of the telephone disconnect device <b>435</b> is shown in <figref idref="DRAWINGS">FIG. 26</figref>. In this example embodiment, the telephone disconnect device <b>435</b> includes a first male RJ-11 connector and a second female RJ-11 connector. This enables the example telephone disconnect device to be easily installed between an existing RJ-11 cord and an existing RJ-11 receptacle as shown. Other embodiments are possible, such as an embodiment that includes both first and second female RJ-11 connectors. The telephone disconnect device <b>435</b> may obtain power from the telephone line <b>431</b> or may be battery powered. The telephone disconnect device <b>431</b> can control the connection between the first and the second RJ-11 connector. The connection may be controlled using mechanical means, such as a relay, or using silicon means such as a FET. When the security network <b>400</b> does not require use of the telephone line <b>431</b>, the telephone disconnect device <b>435</b> enables signals to pass through the telephone disconnect device <b>435</b> between the first and second RJ-11 connectors. When the security network <b>400</b> requires use of the telephone line <b>431</b>, the telephone disconnect device <b>435</b> does not enable signals to pass through the telephone disconnect device <b>435</b> between the first and second RJ-11 connectors. On a standard two-wire telephone line <b>431</b>, such as those commonly used for Plain Old Telephone Service (POTS), it is not necessary for the gateway <b>300</b> or the telephone disconnect device <b>435</b> to prevent signals from passing on both wires in order to seize the telephone line <b>431</b>. Typically, even if signals on only one of the wires of the two-wire telephone line are enabled or not enabled, the gateway <b>300</b> or the telephone disconnect device <b>435</b> can enable or prevent telephony devices <b>455</b> from accessing the telephone line <b>431</b>.

0303The telephone disconnect device <b>435</b> may obtain commands from the security network <b>400</b> in any of several means. For example, the telephone disconnect device <b>435</b> may contain a wireless receiver by which to receive high power or low power RF communications from any base unit <b>200</b>. In another example, the telephone disconnect device <b>435</b> may contain an audio receiver by which to receive communications from a base unit <b>200</b>. It may be desired that the telephone disconnect device <b>435</b> be individually addressable so that the security network <b>400</b> can send commands to selected telephone disconnect devices <b>435</b> without simultaneously addressing all of the telephone disconnect devices <b>435</b>. In this example, a base unit <b>200</b>, typically a gateway <b>300</b>, may send an audio signal or a sequence of audio signals over the telephone lines of the house. These audio signals may be detected by the various telephone disconnect devices <b>435</b> as commands to either enable or not enable telephony signals to pass through the telephone disconnect devices <b>435</b>. Typically, even though a telephone disconnect device <b>435</b> will not permit signals to pass between the telephone line <b>431</b> and any telephony device <b>455</b> connected to the telephone disconnect device <b>435</b>, the telephone disconnect device <b>435</b> will remain connected to the telephone line <b>431</b> and may therefore continue to receive commands put onto the telephone line <b>431</b> by a base unit <b>200</b>. In this example, the term audio tones may include frequencies that are outside of the normal hearing of a person. For example, most telephone systems are designed to support audio below approximately 4,000 Hz. However, the present invention may employ audio at higher frequencies such as 10 KHz, 20 KHz, or even higher. Since it is not necessary or even preferred for the telephone network to interpret the audio tones sent from a base unit <b>200</b> to a telephone disconnect device <b>435</b>, there may be an advantage to using audio tones at frequencies higher that those normally supported in the telephone network.

0304As illustrated in <figref idref="DRAWINGS">FIG. 27</figref>, the security network <b>400</b> of the present invention incorporates two-way (receive and transmit) active RFID transponders (i.e., tags) <b>1000</b> with associated sensors <b>1600</b> in communication with one or more RFID readers <b>1200</b>. A transponder <b>1000</b> may be connected to a separate sensor <b>1600</b>, as shown, or the sensor <b>1600</b> may be integrated with the transponder <b>1000</b> to form a single component. The present invention encompasses both configurations, collectively included under the moniker transponder <b>1000</b> in the description that follows.

0305The sensor <b>1600</b> may be a reed switch detecting the opening or closing of a door <b>701</b> or a window <b>702</b> (two states). The sensor <b>1600</b> may be a water or temperature sensor (multiple states). The sensor <b>1600</b> may be a microphone, such as a piezoelectric microphone, to detect certain predetermined sounds. One possible predetermined sound may be a siren. For example, one such sensor <b>1600</b> may be placed next to an existing smoke detector. When the smoke detector sounds, the sensor <b>1600</b> detects the high sound pressure of the smoke detector siren. The sensor <b>1600</b> may detect not only sound pressure but frequency of the siren. Regardless of the type of sensor <b>1600</b>, the sensor <b>1600</b> changes state based upon an external event.

0306The RFID reader <b>1200</b> contains two diversity (horizontal and vertical) antennas used to transmit high power communications: a first antenna <b>1202</b> and a second antenna <b>1204</b>. A receiver <b>1206</b> for receiving low power communications is typically always operating. When the RFID reader <b>1200</b> receives a message from a transponder <b>1000</b> at low power communications, the RFID reader <b>1200</b> sends at least one first response message on one of its diversity antennas <b>1202</b> and then sends a second response message on the other of its diversity antennas <b>1204</b>. The second response message may be identical to the first response message or it may be modified in some manner. Typically, most of the message content of the second response message will be the same as or similar to the message content of the first response message. This transmission of a first response message on a first diversity antenna and a second response message on a second diversity antenna increases the probability that one or more response messages will be successfully received by the transponder <b>1000</b> (due to the repetition and transmission at different polarities). The RFID reader <b>1200</b> transmits these high power communications signals at a first frequency.

0307The RFID transponder <b>1000</b> includes a microprocessor or, more generally, a processor <b>1010</b> that controls the other components of the RFID transponder <b>1000</b>. The processor <b>1010</b> detects the change in sensor state and in response to the change in sensor state enables operation of transmitter circuitry <b>1020</b>. The transmitter circuitry <b>1020</b> is coupled to a transmit antenna <b>1030</b> for transmitting signals to the RFID reader <b>1200</b> at a second frequency (different from the first frequency of the RFID reader <b>1200</b>). A receive antenna <b>1040</b> receives signals in a frequency band that includes the first frequency. At least one RF diode <b>1050</b> obtains the signal from the receive antenna <b>1040</b> and outputs a power envelope signal representing the power level of the signal obtained from the receive antenna <b>1040</b>.

0308Typically, the first frequency transmitted by the RFID reader <b>1200</b> is at least twice the second frequency transmitted by the RFID transponder <b>1000</b>. Preferably, the first frequency is within one of the following frequency bands: 902 to 928 MHz, 2400 to 2483 MHz, or 5725 to 5825 MHz. More preferably, the first frequency is about 2.45 GHz. Preferably, the second frequency is within the frequency band 300 to 450 MHz. More preferably, the second frequency is about 345 MHz.

0309When the RF diode <b>1050</b> is coupled to the receive antenna <b>1040</b>, typically a matching network, a transistor, or both a matching network and a transistor <b>1060</b> are provided in the connection path. The purpose of the matching network is to transform the complex impedance of the receive antenna <b>1040</b> to the circuitry of the RF diode <b>1050</b>. The transistor, if present, may be used to provide some gain on the receive path. The coupling between the RF diode <b>1050</b> and the receive antenna <b>1040</b> is typically not a direct connection because of benefits of a close impedance match. An amplifier <b>1070</b> is coupled to the output of the RF diode <b>1050</b> to amplify the power envelope signal from the RF diode <b>1050</b>. The transponder <b>1000</b> is preferably constructed with a printed circuit board (PCB) <b>1090</b> that typically contains components principally on one side with a battery <b>1080</b> on the opposite side. The battery <b>1080</b> is placed in such a manner that the distance between the transmit antenna <b>1030</b> and the receive antenna <b>1040</b> is maximized.

0310The processor <b>1010</b> receives the amplified power envelope signal and decodes any data that have been encoded using an on-off keyed modulation or amplitude modulation scheme applied to the signal obtained from the receive antenna <b>1040</b>. Preferably, the processor <b>1010</b> only decodes data during a predetermined time interval. More preferably, the processor <b>1010</b> transmits a message to the RFID reader <b>1200</b> and the processor <b>1010</b> only decodes data during a predetermined time interval after the time at which the processor <b>1010</b> transmits the message. Thus, the processor <b>1010</b> preferably incorporates time selectivity into the decoding process to maximize the probability of only decoding messages that are specifically intended to be received by the transponder <b>1000</b>.

0311The transponder <b>1000</b> typically uses on-off keyed modulation for both high-and low-power communications in two different frequency bands. The transponder <b>1000</b> incorporates time selectivity, decoding communications received only during intervals when communications are expected. Finally, the transponder <b>1000</b> awakens periodically and monitors changes in the background signal pattern to indicate a status change. In this context, “awakens” refers to the transition from a first state of operating in a low power or zero power state during which current drain from the battery <b>1080</b> is minimized to a second state of operating circuitry in a manner that permits the processor <b>1010</b> to either transmit communications or receive communications. Similarly, in this context, “sleep” or “sleeping” refers to the transition to a state or the state itself of operating at low power or zero power. The life of the battery <b>1080</b> is maximized by operating the transponder <b>1000</b> in a sleep state during which current drain is minimized for long periods of time and only awakening the transponder <b>1000</b> for short periods of time to transmit communications or receive communications.

0312Most existing transponders or sensors only transmit signals. Operating under FCC regulations and security industry standards (SIA, IEEE, UL), existing transponders or sensors operate at only a single frequency and lack two-way communications. But modem reliable communication requires a two-way feedback loop; absent receipt of a return confirmation signal, the transponder or sensor never knows whether a sent transmission was received. Therefore, many existing transponders or sensors transmit messages repeatedly, wasting power and shortening the life of a battery. One reason why existing transponders or sensors only incorporate transmitting circuitry is that conventional heterodyne receiver circuitry requires too much power from a small battery-based device.

0313The transponders <b>1000</b> according to the present invention are smaller than conventional transponders or sensors yet they offer two-way communication and, therefore, enhanced reliability and longer battery life. To achieve these advantages, the transponder of the present invention uses RF diodes <b>1050</b> instead of the tuners, filters, crystals, mixers, and other standard components of the conventional heterodyne receiver. In other words, the RF diode <b>1050</b> in the transponder <b>1000</b> according to the present invention is a simpler receiver architecture. Unfortunately, however, an RF diode is not very frequency selective; rather, an RF diode will detect power from signals over a wide frequency band, a characteristic that can make the detection of the desired messages difficult. Another disadvantage of an RF diode is that the receive sensitivity of an RF diode is not as good as a conventional heterodyne receiver. Therefore, to achieve two-way communications in the transponder <b>1000</b>, the invention leverages several design improvements to the simple (and relatively inexpensive) RF diode <b>1050</b> to overcome the lack of selectivity and insensitivity characteristic of diodes.

0314This result is attained by transmitting a high power signal from the RFID reader <b>1200</b> but coding the high power signal in a unique predetermined pattern, i.e., by making the envelope of the signal look different from all other signals (e.g., Bluetooth, microwave, WiFi, and the like) that may be operating in the same or nearby frequencies that are within the receive bandwidth of the RF diode <b>1050</b>. The transponders <b>1000</b> contain algorithms that may be implemented in software that are designed to detect and decode the unique predetermined patterns. In addition, the RFID reader <b>1200</b> uses high power signals during its transmissions to overcome the low receive sensitivity of the RF diode <b>1050</b>. The use of high power communications means, however, that the system cannot operate under 47 C.F.R. § 15.231 because that regulation restricts the amount of power that can be transmitted to low power communications and the permitted power of this regulation is insufficient. Most existing security systems, and the transponders and sensors of existing security systems, operate exclusively under 47 C.F.R. § 15.231.

0315The present invention uses 47 C.F.R. § 15.247 (which encompasses Bluetooth, WiFi, cordless telephones, and the like) in order to permit the RFID readers <b>1200</b> to transmit using high power communications. The transponders <b>1000</b> communicate with their associated RFID readers <b>1200</b> typically using frequencies in one or more of the following unlicensed frequency bands: 902 to 928 MHz, 2400 to 2483 MHz, and 5725 to 5825 MHz. Preferably, the 2400 to 2483 MHz band is used because many low cost components (e.g., antenna, chip, etc.) are readily available.

0316Conventional products operating at 2.4 GHz typically communicate at high data rates of 100 kilobits per second or higher. Therefore, these products typically use some form of frequency or phase modulation schemes, but these schemes require complex receivers to support these modulation schemes. All of these products using frequency modulation or phase modulation are implemented in a manner in which the transmitted signals have a constant signal amplitude. In contrast, the high power communications to the transponders <b>1000</b> of the present invention preferable use an on-off keyed or amplitude modulation so that the transmitted signal can be more readily distinguished from other conventional products operating nearby in the same frequency band. Although two-way sensors are known, the two-way communications of the transponders <b>1000</b> of the present invention are unique. The receiver in the transponder <b>1000</b> is not a conventional heterodyne receiver (a type of receiver that uses a local oscillator at a frequency deliberately offset from that of the incoming signal, the heterodyne receiver is less sensitive than a homodyne receiver, but easier to build because it eliminates the need for a phase-locked loop) which is typically rather large and costs $2.50 or more.

0317The transponders <b>1000</b> of the present invention can have small dimensions (about 1 inch square) and can be manufactured frugally (approximately $2 or less). The transponders <b>1000</b> include a receive antenna <b>1040</b> preferably operating at a frequency of 2.4 GHz (high power), one or two RF diodes <b>1050</b>, a processor <b>1010</b>, a crystal driver for the transmitter circuitry <b>1020</b> preferably operating at a frequency of 345 MHz (low power), and a transmit antenna <b>1030</b>. Other components may be included, such as one or more filters. Although the RF diodes <b>1050</b> have a wide bandwidth, the receive antenna <b>1040</b> typically operates with a narrow receive bandwidth.

0318The low power communication at a frequency of 345 MHz is preferably selected in order to permit the RFID reader <b>1200</b> to also receive signals sent from conventional (e.g., temperature, glass breakage, motion) sensors that use this frequency; therefore, the transponder <b>1000</b> of the present invention can be compatible in frequency with those conventional components and the reader <b>1200</b> of the security network <b>400</b> can receive signals from the transponders <b>1000</b> of the present invention as well as from conventional sensors. The transponder <b>1000</b> can distinguish signals of the security network <b>400</b> from the signals from outside components.

0319It is preferred that the transponder <b>1000</b> conserves power by operating in a periodic cycle. During a portion of the periodic cycle, the transponder <b>1000</b> puts some or all of its circuits in a low power or zero power state. The transponder <b>1000</b> periodically “awakens” to transmit a signal, then waits a predetermined time and then receives a signal. Typically, the transponder <b>1000</b>, not the reader <b>1200</b>, initiates a communication sequence with the RFID reader <b>1200</b>. The RFID reader <b>1200</b> detects the transmitted signal from the transponder <b>1000</b> and waits a predetermined time before transmitting any response messages. The transponder <b>1000</b> looks for a return signal or response messages from the RFID reader <b>1200</b> only during specific times (ignoring other signals that may be received at other times). In one implementation, for example, the receiver of the transponder <b>1000</b> receives and decodes signals only for a very short time, which may be about 160 milliseconds. Thus, the transponder <b>1000</b> conserves processor time and current drain on the battery <b>1080</b>, using time selectivity rather than frequency selectivity to maximize the probability of receiving response messages or return signals from the RFID reader <b>1200</b>.

0320More specifically, the transponder <b>1000</b> typically operates using a periodic cycle in which the processor <b>1010</b> (1) enables operation of the RF diode <b>1050</b> and amplifier <b>1070</b> for a first time period, and (2) places the RF diode <b>1050</b> and amplifier <b>1070</b> in a zero power or low power state for a second time period. The first time period typically occurs at a predetermined time interval after the processor <b>1010</b> enables operation of the transmitter circuitry <b>1020</b>. The transponder <b>1000</b> may further provide a periodic cycle in which the processor <b>1010</b> (3) enables operation of the transmitter circuitry <b>1020</b> for a third time period, and (4) places the transmitter circuitry <b>1020</b> in a zero power or low power state for a fourth time period. The transponder <b>1000</b> may still further provide a periodic cycle in which the processor <b>1010</b> (5) operates at a higher power level for a fifth time period, and (6) operates in a zero power or low power state for a sixth time period. The processor <b>1010</b> measures the state of the sensor <b>1600</b> during the fifth time period and, if the state of the sensor <b>1600</b> did not change over a predetermined time period, then the processor <b>1010</b> switches to a zero power or low power state.

0321A number of sleep-action modes are possible for the transponder <b>1000</b>. In one example mode, the transponder <b>1000</b> typically sleeps but periodically wakes up (e.g., once per hour), transmits a message to the RFID reader <b>1200</b>, and waits for a response message from the RFID reader <b>1200</b>. If a valid response message is received, the transponder <b>1000</b> returns to sleep mode. If no valid response message is received, however, the transponder <b>1000</b> transmits a second message. This mode repeats for a predetermined number of cycles. Eventually, either the transponder <b>1000</b> successfully receives a response message or the transponder <b>1000</b> times out to avoid continual wasting of power.

0322In another example mode, the transponder <b>1000</b> also typically sleeps. If the sensor <b>1600</b> changes state, then the transponder <b>1000</b> wakes up, transmits a message to the reader <b>1200</b>, and waits for a response message. If a valid response message is received from the RFID reader <b>1200</b>, the transponder <b>1000</b> returns to sleep mode. If no valid response message is received, however, the transponder <b>1000</b> transmits a second message. This mode repeats for a predetermined number of cycles. Eventually, either the transponder <b>1000</b> successfully receives a response message or the transponder <b>1000</b> times out to avoid continual wasting of power.

0323The transponder <b>1000</b> typically sleeps in a third example mode. The transponder <b>1000</b> periodically wakes up (e.g., for a 50 ms period every 4 seconds), enables the RF diode <b>1050</b> and amplifier <b>1070</b>, and listens for a valid page message from the RFID reader <b>1200</b>. If no valid page message is received, the transponder <b>1000</b> returns to sleep mode. If a valid page message is received, the transponder <b>1000</b> transmits a message and waits for a response message. If no valid response message is received from the reader <b>1200</b>, the transponder <b>1000</b> transmits a second message. These actions may be repeated for a predetermined number of cycles.

0324When the transponder <b>1000</b> is in a “receive” mode, it may receive response messages from multiple RFID readers <b>1200</b>. Each RFID reader <b>1200</b> that receives a low power communications message from a transponder <b>1000</b> will typically respond to that transponder <b>1000</b>. The transponder <b>1000</b> may record the identities of the RFID readers <b>1200</b> from which it received a response message. In future transmitted low power communications messages, the transponder <b>1000</b> may include the identities of the RFID readers <b>1200</b> with which it is in two-way communication. This enables the system to report wireless coverage to the controller function <b>250</b>.

0325The RFID readers <b>1200</b> typically communicate with each other using GFSK or similar constant envelope modulation at high power at a frequency such as 2.4 GHz (i.e., no on-off keyed modulation). These communications between the RFID readers <b>1200</b> and other base units will typically take place in a predetermined framing pattern with certain characteristics bursts. For example, Bluetooth has a well known published framing pattern. Some transponders <b>1000</b> may wake up periodically from their sleep to detect the high power communications. If the RFID readers <b>1200</b> are communicating normally, a transponder <b>1000</b> detects the signal energy profile and the “normal” framing pattern but does not detect on-off keyed or amplitude modulation so the transponder <b>1000</b> returns to sleep mode. If the transponder <b>1000</b> detects a different signal energy profile such as a framing pattern other than a “normal” framing pattern, it may interpret this signal energy profile as a “page message” from an RFID reader <b>1200</b>. The transponder <b>1000</b> may then transmit a message at low power communications in response to the page message in order to request a response message from the RFID reader <b>1200</b>. This enables the transponder <b>1000</b> to advantageously determine if there are any pending commands to be sent from the RFID reader <b>1200</b> to the transponder <b>1000</b>.

0326Given their several power management characteristics, the transponders <b>1000</b> offer long power supply (e.g., battery) life approaching a target of ten years or more. With a power supply such as a battery <b>1080</b> in the transponder <b>1000</b>, the reader <b>1200</b> can be designed more economically.

0327The true scope of the present invention is not limited to the presently preferred embodiments disclosed herein. As will be understood by those skilled in the art, for example, different components, such as processors or chipsets, can be chosen in the design, packaging, and manufacture of the various elements of the present invention. The discussed embodiments of the present invention have generally relied on the availability of commercial chipsets, however many of the functions disclosed herein can also be implemented by a designer using discrete circuits and components. As a further example, the base unit and transponder can operate at different frequencies than those discussed herein, or the base units can use alternate RF communications protocols. Also, certain functions which have been discussed as optional may be incorporated as part of the standard product offering if customer purchase patterns dictate certain preferred forms. Finally, this document generally references U.S. standards, customs, and FCC rules. Various parameters, such as input power or output power for example, can be adjusted to conform with international standards. Accordingly, except as they may be expressly so limited, the scope of protection of the following claims is not intended to be limited to the specific embodiments described above.