Reduced power installation and supervision of wireless security system devices

ES 2 201 403 T3

DESCRIPTION

Low power installation and monitoring of wireless security system devices. Background of the invention

The present invention relates to communication devices and protocols, such as those used in wireless alarm systems, which have multiple wireless devices in communication with a central control unit and, in particular, to alarm systems such where the transmitting elements of the systems are designed to transmit messages at different power levels, so that (i) wireless receiver devices are installed at reduced power to ensure adequate transmission / reception margin during normal operation, and (ii) wireless transmitting devices emit monitoring messages at reduced power to guarantee a transmission / reception margin. adequate reception during the emission of alarm messages.

A recent innovation in security applications is the use of two-way wireless user interface devices, which are keyboards or panic transmitters with system status indicators. These are portable devices that can be used to monitor and interrogate the security system for the status of the system. An example of such devices are products 5827BD and 5804BD available from ADEMCO, in Syosset, NY. These have the advantages of portability, if required, or, alternatively, can be mounted in a facility, thus reducing the high costs of connecting a conventional wired user interface device. Additionally, wireless remote dialers and sirens can be used to reduce connection and labor costs.

Typically, during the installation of an alarm system, a conventional central control unit is placed in an installation mode and its reception sensitivity is reduced (see US Patent No. 4,754,261). This allows the installer to check the range of transmission signals from alarm devices, i.e. window detectors, door detectors, etc. If the central control unit recognizes an alarm indicator from the alarm device at a reduced receiver sensitivity, then there will be an adequate signal margin during normal operation. That is, if the radio environment changes during normal operation due to movement of furniture, etc., the alarm signal transmitted by the alarm devices will have sufficient signal strength to be received by the central control unit in this condition. changed and adverse.

In the case where a wireless user interface device capable of receiving signals is being installed, it is usually more difficult to ensure an adequate signal margin between the central control unit transmitter and the wireless interface device. user because currently wireless user interface devices may not be designed with a keyboard option or a switch to reduce their input sensitivity. It would be advantageous, when the receiver of the central control unit enters installation mode (reduced sensitivity), at the same time putting the transmitter of the central control unit in reduced output power mode, thus obtaining an adequate signal margin both on the uplink (central control unit user interface device to receiver) as well as on the downlink (central control unit transmitter to user interface device).

It is also desirable to ensure that the wireless remote dialer and siren are installed with adequate signal range, so that if the radio environment changes during normal operation, the messages from the central control unit transmitter are strong enough. signal to be received by the wireless remote device in this changed and adverse condition.

Thus, according to a first aspect of the present invention, it is an object to provide a method for ensuring that there is an adequate signal margin between the central control unit and the wireless devices during the installation of an alarm system.

It is also an object of the first aspect of the present invention to provide an alarm system that provides means of transmission between a central control unit and a wireless device at a reduced level of transmission during installation mode and at a normal level of transmission when not. you are in installation mode.

It is also a further object of the first aspect of the present invention to provide a common mode of installation to verify the communication between the central control unit and the wireless alarm devices (window detectors, door detectors, etc.) and, at the same time, verify communication between the central control unit and the wireless devices that have reception capabilities (user interface devices, remote siren, and remote dialer).

With respect to a second aspect of the present invention, most wireless radio frequency (RF) security systems available today employ a multiplicity of transmitters in communication with a central receiver control unit. Typically, the transmitted information describes the condition of various transducers or detectors associated with each transmitter, such as smoke, motion, glass break, shock, and vibration detectors; door, window and floor switches; etc. These transmitters are designed to be inexpensive to manufacture and are typically only capable of transmitting rather than just receiving or transmitting and receiving, which would add significant cost to the design. In order to comply with certain regulations of regulatory agencies, transmitters must periodically transmit supervisory messages to the central receiving control unit in order to identify potential communication link problems from any transmitter in the alarm system as soon as possible. possible. The supervision message (as well as a normal alarm message) comprises a unique, integrated identification code, which serves to identify the source of the supervision message (or alarm message) in particular to the central receiving control unit. Typically, when a monitoring message is properly received and detected by the central receiving control unit, the identification code is made available to the rest of the system for further processing.

ES 2 201 403 T3

For Life Safety systems, where an alarm condition may mean a health or safety emergency, the RF wireless system must also comply with more stringent regulations, such as Underwriters Laboratories' UL864 regulation. This regulation requires supervisory messages to be transmitted at a reduced power level below the alarm message level (ie normal non-supervisory signals) by at least 3 dB. Equivalent means may be employed as long as the transmission of alarm messages comprises an effective power margin above the margin of the periodic transmission of supervision messages sent by each transmitter in the alarm system.

Therefore, with respect to the second aspect of the invention, it would be advantageous if the alarm system transmitted monitoring messages at a power level below the level of the alarm messages, thus ensuring that the transmission of alarm messages has a effective margin above the margin the periodic transmission of the supervision message of each transmitter in the alarm system. Such a feature would be most beneficial if it could be applied without substantial modification to existing receivers currently in commercial use.

Additional considerations may be discovered that make it difficult to implement such a concept, such as total cost and various system parameters, including message formats and protocols and message repetition. The ideal implementation would be transparent to those parameters that could very well vary from country to country or even between different manufacturers.

Therefore, with respect to the second aspect of the invention, it would be advantageous if the alarm system provided a cost-effective means of reducing the transmitted signal power of supervisory messages and also transmitted alarm messages at full power, which is independent of parameters. such as formatting, message repetition, etc. Such a system is likely to require differentiation at the transmitter between the supervisory and alarm messages prior to transmission.

Summary of the invention

Thus, the first aspect of the present invention is a method for installing an alarm system comprising the steps of initializing an installation mode in a central control unit; transmitting a message from a transmitter at a reduced power level relative to a normal operating power level; reception in a wireless device of said message at reduced power, said wireless device being relocatable with respect to said transmitter; and indication of the moment in which said message is successfully received at reduced power. Optionally, this method includes the additional steps of, when said message is not successfully received at reduced power, then relocation of said wireless device; transmitting from said transmitter a message at a reduced power level relative to a normal operating power level; reception, in the wireless device, of said message at reduced power, said wireless device being relocatable with respect to said transmitter, and indication of the instant at which said message is successfully received at reduced power.

Thus, this first aspect of the present invention is a method of ensuring that there is an adequate signal margin between the central control unit of an alarm system and its wireless devices. Wireless devices include a remote dialer, a remote siren, and optimally a user interface device such as a two-way (transmit and receive) portable keyboard. Typically, this method is employed during installation, which is initiated by manual means of input at the central control unit and / or by selecting a user input code at the user interface device. The important feature of this method is that the central transmitter is put into a reduced power mode at the start of the installation mode.

During installation mode, the installer causes the central transmitter to transmit messages at low power and checks that the devices being installed take the appropriate actions. For example, while installing a user interface, the installer would ask the central controller for status by entering user input codes at the user interface. The central transmitter would then transmit a low power status message back to the user interface, displaying the status at the time of reception. When the installer was locating wireless devices that do not display status, such as a remote siren, the installer would simulate an alarm condition by activating a manual means of entry, a sensing device, or a user interface device such as a panic button. This causes an alarm message received at a reduced power level to be transmitted from the central transmitter to the wireless device being installed, which would take appropriate action upon receipt (ie activate the siren).

When the wireless device does not indicate that it has successfully received the reduced power message, then the wireless device is relocated by the installer and a reduced power message is relayed to the wireless device. The installer continues with this procedure until the wireless device indicates that it has successfully received a reduced power message. A reduced power level of approximately 12 dB ensures that the wireless device is installed with adequate signal range for normal operation.

Furthermore, a reduced power output of the central transmitter may be coincident with a reduced sensitivity of the central receiver. Conveniently, the installer can guarantee a system signal margin, both on the uplink and on the downlink, by activating or simulating an alarm condition on an alarm device (i.e. opening a window) and verifying that the wireless devices indicate an alarm condition.

Finally, when the installation is complete, the installer activates the normal mode of operation by initiating a manual means of entry at the central control unit, or by selecting a user entry code for normal operation on a wireless user interface device or cabling. There is also a security feature that ensures that the alarm system is not left in installation mode by the installer. An installation timer, which is activated when you enter

ES 2 201 403 T3 installation mode, makes the alarm system return to normal mode after a predetermined period of time.

This first aspect of the present invention is embodied in an alarm system comprising a central control unit with a transmitter and a plurality of wireless devices with means for receiving messages from the central transmitter. The central control unit operates both in a normal mode and in an installation mode. The central transmitter provides a means for transmission at two different output power levels, with the output transmitting at a higher power level during normal operation and the output transmitting at the lower power level during an installation mode. The central transmitter transmits electromagnetically, such as by means of radio frequency (RF), received alarm messages and other status and control messages to wireless devices. The wireless devices comprise a receiving means for receiving messages from the central transmitter and an indicator means for indicating the time when the message has been successfully received. The indicating means may be an audible sound from a remote siren, the activation of a remote dialer, and / or a visual representation or an audible sound from a user interface device. The wireless device is relocatable with respect to the central transmitter, at least until permanently mounted by the installer.

This first aspect of the present invention is based on the ability to control the energy radiated by the central transmitter. The central transmitter has two different modes of operation under the control of a processor; normal power output and reduced power output. When initiating the trigger mode, the processor outputs a control signal, causing a reduced output power level of the central transmitter. This transmitter includes simple and cost-effective circuitry. Those skilled in the art will appreciate that control of the transmitter output power can be achieved in alternative ways, although the described method offers a good low cost solution.

The central control unit may comprise an installation mode switch for activating or deactivating (normal mode) the installation mode, an alarm switch for initiating transmission of a received alarm message, and a central receiver for receiving commands transmitted by a user interface device and alarm activation signals transmitted by the alarm devices. The central receiver can also provide means for reception at two different levels of input sensitivity, the input sensitivity being higher during normal operation and the input sensitivity being lower during an installation mode.

Alarm devices, such as smoke, motion, glass break, shock and vibration detectors; door, window and floor switches; etc., transmit alarm trigger signals when triggered. The central receiver receives the alarm activation signals that cause the central system controller to transmit via the central transmitter a received alarm message to the wireless devices.

A user interface device, which can be a wall-mounted (wired or wireless) or portable transceiver device, comprises4 an input means for entering state changes, state requests, and commands such as a mode command. setup or a normal mode command. The user interface device also comprises a transmitting means for transmitting the messages and commands to the central receiver. The user interface device also comprises a receiver means for receiving status messages from the central transmitter and a status output means such as an audible sound and / or a visual representation. The user interface device may also provide a means for transmitting an alarm activation signal to the central receiver.

This first aspect of the present invention provides a unique method of accomplishing the stated objectives without compromising the simplicity of wireless devices or complicating the installation process.

The second aspect of the present invention uses a method for periodically self-evaluating a communication path in wireless alarm systems, comprising timing a supervision period to provide a delay between transmissions of supervision messages, the generation of an alarm message. supervision, the generation of a transmission power control signal, comprising one of at least two states, at the end of the supervision period, and transmitting the supervision message at a reduced power level as indicated by the status of the transmit power control signal. The second aspect of the present invention also utilizes the steps of generating an alarm status message in response to receiving an alarm status signal from an alarm detector, generating the power control signal. transmission in response to receiving the alarm status signal from the alarm detector, and transmitting the alarm status message at a normal power level as indicated by the status of the transmit power control signal.

This second aspect of the present invention is carried out by means of an apparatus for periodically self-evaluating a communication path in wireless alarm systems, comprising a monitoring period timing means for timing a duration of a monitoring period that exists between transmissions of supervision messages, a means of outputting a supervision period end signal at the end of the supervision period, a message generating means for generating the supervision message and a transmit power control signal, the transmit power control signal comprising one of at least two states, and a transmitting means for transmitting the supervision message at a predetermined reduced power level in response to a first state of the transmit power control signal.

The second aspect of the present invention is also characterized by being carried out in an alarm detector transmitter for use in a wireless alarm system, comprising a supervision period timer that times a duration of a supervision period that exists between transmissions. supervision messages and outputs a supervision period end signal, a message generator that generates the supervision message

ES 2 201 403 T3 supervision and a transmission power control signal in response to the end of the supervision period signal, the transmission power control signal comprising at least two states, the message generator generating a message alarm status signal and the transmit power control signal in response to receipt of an alarm status signal from an alarm detector, a radio frequency transmitter that transmits the monitoring message at a determined reduced power level in response to the status of the transmit power control signal and transmits the alarm status message at a predetermined normal power level in response to the status transmission power control signal, the radio frequency transmitter modulating the transmission signal with the generated supervisory message and alarm status message and outputting the modulated transmission signal, an oscillator that outputs an information clock signal to synchronize the message generator already a phase detection clock signal for synchronizing the radio frequency transmitter, the data clock signal and the phase detection clock signal being substantially in phase with each other, and a phase lock loop circuit that substantially maintains the correlation between a phase of the transmission signal and a phase of the phase detection clock signal.

Thus, the second aspect of the present invention is also realized in a data communication method and system comprising a plurality of remote devices, each comprising a means for transmitting supervision messages and non-supervision messages at different power levels, and a receiver that provides a means of receiving such messages.

The second aspect of the present invention is based on the premise that the reliability and integrity of the system are improved if supervision messages are transmitted at a lower power relative to the power of the alarm transmissions. This invention provides a unique method to achieve the stated objectives without increasing the cost or complexity of the receiver and without increasing the transmission time, to provide unique formats for monitoring messages.

The first requirement of the transmitter is that it should be able to generate a certain logic level during the period of time that a supervisory message is being generated. This logic level can then be used to control analog circuits which, in turn, control the output power.

The transmitter implemented in the present invention is based on an Application Specific Integrated Circuit (ASIC), although those skilled in the art will realize that discrete component embodiments, such as those comprising a microcontroller or microprocessor, could achieve results. similar. The ASIC includes logic circuits to generate the messages to be transmitted and further includes the RF circuits required to generate a modulated RF signal ready to be transmitted. During the generation of a supervision message, the ASIC outputs a logic level on an output pin (SUPMXI) that is used to control the output power. There are several methods available to achieve this reduction in power, such as controlling the amplifier current, switching a load across the output, or switching reactive elements in tuned circuits. Those skilled in the art will realize that power control can be fully self-contained in the ASIC as well as extended to external circuits.

The transmitted signals are received and decoded and checked for the validity of the VRC, etc .; however, since supervisory messages are transmitted at a lower power, there is an effective margin from the built-in system for alarm messages.

Brief description of the drawings

Figure 1 is a block diagram of a preferred embodiment of the alarm system of the first aspect of the present invention.

Figure 2 is a block diagram of the central control unit of Figure 1.

Figure 3 is a flow chart of the treatment used by the central control unit of Figure 1.

Figure 4 is a schematic of the central transmitter of Figure 1.

Figure 5 is a block diagram of an alarm system, utilizing reduced power supervisory message transmission, of the second aspect of the present invention.

Figure 6 is a flow chart of a method employed by the alarm detector transmitter of Figure 5 to reduce the transmit power of supervisory messages.

Figures 7A and 7B are block diagrams of a transmitter of an alarm detector of the alarm system of Figure 5.

Figure 8 is a schematic representation of an alternative embodiment of an oscillatory function and modulator function of an RF amplifier of Figures 7A and 7B, which perform the transmission of reduced power supervision messages, of the second aspect of the present invention .

Figure 9 is a schematic representation of a second embodiment of the modulating function of the RF amplifier of Figure 6.

Figure 10 is a block diagram illustrating the functional blocks of an alternate embodiment of a CRC and message generator block of Figures 7A and 7B.

Detailed description of the preferred embodiment

According to the first aspect of the present invention, Figure 1 shows a typical alarm system 5 including a central control unit 10 comprising a central system controller 70, a central receiver 90, and a central transmitter 80. The alarm system 5 also comprises a plurality of alarm devices 60, which generally refer to any or all of the various types of alarm detection devices, such as glass break detectors, door opening detectors, etc. . The alarm system 5 also comprises a user interface device in the form of a wall-mounted keypad 40, which may be connected by cables to the central receiver and the central transmitter. The wall-mounted keypad 40 can also be wireless, such as an ADEMCO 5827BD, which transmits to the central transmitter and receives from the central receiver by RF transmission. Wall-mounted keypad (wired or wireless) allows user to enter selected system options5

ES 2 201 403 T3 do some specific user codes and display the status of the system through visual and audio means. The system may also include a user interface device in the form of a portable wireless keyboard 50, such as the ADEMCO 5804BD, which allows the user to activate or deactivate the alarm system 5, trigger an alarm, determine the status of the alarm system. and display status through visual and audio indicators. The alarm system 5 also includes a remote wireless siren 20 and a remote dialer 30.

As is well known in the art, during an alarm condition, the central receiver 90 receives Alarm Activation Signals from the alarm device 60 or the portable wireless keypad 50 (eg, a panic signal). The central system controller 70 then analyzes the Alarm Activation Signals and determines if an alarm condition actually exists. If in fact an alarm condition exists, the central transmitter 80 transmits an Alarm Received Message to the remote wireless siren 20, remote dialer 30, handheld wireless keypad 50 and wall mounted keypad 40.

Receiver 90 receives status requests, installation mode commands, and other commands from wall-mounted keypad 40, which is part of the invention herein. Transmitter 80 transmits alarm status messages when the receiver receives a status request. Details concerning the command and status transmission protocol between the wireless and wired devices and the central control unit are well known to one of ordinary skill in the art.

During installation, the installer usually mounts the central control unit 10 in a hidden, remote location, because it is important to limit access to an intruder and because it is quite large and unsightly. Next, install the keypad 40 mounted on the wall of the building, at the entrance. In order to prevent the components of one alarm system from communicating with the components of another alarm system (i.e. triggering the alarm in the neighboring house), a site identifier (ID) is entered in the transmission of each device. The wall mounted keypad 40 requests that a site ID be transmitted from the central control unit 10. If the cover of the central control unit 10 has been removed (a security feature that allows the site ID to be sent only during installation), the site ID is transmitted by the central control unit 10. The site ID is programmed into the EEPROM of the central control unit 10 at the factory. Along with the site ID, the wall-mounted keypad 40 receives a device address, which is necessary for communication with the central control unit 10. The messages to and from the central control unit 10 also contain this address which allows the central control unit 10 to decode the alarm system that sent the message. The details of how a device memorizes the site ID and alarm address are well known in the art and are not described here.

The installer then enters a command, such as a status request, into the wall-mounted keypad 40 and checks that the wall-mounted keypad 40 displays the status. This ensures communication between the wall mounted keyboard 40 and the central control unit 10. The installer then enters the installation command on the 40-meter keypad mounted on the wall or activates the installation mode switch S1 to indicate to the central system controller 10 that a Power Control Signal 120 should be at level 0 logical. The Power Control Signal is connected, via cables from the central system controller 70, to both the central receiver 90 and the central transmitter 80 and causes both the central receiver 90 and the central transmitter 80 to enter a reduced power installation mode. . The reduced power setup mode causes the center receiver 90 to receive signals at a power level approximately 12 dB lower than its normal level, by reducing its sensitivity, and the center transmitter 80 to transmit messages at a power level as well. approximately 12 dB lower than its normal level.

The Power Control Signal also starts a timer in the central system controller. The timer is a safety feature, which returns the alarm system to normal mode after a predetermined period of time if the installer forgets to manually return the alarm system to normal mode.

If the wall-mounted keypad 40 is wireless, the installer will recheck its communication with the central control unit 10 by entering a status request user code on the wall-mounted keypad 40, which is transmitted to the central receiver 90 . If the status request message is received by the receiver, now at low power, the central transmitter 80 will transmit a status message to the wall-mounted keypad 40, also at low power. The installer will then check whether the wall mounted keypad 40 receives and displays the status message. If not, the installer will re-locate the wall-mounted keypad 40 and recheck its communication in the same manner.

The installer then mounts a wireless device, such as a remote siren 20, outside the building (or inside, in a basement). The site ID and device address are memorized by the wireless device in the same way as the wall-mounted keypad. A convenient way to check for adequate signal margin between the central control unit 10 and the wireless device is to simulate the presence of an alarm condition and check if the wireless device takes action. To simulate the presence of an alarm condition, the installer activates switch S2 which causes the central system controller 70 to generate an alarm received message. The received alarm message is transmitted by the central transmitter 80 at reduced power to the remote siren 20. If the remote siren 20 receives the message and performs its function (ie, plays an audible tone), the installer knows that the remote siren 20 has been installed with the proper signal range. If the remote siren 20 does not perform its function, the installer will re-locate the remote siren 20 (ie move it closer) and retest it by activating the alarm switch S2. The procedure can be repeated until the siren is heard well, thus ensuring adequate signal margin during normal mode of operation. Finally, the installer will turn off the remote siren 20

ES 2 201 403 T3 using key codes on the wall mounted keypad 40.

Once the installer finds the proper position for the first wireless device, he or she goes through the entire procedure again for each wireless device, ie, remote dialer 30 and / or portable wireless keypad 50. The procedures would be the same for each wireless device except that the installer would expect different outputs. For example, the output of the remote dialer 30 would be a telephone transmission of alarm information to a security post, and the output of the portable wireless keypad 50 would also be the visual representation of an alarm code and / or the reproduction of an audible signal. alarm.

The installer then installs the alarm devices 60 and checks the entire system for operation by causing an alarm on the device 60, such as by opening a window. The alarm device 60 transmits the Alarm Activation Signal, which is received, at reduced power, by the central receiver 90. The input data from the central receiver is processed by the central system controller. The central system controller 70 sends output data 140 to the central transmitter 80. The central transmitter 80 transmits the Alarm Received Message at reduced power to the wireless devices. Finally, the wireless devices take the appropriate measures and indicate by visual and / or acoustic means that they have received an Alarm Received Message. At this point, the installer knows that there is adequate signal margin on both the uplink and the downlink.

The installer then exits the installation mode via a typed command from the wall-mounted keypad 40. The central system controller 70 places the Power Control Signal 120 at logic level 1. This causes the central receiver 90 to receive at normal power and for the central transmitter 80 to transmit at normal power. Thus, during normal operation, all messages are sent in a higher signal range than was used during installation.

Those skilled in the art will appreciate that there are many variations in the installation of an alarm system and that the one described herein could be accomplished in other ways. For example, using the alarm device 60 or the portable wireless keypad 50 to transmit an Alarm Activation Signal in order to cause the Alarm Received Message to be generated by the central system controller 70 instead of the alarm switch S2.

The importance of the present invention resides in the ability to reduce the output power of the central transmitter 80 during the installation of the alarm system to ensure that there is adequate signal margin during normal mode of operation. It will be apparent to those skilled in the art that transmitted messages can be formatted in many different ways and that the invention is not dependent on a particular format. Also, the design of the remote siren 20, remote dialer 30, portable wireless keypad 50, wall-mounted keypad 40, and alarm devices 60 are well known in the art and need not be described.

Figure 2 shows the block diagram of the central control unit 10. Transmitter 80, receiver 90, installation mode switch S1, alarm switch S2, and central system controller 70 are shown. The central system controller 70 includes a processor 200 and its supporting digital logic, which includes memory 310 (RAM and ROM), interrupt register 305, status register 220, control register 210, and data registers. . Data registers include receiver register 225 and transmitter register 230. Receiver register 225 accepts data from input data formatter 270. Input data input to input data formatter 270 comes from receiver 90. Input data formatter 270 comprises digital logic, which also supplies a Data Ready signal to receiver register 225 and interrupt register 305. The transmitter register 230 outputs its data to the output data formatter 235 which is comprised of digital logic, which supplies the output data 140 and the authorization signal 130 osc to the transmitter 80.

Interrupt register 305 receives four interrupts, data ready, install mode, alarm, and normal mode. The data ready interrupt instructs processor 200 to read input data from receiver register 225. Interrupting the install mode switch S1 signals the processor 200 to enter install mode. The interruption of the alarm switch S2 indicates to the processor 200 to output an alarm message received through the transmitter register 230. Finally, the normal mode interrupt of the Install Timer 300 signals the processor 200 to enter normal mode from the install mode.

Status register 220 includes the status of the wireless devices, the authorization alarm status, and the mode, normal or installation. Finally, control register 210 controls the input and output power level of receiver 90 and transmitter 80 via power control signal 120. This signal also initializes the setup timer 300.

The details of the operation of each specific circuit are well known to those skilled in the art and are not described.

Figure 3 shows the flow chart of the central system controller 70. At Power Reset, the processor, 200 in FIG. 2, performs a typical startup routine, such as loading the processor program, resetting the hardware, and loading the control register. This is well known to those skilled in the art. Processor 200 also transmits a status request to the wireless devices and enters a standby mode to wait for an interrupt. Upon arrival of an interrupt request, processor 200 performs an interrupt routine that includes reading the interrupt register 305. If the processor 200 determines that the interrupt came from the setup mode Switch S1, it writes to the control register 210 by changing the logic level of the Power Control signal 120 from a logic 1 to a logic 0. If the processor 200 determines that the interrupt came from the alarm switch S2, it transmits a received alarm message to the wireless devices via the transmitter register 230. If the processor 200 determines that the interrupt came from the timer, it writes to the control register 210 by changing the logic level of the Control signal 120.

ES 2 201 403 T3

Power from a logical 0 to a logical 1. Finally, if processor 200 determines that the interrupt came from the ready data interrupt, it reads the data from receiver register 225. The input data is decoded and the processor 200 determines if there should be a change in the options stored by the status register 220, if the alarm mode should be enabled or disabled, if the transmitter and receiver should be in installation mode reduced power or normal mode, or if the input data is an alarm signal. If the input data is an alarm signal, the status register 220 is read to determine if the alarm mode is enabled. If not enabled, the transmission is ignored. If enabled, processor 200 transmits an alarm received message to wireless devices via transmitter register 230. If the input data is in error, an error is stored in the status register 220 and a message is transmitted to the wireless devices. Status register 220 is also updated after any changes have been made to the alarm system, and status messages are sent to the devices. The details of each treatment step should be well known to one of ordinary skill in the art. This flow chart does not include all the procedures necessary for the total operation of an alarm system, only the procedures pertinent to the present invention.

Figure 4 shows a detailed implementation of the power control feature of the central transmitter 80. The output of the central transmitter 80, by the antenna 400, is controlled by the power amplifier Q3. A decrease in current by Q3 causes a decrease in the output transmit power. The current through Q3 is controlled by three sources: current source 440, data signal 430, and RF signal 410. The current source 440, which is equal to the current through R1, is controlled by the Power Control signal 120. When the Power Control signal 120 is at logic 1 level, R2 is active and the current through R1 is increased. When the Power Control signal 120 is at a logic 0 level, R2 is switched out of the circuit via T1 and the current through R1 is reduced.

Data signal 430 modulates Q3 according to the logic level of Data Output signal 140, and RF signal 410 is amplified by Q3. The RF comes from the RF oscillator 420, which is enabled by the Osc Authorization signal 130. RF modulation of data signals and electrical components in this circuit is well known to one of ordinary skill in the art.

According to a second aspect of the invention, figure 5 illustrates a block diagram of an alarm system 11 comprising a central receiver control unit 12, a plurality of alarm detector transmitters 14 and a console 16. The unit 12 The central receiver control panel is in communication with the plurality of alarm detector transmitters 14, each of which comprises an alarm detector and a transmitter. Alarm detector transmitters 14 are well known in the art and comprise, for example, motion detectors, fire or smoke detectors, glass break detectors, door or window entry detectors, and the like. In the preferred embodiment, the alarm system 11 operates in a wireless manner by transmitting electromagnetic waves (eg, radio frequency waves) between the alarm detector transmitters 14 and the central receiver control unit 12. The transmitters in each alarm detector transmitter 14 are also well known in the art, and transmitted alarm and supervisory messages modulate a radio frequency signal (eg, 345 MHz). The modulated radio frequency signal is received, processed and decoded by the control unit 12 of the central receiver, enabling access to the control unit 12 of the central receiver, to provide with the information contained in the supervision or alarm message appropriately (for example, by sounding an alarm speaker, calling the police station or fire station, etc.). Additional details about wireless alarm systems can be found in U.S. Patent No. 4,754,261, issued to Marino, which belongs to the Applicant of the present invention and which is incorporated herein by reference.

The alarm detector transmitters 14 are designed to transmit supervisory and alarm messages that indicate the status of the alarm detectors according to protocols well known in the art. The supervisory message functions to provide a periodic and continuous Built-In Test (BIT) capability, ensuring that communication between each alarm detector transmitter 14 and the central receiver control unit 12 is operational. Since it is possible in this type of system that an alarm detector transmitter 14 can only transmit an alarm signal during a health or safety emergency (for example, when a window associated with the detector is broken), it is essential that the alarm system 11 maintains a periodic method to ensure that the communication link between each of the alarm detector transmitters 14 and the central receiver control unit 12 is operational, so that potential problems can be taken care of immediately during non-critical times.

Figure 6 illustrates a method used by alarm detector transmitters 14 to determine when to reduce transmitted power (ie, upon completion of a supervisory signal). At the end of the supervision period (defined later) in step 18, a supervision period end signal will be generated which, in turn, will lead to the generation of the supervision message in step 21. Simultaneously, a transmit power control signal is set to the high state (ie logic 1) indicating that the supervisory message should be transmitted at a reduced power level. However, if the supervision period has not yet ended and there has been a change in the state of one or more alarm detector transmitters 14 (i.e., a non-supervisory condition) in step 22, then a message will be generated. no supervision (an alarm message) in step 24, and the transmit power control signal will go low (logic 0). Naturally, the direction of the transmit power control signal is arbitrary as long as it is defined in advance, and consequently the intended tasks take place in response to a given direction. Just prior to transmission, the transmitter will examine the transmit power control signal at decision 26 and, if high (indicating that the message is a message

ES 2 201 403 T3 supervision), the transmitter will then transmit the message at a predetermined level of reduced power in step 28. However, if the transmit power control signal is low (indicating that the message is a non-supervisory message) then the transmitter will transmit the message at a predetermined normal or maximum level in step

31.

Figures 7A and 7B illustrate detailed upper level block diagrams of some of the essential functions of the alarm detector transmitter 14, comprising a monitoring period timer function 32, a swing function 34, a function 36 message generator, a phase lock loop function 38, a radio frequency amplifier (RF) modulator function 41, and a DC power control 42. The monitoring period timer 32 comprises an oscillator and wake-up counter 44 that operates constantly and counts the passage of time. Whenever a period of time corresponding to the supervision period has elapsed, the wake-up oscillator and counter 44 will then output a supervision period end signal 46 to the message generating function 36. The length of time corresponding to the monitoring period is set by a time constant 48 which may comprise a circuit comprising resistors and capacitors, a crystal, a resonator, or other alternative components well known in the art. Typically, the length of the supervision period is on the order of one hour or less according to applicable national regulations.

When the message generation function 36 receives the supervision period end signal, the supervision message is synthesized from a unique identification word 48, stored in non-volatile memory, a Cyclic Redundancy Verification (VRC ) and a status byte formed by several external status inputs comprising alarm detector inputs 51. Unique identification word 48 identifies the source of the supervision message as coming from a particular alarm detector transmitter 14. The VRC sequence is provided for error detection and is well known in the art (eg, see W. Stallings Data and Computer Communications 101-110 (1985), incorporated herein by reference). Additionally, since the monitoring message is being transmitted, the transmit power control signal 52 transitions to a high state, which is then used to control the transmit power set by the modulator function 41 of the RF amplifier. Conversely, if a non-supervisory message is being generated in response to a change in state of one or more alarm detector inputs 51, then the transmit power control signal 52 would hold or transition until a low state, which will cause the modulating function 41 of the RF amplifier to transmit the unsupervised message at the predetermined normal or maximum power level.

Before outputting the generated message, the message generating function 36 will enable the phase lock loop function 38 using an ENABLE BSF signal 54. Conceptually, phase lock loop circuits use feedback to maintain an output signal in a specific phase relationship with a reference signal. Here, the phase lock loop function 38 serves to maintain the phase difference between the wobble function 34 and the signal that is modulated by the message data signal 76. Typically, the modulated signal of the VCO output signal 71 is between 417 MHz and 433 MHz. The phase lock loop function 38 is comprised of a voltage controlled oscillator (VCO) 58, a loop filter 61, a phase detector 62 and a divider 64. Phase detector 62 comprises a device that produces an output voltage proportional to the phase difference between a phase detection clock 66 and an output divider signal 68. The VCO 58 is a circuit that produces an output signal 71 VCO whose frequency is proportional to the voltage of the loop filter at node A. Divider 64 is a device that produces an output divider signal 68 whose frequency is an integer division of the 71 VCO output signal. The loop filter 72 is a circuit that is used to shape the overall response of the phase lock loop function 38. The loop filter illustrated in Figures 3 and 3B is an active loop filter comprising an operational amplifier PA1 and additional discrete resistors and capacitors. When the phase lock loop 38 is synchronized, it outputs an ENABLE DATA signal 74 to the message generator function 36, allowing transmission of the generated message or message data signal 76 to the amplifier modulator function 41. RF.

The modulating function 41 of the RF amplifier modulates the output signal 71 VCO with the message data signal 76 and outputs the resulting modulated signal to an antenna. In the embodiment illustrated in Figures 3A and 3B, it is envisaged that all or nothing manipulation is used, which essentially varies the amplitude of the carrier between zero and a predetermined amplitude in response to a message data signal 76. However, alternative modulation methods, such as Phase Shift Keying and Frequency Shift Keying, could be employed while still remaining within the scope of the present invention.

The oscillation function 34 provides a data clock to the message generating function 36 by means of a data clock buffer 78 and a crystal oscillator 84 that is used in a general system clock as well as for chain synchronization. output data in message data signal 76. The oscillation function 34 also provides the phase detection clock 66 to the phase lock loop function 38 after a phase divider function 81 controlled by a frequency division control signal 82 of the message generating function 36. The oscillator output reference clock is used as the phase reference on which the phase lock loop function 38 bases the phase of its 71 VCO output signal.

The DC supply control 42 comprises an ignition reset function 84 and a battery monitor function 86. The ignition reset function 84 provides a stable reset signal to the message generating function 36 to allow orderly initialization of registers, clocks, and voltage levels when applying

ES 2 201 403 T3 energizes various circuits of the alarm detector transmitter 14. The battery monitor function 86 ensures that the voltage of a battery used as the primary power source meets the operating specifications, and if not, informs the message generating function 36 of that fact via the status portion of the battery. message or equivalent medium well known in the art.

Figure 8 illustrates an alternative embodiment of the oscillation function 34 and modulator function 41 of the RF amplifier. The transmit power control signal 52 is used to switch a resistor R21 into or out of the circuit. The switching of resistor R1 to the circuit works to increase the current through a current source defined by transistors Q1 and Q2. Q1 and Q2 work to hold approximately 0.6 V across resistor R1, and thus the value of control resistor R21 determines the current through the modulating function 88 of the RF amplifier. Transistors Q1 and Q2 function as a regulator, since the power amplifier defined by transistor Q3, resistors R22 and R23, as well as antenna 89, have a constant DC load. Thus, when resistor R1 is switched into or out of the circuit, the voltage across the power amplifier increases or decreases at various output powers. The oscillation function 34 supplies an RF signal 91 (similar to the output signal 71 VCO of Figures 7A and 7B) that is enabled by an oscillator enable signal 92 and modulated by the message data signal 76 in a substantially substantial manner. similar to that described with respect to Figures 7A and 7B. Thus, by varying the transmit power control signal 52, alarm (non-supervisory) messages can be transmitted, received and processed at full system power and all supervision messages are subjected to a reduction in radiated power. effective range of the transmitter, thus ensuring an adequate system margin.

Figure 9 illustrates a schematic representation of a second embodiment of the modulating function of the RF amplifier of Figure 6. Individual components have been annotated with information concerning part numbers and values, in addition to reference designations. In this embodiment, the transmit power control signal 52 is used to control the output power by alternately turning on and off transistors Q13 and Q17. In order to achieve low power transmission during supervision messages, Q13 and Q17 will be disconnected by circuits well known in the art contained in an output power control block.

Figure 10 illustrates a functional, hierarchical block diagram of an alternate embodiment of CRC and message generator block 36 of Figures 7A and 7B. Each of the blocks represents additional circuits (not shown) that carry out the particular functions of that block. These additional circuits would normally take the form of discrete analog and digital components, primitives in an ASIC or equivalent means well known in the art. An EDG block 94 is in charge of assembling status bits in order to construct the alarm status message. A SUPTIM block 96 monitors the output of the timer 32 of the supervision period shown in Figures 7A and 7B. A TETCLK block 98 provides clock, synchronization and control signals to the VRC and message generator. A PREAMB block 100 assembles the preamble of the various supervisory and non-supervisory messages generated by the VRC and message generator. A MAINREG block 102 provides the unique identification word of each alarm detector transmitter and embedded in the supervision message. A VRC block 104 provides error checking on messages.

The method of the present invention is not dependent for its success on sending multiple alarm or supervisory messages for each alarm event, nor is this method adversely affected by multiple transmissions. Additionally, this method does not require a specific supervisory bit in the transmitted data. The embodiment described with reference to Figure 6 may be realized in an Application Specific Integrated Circuit (ASIC) containing each of the functions illustrated in Figure 6. Those skilled in the art will realize that the present invention could also be implemented employing circuits. discrete with disadvantages in the associated cost and in the total surface of the circuit.

Thus, while particular embodiments of the present invention have been shown and described, various modifications will be apparent to those skilled in the art and, therefore, the invention is not intended to be limited to the described embodiment or details thereof, and Changes may be made to it within the scope of the present claims.