Article tracking system

Description: TECHNICAL FIELD [Detailed description of the invention]

Goods tracking system Background of the invention The present invention relates to radio frequency identification (RFID) systems in more detail. RF designed to keep track of people as they move through the building Regarding the ID system. RFID products typically have three components: (1) Tags (identified Aite) , (29 Calling device (device that detects the presence of the tag), and (3) System Useful solutions for cables (typically cables, computers, and tags and calling devices) Includes software that leads to decisions). RFID products typically have no tags Inspect tags as they pass within the effective range of some fixed or portable calling devices It is designed to be put out. RFID system is deployed as the most advanced alternative to barcode method Has been done. RFID and its related systems are passive RFID systems, capable Dynamic RFID system, infrared ID system, and electronic article monitoring (EAS) system Includes stem. Passive RFID system tags do not hold on-board power. Such a shi The stem calling device transmits the operating power for the tag. Such a system Although a slightly longer effective range is achieved, the detection range is generally within 1 meter. Has a fence. Typically, these systems have a radio frequency band of 125 kHz. Works with. Most passive RFID systems work as follows: Power the tag The calling device radiates an electromagnetic field for the purpose of doing so. The coil inside the tag is due to an electromagnetic field Powered to "wake up" the tag's circuit. The tag uses this power The identification signal is called back to the device. Although most passive RFID systems are read-only (ie, as such) System tags read information from their memory and call for that information. Answer questions by replying to the device), some passive RFID systems The tag used in is called Ability to receive information and instructions from hanging devices, eg, in industrial applications Smart card (electronic money) and electronic man Ifest) has limited reading / writing ability. Passive RFID tags include access control, smart cards, and vehicle identification ( AVI), waste management, item tracking, animal identification, production management, material management, And has been used in the context of various other purposes. One basic design goal of any RFID system is sent from the tag It makes it possible to distinguish the weak signal that is transmitted from the much stronger signal transmitted from the calling device. Is Rukoto. Some strategies to achieve this include: Frequency shift. The circuit inside the tag receives the carrier from the calling device and its signal Converts the number to another frequency and sends a modulated response on that second frequency. Half-duplex processing. Charge the tag with the calling device. The charging circuit of the calling device When turned off, the tag responds using the stored power. Modulated backscatter. The tag modulates the cross section of its antenna and calls itself to the device. Make them identify. Delayed retransmission. A surface acoustic wave (SAW) device of a calling device after a delay Resend the carrier. The tag identity is indicated by the time change during the delayed response. Active RFID systems require battery-powered tags .. Batteries allow a longer detection range, ranging from 3 to 100 meters To do. These systems have higher tag positioning than passive RFID systems. Detectable, typically frequencies at 400, 900, or 2440 MHz Operates in several bands. The active tag is a "handshake" between the tag and the calling device. Allows multiple tags to be within the effective range of the calling device As a result, each tag sends its own signal alternately. Active RFID Communication between tags and calling devices in the system is also typically passive. Faster than communication with Gu. Most active RFID tags follow the communication protocol when called Respond to the calling device. Some active RFID tags have a given time interval Spontaneously signal Chirp (send). The tag's chirp signal is called by the tag If it is within the effective range of the device, it will be detected by the calling device. Not an RFID system, but an infrared (IRID) system is also a mobile tag Attempts to detect and locate the location. A typical IRID system is randomized It has a tag that chirps its own identity at the intervals. Infrared placed on the ceiling The line reader detects these transmissions and reports them to the host. From tag to reader The transmission rate to is typically around 600 baud. Movement inspection inside the tag The output device allows the tag to be sent more frequently while it is on the move. Tags are typical It is about the size of a domino. EAS systems are intended to prevent theft in retail environments To. EAS tags are fairly unreliable, very low cost and capable Is restricted. They track moving tags, but EAS tags are coded They are generally RFID products because they are not and cannot be distinguished from each other. Is not considered to be. Outline of the invention A system that tracks movable tags has multiple antenna modules. It is equipped with a controller, which produces the carrier signal received by the tag. The tag responds by sending an identification code at random intervals, and that code Is modulated into a carrier signal. For example, an antenna module placed on the ceiling It receives the responses and sends them to the cell controller, which then sends them to the cell controller. And use them to calculate tag positions by proximity and triangulation techniques .. The distance of the tag from a particular antenna module is to measure the round trip signal time Is calculated by. The cell controller uses the processing data obtained from the received signal as the host controller. Send to computer. The host computer collects data and analyzes them To obtain the position estimate. The host computer sends the data to the data such as SQL server Store in the warehouse. One or more of the advantages of the present invention are as follows. One advantage of the present invention is to maintain tag and communication at all times while completely covering the facility. It is designed to be. The system has a terrible multipath effect Even below The position of the ginger can be specified and calculated. Another advantage of the present invention is that it uses tags with low current consumption requirements and is powered. Allows the life of the tag to approach the life of the tag's battery itself. further , The tag can enter low power mode when not in use, thereby further power saving About. Another advantage of the present invention is that it is adjustable. Widely spaced Roughly locate tags within the facility using a small number of placed antenna modules can do. Additional antenna modules in the system if more accurate tag location is desired Can be easily added. In addition, it does not require system rebuilding You can also add new tags to your system. Another advantage of the present invention is that it alleviates the problems caused by tag signal collisions. Is. Tags wake up instantly and "chirp" on a random basis, so multiple Tags can send signals at the same time. Moreover, in some situations, the system Can predict when a tag signal collision will occur and respond accordingly. Another advantage of the present invention is that the tag can respond to multiple cell controllers at the same time. Is. Other forms and advantages of the present invention will be clarified by the following statements and claims. There will be. A brief description of the drawing FIG. 1 shows an outline of a system configured according to the present invention. Figure 2 shows some cell controllers deployed in a high-rise building. FIG. 3 is a block diagram of a tag RF design according to the present invention. FIG. 4 is a block diagram of an alternative embodiment of the tag. Figure 5A-5G is a diagram of the signal as it passes through the various stages of the system. FIG. 6 is a block diagram of the RF design of the cell controller. FIG. 7 is a block diagram of the active antenna module of the cell controller. FIG. 8 is a block diagram of the RF design of the modulator. FIG. 9 is a block diagram of the cell controller cable extension module. FIG. 10 is a block diagram of the cell controller. FIG. 11 shows the extraction of tag data from a series of correlations. Figure 12A-C is a diagram of the tag datagram. FIG. 13 shows a tag having a delay element. FIG. 14 shows several cell controller reception chains operating in parallel. Detailed description of preferred embodiments With reference to Figure 1, the article tracking system 100 includes the following general elements: Tags: Low cost small radio frequency response tag 100a-c, but people tracking and / Or attached to an item. Tags 101a-c periodically wake up "Chirp" (send) a unique radio-coded identity code (UID) To do. Tags 101a-c have their scope 15 in a typical indoor environment Designed to be ~ 30 meters, the range is usually the battery life of the tag Need not to waste, as well as tag 101a and tag battery Is limited by the demand for small size and thinness. Cell controller: The cell controller 102a-c is the tag 101a-c. An active antenna that detects the jar and is connected to the cell controller 102a-c. Calculate the distance of those tags 101a-c to Joule 104a-d. Prefer Alternatively, each antenna module has a transmitting antenna and a receiving antenna. In Figure 1 And the antenna module connected to the cell controllers 102b and 102c Is omitted for simplicity. The cell controller 102a is typically in the case It is stored in and placed behind the suspended ceiling. Cell controller 102a is conventional Receives power from a wall outlet or its equivalent. Cell controller 1 02a is connected to the antenna module 104a-d through the coaxial cable 103a-d. Each is installed, and the antenna module 104a-d is in the area of indoor facility 110. Provides the effective range of the region. The tag signal 107 transmitted by the tag 101a is 1 Received by the above antenna module 104a-d and digital signal processing (D It is processed by a chip in the cell controller 102a such as the SP) chip. This The information obtained by the processing of is the identity of the transmission tag 101a, and the tag and the tag, for example. Used to identify both distances between each receiving antenna module 104a-d Used. Host computer: Cell controller 102a-c is host computer 1 Data communication with 05, the host computer 105 is the cell controller 102 Collect data and information obtained from ac, and use that data as SQL server, etc. Store in an open format database. User Application: Client War, in the preferred option Cstation 120a-c is a host through networks such as LAN115. Communicate with computer 105. Runs on each client workstation Client application 120a-c accesses the SQL server And provide data in a way that is beneficial to the end user. Tag 101a does not generate its own radio signal. Rather, the antenna module, For example, the antenna module 104a has a first frequency, eg 2440 megahel. The series spectrum spread call signal 106 is continuously transmitted. Tag 10 1a receives this signal 106 and modulates its UID code to signal 106, eg For example, at 5780 MHz, for example, a frequency shift signal 107 to the antenna 104a Reply immediately. Next, the cell controller 102a is wired and electronic. Depending on the round-trip time of transmission, the antenna mods, taking into account fixed and known delays in the Determine the distance from the tool 104a to the tag 101a. Cell controller 10 2a quickly switches between antenna modules 104a and d from tag 101a (Receive reply signal 107) Distance to each antenna module 104a-d It is possible to obtain it, and the position of the tag is determined by the triangulation method from that information. To do. System 100 is designed to be scale abl and existing cell controller Addition of cell controller to 102a-c and existing antenna module 10 It is possible to add an antenna module to 4a-d and improve the accuracy of determining the tag position. Improve. Figure 2 shows the cell controller 102a- in a large skyscraper 110. Shows how to expand the set of c. Multiple cell controllers 1 as shown in Figure 2. 02a-c typically singles data over a TCP / IP communication network Supply to the host computer 105 of. Using TCP / IP is system behavior Not required to use various data protocols and transmission mechanisms Can be done. For example, if the local area network is unavailable For example, connect to the host RS485, RS232, RS442, power line model Mu (powerline) It can be achieved by modem), or a dedicated telephone line, etc. .. Instead, a special model designed for use on such cables. Can be used. Each cell controller 102a-c covers a separate floor 130a-c It can be installed so that its exact configuration is changed by the system administrator. It is possible. On the floor 130a, the cell controller 102a is the antenna controller. It is placed on the ceiling 140a with the set of Joules 104a-c. Remaining floor The same equipment configuration is used for 130b-c. Antenna module 10 4a-d has good gain in the downward and horizontal directions and bad gain in the upward direction. Designed to provide, as a result, which of the antenna modules 104a-c By knowing if the strongest signal is being received from tag 101a, tag 101 The vertical position of a (ie, the floor) can be determined. Structurally A ground plane is placed behind each antenna to reflect the signal downwards. Next, Antenna Mo Know which of Joules 104a-c is receiving a strong signal from tag 101a By doing so, the horizontal position of the tag 101a is roughly determined. Antenna Moji The horizontal position of the tag 101a with respect to the tool 104a is the call signal 106. And each antenna mod from tag 101a based on the coupling round trip time of tag signal 107 To determine more accurately by estimating the distance to the tur 104a-c Can be done. From cell controller 102a and its antenna module 104a-d Each "cell" made covers a floor space of thousands of square feet. Each section Le works independently, with more cells without affecting the behavior of existing cells Can be added. If the user wants to place tags by "zone", then by zone One antenna can be placed. 1 or more tags moving down the corridor 1 Users who wish to track 01a-c are 20 along corridor 130a-c. Antenna modules 104a-d can be placed every few meters, tag 1 By measuring the distance of those antenna modules 104a-d from 01a Calculate the linear position of tag 101a. Triangulate the position of tag 101a Customers who want to install a sufficient number of antenna modules and have few tags 101a Must be within the effective range of at least 3 antenna modules Must be. Typical installation costs relatively low per square foot Covers a complete facility 110 with a combination of "zones" and "corridors", Occasionally improve a particular area with a sufficient number of antenna modules to position the tag Triangulate. RF design of tags Referring to FIG. 3, the tag RF circuit 300 is signal 1 at the tag receiving antenna 301. 06 is received and the tag signal 107 is transmitted by the tag transmission antenna 312. Tag RF The function of circuit 300 responds to the input spectral spread signal 106 by frequency conversion. Is Rukoto. The second function of the tag R circuit 300 is that of the microprocessor 308. Under control, the tag data is modulated into the output tag signal 107. Main departure In a preferred embodiment of Ming, the information output on the tag signal 107 is of the tag. Derived from sequence numbers, datagram headers, and mobile or low power indicators Includes tag data 309 such as The input signal 106 is preferably biphase from the cell controller 102a. Modulated or right-angled modulated, direct series spectral spread of the 2440 MHz band It is a signal. The signal 106 is received by the tag receiving antenna 301, and its ante The Na 301 collects the signal 106 and supplies it to the tag RF circuit 300. When the signal 106 is received by the tag receiving antenna 301, the Rx (receive) van Dopass filter 302 only signals in the ISM band with a tag of 2440 MHz Receive radar signals, electronic newsgathering signals, etc. Make sure to eliminate. In one embodiment, the filter 302 is located in the circuit board. Implemented as an embedded, etched bond stripline filter To. The signal 106 is then amplified by amplifier 303 to signal-to-noise ratio (SNR). Ensure that the received signal is mixed in the frequency mixer 304 without degrading To be true. Frequency converter 304 has a carrier frequency of 2440 MHz to 5780 MHz Convert or shift to Hertz. Input with a center frequency of 2440 MHz The signal is a phase-locked oscillator (PLO) with a center frequency of 3340 MHz. Mixed with 305 outputs. As a result, the difference frequency and bandpass fill Various harmonics removed by the data 306 Along with waves and harmonics, it produces a sum frequency of 5780 MHz. One fruit In the embodiment, the PLO305 has a phase lock loop with the following three inputs: Consists of a PLL: (1) Sump from a voltage controlled oscillator (VCO) Output; (2) Reference signal sound from 10 MHz oscillator: and (3) Micro Frequency program interface to processor 308. This is 3340 Produces a pure tone with good phase noise at the Gahertz tag LO frequency. In an alternative embodiment, the PLO305 produces a 1670 MHz signal sound, and then To double it to produce the desired 3340 MHz result. The next element of the tag RF circuit 300 is the biphase modulator 307, which is Under the control of the icroprocessor 308, it passes the signal of 5780 MHz unchanged. Or change the phase of the signal by 180 degrees. The modulator 307 is shown in FIG. As implemented as a single pole double throw RF switch 801 that supplies a 180 degree mixture To. On-off key (OOK) modulation, two-phase displacement (BPSK) modulation, multi-phase displacement (M) Uses several forms of modulation, including PK) modulation and quadrature amplitude (QAM) modulation can do. BPSK is the preferred form of modulation. Modulator 307 output Is fed to amplifier 310 and then filled by transmitter bandpass filter 311 The output of the filter 311 is output from the transmitting antenna 312 as a tag signal 107. Be sent out. Amplifier 310 operates at high frequencies, so it consumes a lot of power However, an alternative embodiment (as shown in FIG. 4) that eliminates the need for this amplifier 310 is preferred. I. The Tx filter 311 implemented as a 5-pole filter is the 15 of the FCC part. Necessary for conformity with the requirements of. The tag RF circuit 300 shown in FIG. 3 is a tag, along with an operable and trivial embodiment. It is intended to show the general function of 101a-c. Those skilled in the art store power Combine multiple features into a single element to get the most out of the available parts Or it should be possible to perform the same function with a custom ASIC U. FIG. 4 shows an alternative embodiment, which has the same basic functionality as shown in FIG. Satisfied, but has fewer elements and uses less power. Shown in Figure 4 The essential difference between circuit 400 and circuit 300 shown in FIG. 3 reduces the number of elements. To save power (for example, amplifier 310 is removed) The modulator 406 is located in front of the frequency mixer 406. Instead of frequency mixer 304 (Fig. 3) or time delay element 1505 (Fig. 13) Can be responded by other methods using other signal transmission discriminators. example For example, tags such as tag 101a have backward confusion, frequency conversion by mixing, and harmonic picking. Frequency conversion by taking, frequency conversion by collecting low harmonics, or signal delay (SAW) You can respond using (such as by device). Although not shown in Figure 4, what is desirable for a tagged RF circuit is PLO4. For both 07 and clock timing in microprocessor 405 The use of a common crystal reference signal. The exact timing, if it doesn't matter At the very least, it is an important form of the system, with the tag 101a transmitting the tag signal 107. Allows the cell controller 102a-c to predict when Same crystal Reference signal clock timing for PLO407 and microprocessor 405 By using it in the cell controller 102a (as described below) Accurately calibrate the source by measuring the phase shift in the signal and follow it It is possible to synchronize the clock timing. Although not shown in Figure 4, what is desirable in some applications is transmission. The antenna 409 and the receiving antenna 401 are combined into a single element to create a single antenna structure. It is an embodiment using a diplexer having a structure. The method of powering tags 101a-c depends on the application. (Figs. 3 and 4 are It should be mentioned that the power supply of the device is omitted. ) Typically, tag 101a is back Powered by Terry, the RF stage is swept under the control of microprocessor 405. Switch on and off. In a preferred embodiment, the microprocessor 405 has low power. It shifts to a force state, where it simply waits until it is time to restart tag 101a. Wait purely. In an alternative embodiment, the RC time constant in circuit 400 is timed. Used as a clock, all tag circuits 400 are turned on and off under analog control. Return. Using the tag RF circuit 300 or 400 of Figure 3 or 4, tag 101a is set. It is within the effective range of two of the controllers 102a-c, and they are cell controllers. If the trawler transmits pseudo-noise with low cross-correlation characteristics, then tag 101a has both signals. Respond accurately to Will do. Tags 101a-c charge up and charge down in milliseconds Requires a period of order. During these short periods, the tag 101a is typically -c may not be stable enough for use, but nevertheless send a Will radiate RF to the radio channel through the TENNA 409. Wireless band is controlled For limited high performance applications, a microprocessor controlled switch By adding chi to the tag's transmission chain, such spurious emissions can be eliminated. Wear. The tag RF circuits 30 and 400 shown in FIGS. 3 and 4 are related to pairs having different frequencies. It can be used in. The general approach described above is the acceptable FCC spectrum It works on either two of the diffusion bands. For example, FCC Rule Part 15 The following combinations are allowed for unlicensed radios under .247: Conversion from 915 MHz to 2440 MHz, Conversion from 915 MHz to 5780 MHz, Conversion from 2440 MHz to 915 MHz, Conversion from 5780 MHz to 915 MHz, Conversion from 5780 MHz to 2440 MHz. However, spectral diffusion operation is not required; two licensed narrowbands are used It is possible. But for the rest of the discussion, 2440 and 5780 megahels We assume a spectral diffusion operation in Tsu. Tags with time delay The tag RF circuits 300 and 400 shown in Figures 3 and 4 provide frequency division multiplexing access. use. That is, the tag RF circuits 300 and 400 receive signals at different frequencies. And radiate. As shown in FIG. 13, the alternative embodiment 1500 is a time division multiplex. Use Seth. For the purposes shown, the tag circuit 1500 shown in FIG. 13 receives the receiver. Obtaining one frequency as an input with the INTENA 1501, for example 915 MHz, Same signal through transmit antenna 1508 at the same frequency after a 1 microsecond delay Suppose it releases. Like cell controller 102a Cell controller sends burst call signal 106 every 2 microseconds Suppose. A tag such as tag 101a receives this signal as an input antenna. Obtained through 1501. Then, as in Figures 3 and 4, the signal is required Pass through the element 1502-1504. Then use the time delay element 1505 to 1 my Delay by black seconds. The signal then passes through the transmit bandpass filter 1507. , Emitted from the transmitting antenna. SAW device as time delay element 1505 Can be used. During the delay period, the cell controller stops transmitting and its ring The reflection of the call signal 106 under the precincts is reduced to the minimum level. Full dual frequency circumference Although it has a lower bandwidth than the wavenumber shift approach, this half-duplex approach has a single frequency. Allows several movements. Like frequency change tags, delay-based tags provide a response signal. It can be modulated by a 180 degree phase shift. In other respects, as shown in FIG. The tag design 1500 is similar to that shown in Figures 3 and 4. RF design of cell controller FIG. 6 shows the radio stage of the cell controller 102a. Antenna module, for example For example, the configuration of the antenna module 104 is shown in FIG. Cell controller 102 a and its remote antenna module 103a-d are jointly included in the baseband square wave Modulates force to 2440 MHz carriers, resulting in 2440 MHz Filter the signal to meet the FCC transmission request and filter it Ringed 2440 MHz signal through selected antenna module Send and return 5780 MHz tag response through the same antenna module Receive and extract the I (in-phase) and Q (quadrature) components of the demodulated baseband signal , The result is digitized for further processing. Figure 10 shows the key components of the cell controller digital subsystem 650. Su. In summary, the digital subsystem 650 has a baseband input signal 601 Provide and receive a demodulation response 107 from tag 102a after a few nanoseconds. My above The cross processor 1001 (a) modifies the baseband input signal 601; (b) ) Change chip rate, pseudo-noise sequence length, and / or pseudo-noise sequence code (C) Transmission frequency 610 and radio of radio transmitter 1002 in a narrow band Change the reception frequency of receiver 1003; (d) wireless transmission Change the transmit gain of device 1002 and the receive gain of wireless receiver 1003; And (e) wireless system by switching the antenna module 104a-d The behavior of the system can be changed. The demodulation response 107 from tag 102a is I (homeomorphic) by radio receiver 1003. And Q (quadrature phase) components, digitized by digitizer 636 To. For example, the integer DSP processor 1004, which is TMS320C54, is a digitizer. It reduces the output from Isa 636 and performs high-speed correlation operations. Two-phase displacement change When keying (BPSK) is used on the transmitting side, the I and Q channels are correlated separately. It is kicked and combined. For Quadrature Phase Modulation (QPSK), each channel is Must be correlated to the series once, a total of two times, once correlated to each series There must be. Correlation data from the integer DPS1004 is, for example, Pentair. It is processed by a microprocessor 1001 such as a CPU processor. Cost reduction Low power x86 processor and TMS320C for high performance and high performance Floating point DSP processors such as 30 can be used. Micro Pro Communication between Sessa 1001 and host computer 105 is TCP / IP protocol Achieved using col, preferably by Ethernet. The data input to the transmission chain is the baseband input signal 601 and it is suspected It is a similar noise diffusion series. The length of the series and the code encoded in the series Is set by the cell controller microprocessor 1001 and requires signal processing It can be changed depending on the request. A 31 or 127 bit sequence is typical, Gives compression gains of 15 dB and 20 dB, respectively. 2440 MHz And the 5780 MHz band supports a 40 MHz baseband input signal 601. It is possible and the cell controller 102a will allow the use of this full bandwidth. Designed to. Figure 5A-5G shows the passage through various stages of the cell controller RF circuit 600. The call signal 106 is shown. Figure 5A shows the square wave baseband included in the modulator 500. Show power. Figure 5B shows this digitally correlated baseband input 510. Is shown. Figure 5C shows the output 520 from the modulator 602 at 2440 MHz. Observed by a spectrum analyzer as the center. Figure 5D is 5780 mega Tag signal 107 space centered on Hertz Observation of the couture analyzer 530 is shown. Figure 5E shows the demodulation response from tag 107. Shown and separated into its I (quadrature) component 545 and Q (quadrature phase) 540 components There is. Figure 5F shows the digitally correlated I and Q components 550. Figure 5G shows the negation of the quadratic derivative of the correlated waveform with the I and Q components combined. Modulator 602 (Figure 6) has a baseband input 601 with a 2440 MHz carry Modulate to a. Various forms of modulation are available and are well known to those of skill in the art. BP For SK modulation, the modulator 602 is actually a unipolar double throw FF switch 801. It is signaled to the 180 degree hybrid coupler 803 as shown in Figure 8. To supply. Modulator 602 is preferably implemented as a QPSK modulator, which is a BP Duplicate the SK modulator from the other with a 90 degree 1 channel offset, each channel Is driven by different baseband sequences with acceptable cross-correlation characteristics. Higher-order modulation is also possible. Hundreds of megahels due to modulation by modulator 602 A side lobe is created over the tsu, which is filtered to meet FCC requirements. Must be done. The 2440 MHz band has a proximity band, which is non- It always gives rise to strong filtering requirements, which in the illustrated embodiment Best shown using SAW filter 607, which combines high bandwidth and strict stop. Is done. Wider pass range is faster chipping at baseband input signal 601 Supports chipping rates, but narrower pass areas have a wider frequency die Providing the opportunity to use Varsity, Preventing Interference, and / or Advanced Credit Support the No. processing method. Modulator 602 is identical to available IF filter 607 Do not operate in frequencies, typically in the range of 200 MHz to 400 MHz Must be. Preamp 606 required before SAW IF filter 607 Yes, the output of that filter needs to be amplified by amplifier 608. Like all other RF oscillators in cell controller circuit 600, transmit IF The shaker 605 is phase-locked to a 10 MHz crystal oscillator source 603 and its saw The 603 is distributed to each oscillator through the filter and distribution network 604. To. 10 MHz source 603 prevents excessive baseband phase shift To be within a few kilohertz of the 10 MHz source on the tag. Next, the output of IF filter 607 (from amplifier 608) goes to mixer 609. More phase Mixed with the output from the Lock Oscillator (PLO) 611, the key is 2440 MHz. Converted to carrier frequency. The frequency of PLO611 is essential to prevent interference Various advanced signals to provide the required frequency diversity and / or Due to processing technology, it changes within a narrow range under the control of microprocessor control unit 610. Can be changed. The degree of frequency diversity available is IF filter 6 In connection with the use of 07, narrower filters allow slower chip rates, Has more frequency flexibility. Unwanted harmonics from the output of mixer 609 And the filters typically needed to remove the difference frequency are shown in Figure 6. Not. Next to the mixer 609 is the driver amplifier 612, which powers the signal 106. Increase the level, thereby connecting cable 103a to remote antenna module 10 Can be tribeed down to 4a, and it also has a bandpass filter 613 Buffer the output of mixer 609 for. RF bandpass filter 613 , Required to eliminate FCC-incompatible output from mixer 609. Oriented In the sex coupler 616, the signal 106 is a remote antenna module, for example an antenna. A port for inspecting signal 106 before it is sent to module 104a-d. To provide Attenuator 614 is under the control of microprocessor controller 615, tag 101a- Signal processing software reduces output power when d is found to be nearby And is possible. This is because nearby tags are overdriven by the cell controller Situations known to be, and / or signal processing software This is useful when you need to operate the device in a more linear range. The signal is then sent to the diplexer 618, which is the transmit signal 106 and the receive signal. Join 107 on a single wire. Diplexer 618 is high pass / low pass The filter coupling is 619a, which attenuates the received signal 107 to the transmitting side. The transmission signal 106 is attenuated with respect to the receiving side. Tx bandpass filter 61 Due to the presence of 3 and Rx bandpass filter 624, the work of Diplexer 618 Is not so strict. The cell controller RF stage 600 shown in Fig. 6 has one remote antenna at a time. Supports the Tour 104a-d. Multiple antennas from the same cell controller To support The system requires switch 619, which switch 619 is a microprocessor. The control unit 620 can quickly switch from one antenna to another. Noh. Switch 619 acquires RF and makes it one of n cables Where n is, for example, 8 or 16. Also, switch 619 is selected Provides DC power to the selected line. RF signals include capacitors (not shown) Coupled to the cable that has its capacitors provide DC isolation and its DC power Is coupled to a cable with an RF choke to provide RF isolation. thus, DC and RF are transferred together to the selected antenna through a single coaxial cable Move. The rise time of direct current in the antenna is within the range of 100 microseconds. Effective resistance of circuits in teners and capacitors and antennas required for operation And limited by the characteristics of the capacitor. Micro antenna switching time DC power to the antenna is given before the RF is switched to provide within seconds available. With reference to FIG. 7, in the antenna system 700, the coupled DC and RF signal is coaxial, for example cable 103a from cell controller 102a It arrives through a cable. Bias T-shaped part 701 is RF signal from DC signal 712 Separate No. 710. DC signal 712 is sent to Tx / Rx power control logic 702 It removes noise from the line and is accurate in the simplest embodiment. It is a filter for providing a 5 volt power supply. Bias from T-shaped part 701 RF output 710 is sent to Diplexer 715, which is cell controller 102 It is the same as Diplexer 618 in a. Then this is FCC with amp 703 Amplifies to an acceptable power level and is filtered by filter 704 Eliminates line and amplifier noise that conforms to FCC regulations. Obtained as a result The signal is then sent to the transmitting antenna 705. In the present embodiment, the transmitting antenna 705 and the receiving antenna 706 are packed. Cheerley, providing vertically reduced energy and horizontal d. Diffuses energy, resulting in no wasted power on floors and ceilings The minimum amount of power is radiated upwards. 5780 MHz response from tag 101a 1 07 is filtered by filter 707 and amplified by amplifier 708 , Cell controller down cable 103a Sent up to 102a. The system uses a standard length cable 103a-d, eg 20 meters Designed to be. Cable extension module 900 connects two lengths of cable Continue to maintain extension cable length. Seeing Figure 9, the key to Module 900 The element uses the DC power from the cable 103 to drive the low noise amplifiers 903 and 904. Moving, they provide enough gain to drive the next part of the cable. Bias T-shaped parts 906 and 907 separate DC power 910 from RF signal and dip Lexa 908 and 909 act to separate transmit signal 106 from receive signal 107 To make. Referring to FIG. 6, antenna module 104a to cell controller 102 The signal back to a passes through the switch elements 621, 619 and the diplexer 618. To the receive RF chain 622 of the cell controller. The signal is preamplifier 623 And the bandpass filter 624 pass through the coupling, its exact configuration is the selected part It changes depending on. Digitally controlled under the micro port setter control unit 626 Receive attenuator 625 when the tag 101a is known to be nearby Used to prevent saturation of the receive chain. This is the correct correlation and others Prevents the loss of the relationship between the I and Q components of the received signal 107, which is required for signal processing in It is necessary for. The signal then enters IQ zero IF demodulation circuit 627-633. As mentioned earlier In addition, the Rx frequency control unit 635 of the microprocessor is its relative in the transmission chain. Must be set to work with. The result signal shown in Fig. 5E as an example is It is sent to digitizer 636 (Figure 10) in preparation for digital signal processing. In the above embodiment, the cell controller sends from only one antenna at a predetermined time. Simplified based on the assumption that it will be received. Transmission and reception antennas are mutually independent Improved performance is achieved by making a standing choice. Cell control The software in the roller is which antenna module receives the best signal from the tag Decide if you believe. For example, a specific tag such as tag 101a is an antenna, for example. For example, if it is close to the antenna 104a, the antenna 104 is from tag 101a. Will receive a strong signal. Next, the cell controller 102a has an antenna 10 A signal such as signal 106 can be transmitted from 4a, and the antenna Receive alternate response 107 at 104b, 104c, and 104d To. This is the signal transmitted that the antenna 104b-d would have received 1 Signals received independently from 06 and each of the antenna modules 104b-d Stronger signal at antenna 104b-d compared to signal with 107 Give rise. Design 1600 shown in Figure 14 has multiple receive chains operating in parallel 1610a-16 Offer 10n. Each reception chain 1610a-1610n is an IQ demodulation circuit, digital Correlation shown as a tizer, and an integer DSP, for example the integer DSP1620 Includes attached elements. Performing each receive chain on a separate card offers tunability To serve. Use multiple receive antenna modules for the same transmit signal The cell controller signal processing software uses spatial processing techniques to multiplex It is possible to separate the effect. These methods are degraded by multipath Take advantage of the fact that the response is different for each antenna. Bit detection In an ideal environment, a simple triangular correlation peak is received, as shown in Figure 5B. It can be obtained from the tag signal 107. Distortion introduced into the wireless chain, especially indoor dendrogram The distortion caused by the Lucipas effect is distorted but nevertheless distinguishable. A correlation peak is generated and its function is shown in Figure 5G. For the purpose of bit detection In addition, the essential point is to reliably detect the existence of a series of correlations, which are the values. Shows the operation of FIG. 11 shows a method of acquiring tag data from a series of correlations. In the left half of chart 1110 shown in FIG. 11, the tag transmits 0. .. This is a tag modulator 307 to pass the call signal 106 unchanged. Is achieved by setting. Receive tag signal 107 is related to transmission pseudo-noise sequence When linked, essentially the same correlation peaks occur. Three such Peaks 1120a-c are illustrated here. During the time of the fourth correlation 1120d, The phase of the modulator is changed by 180 degrees, and 1 is set as shown in Chart 1110. Shown. The fourth correlation data peak 1120d changes because the modulation changes in the middle of the bits. Formed and best ignored. The 5th and 6th correlation peaks 1120e-f are 1 Accurately reflects the 80 degree shift. In the cell controller, the pseudo-noise sequence is changed under the control of the microprocessor. Can be transformed. When the presence of the tag is first detected, as shown in Figure 11. You must use a relatively short series. The bit timing of the tag is confirmed once Once done, a longer sequence can be used to improve the SNR, it Is useful in distance measurement. An important consideration not shown in Figure 11 is the signal between the in-phase and quadrature phase components of the received signal. The lance drifts over time. This is the cell controller 102a And the 10 MHz source in Tag 101a typically differs by a few kilohertz That is. This factor is the change in the received signal in phase and / or quadrature. Indicates the phase difference between continuous correlations that can be detected in the baseband by showing It can be adjusted by. As mentioned earlier, using this same adjustment process The tag clock can be adjusted with respect to the cell controller clock, and the tag Accurate tag charp time without the need to accurately measure bit transition timing Enables prediction. Interaction between cell controller and tag Each tag is a self-supporting unit, which in any way is a concern from the outside world. I can't get it. Each tag is the only identity code associated with it at the time of manufacture ( UID). The tag wakes up periodically and any input 2440 for a short time Converts the Gahertz signal 106 to an output 5789 MHz signal, on the other hand its UID And other data is modulated into the output signal 107 it chirps (transmits). Ta Does not communicate with other tags. The tag did not explicitly respond to the call signal, 244 Simply responds to any input signal 106 in the 0 MHz band, the band is close It can also contain a pseudo-noise sequence from the cell controller antenna module 104a Yes, it may not be included. This approach is the design and manufacture of tag 101a Is greatly simplified. For some part of that time, two or more tags respond at the same time. In many cases, One of the two tags returns a stronger signal than the other tag, during such a collision Some data will be lost. Avoid collisions that occur in iterative patterns So the tag randomly "wakes up" at time, chirps those UIDs and it Et al. Pseudo-random number generation including tag UID It can be calculated based on the genitals (both by the tag and the cell controller). example For example, for tags that chirp about every 5 seconds, the tags are suspected between 0.0 and 2.0. Generate similar random numbers, add them to the minimum delay time of 4.0 seconds, 4.0 to 6.0 It produces a series of delay times that are evenly distributed over the seconds. An announcer to a pseudo-random number generator, such as an input from an internal clock or RC circuit delay It is possible to change the seed over time using log input, but cells Controller 102a can accurately predict the chirp time of known tags A pure digital scheme is preferred for this. A typical pseudo-random number generator is Has the form below: N = rand (seed) Equation 1 The resulting N is used as a seed for the next pseudo-random number in the pseudo-random number sequence. Used. When using this kind of pseudo-random number generator, two tags use the same species And their tag signals repeatedly collide. In addition, the tag clock With a small difference in, all pairs of tags end up with this same over a certain amount of time Drift through the expected state. To prevent these situations, as described above It is desirable to introduce the UID of each tag in the delay time for that tag, and each tag Different pseudo-random numbers for the game, ie: Delay = f (N, UID) Expression 2 Produces. One simple example of such a function is: Delay = Xor (N, BitRotate (UID, AND (N, 1111)₂))) Equation 3 Referencing Equation 3, N = Xor (Delay, BitRotate (UID, AND (N, 1111))₂))) Calculate By doing so, UID, Delay, and AND (N, 1111)₂) Can be reconstructed from seeds Noh. Referring to FIG. 12a, one embodiment of the tag datagram 1400 is a cell. Header 1401 to allow the controller to detect the presence of the tag Includes, then the identifier preamble 1402, then the tag UID 1403 There is. Header 1401 can be zero length. Identifier pre-ambu 1402 is actually used as an effectiveness check such as Cyclic Redundancy Check (CRC). Can be done. Simple enough delay function And with high clock stability, the cell controller has a datagram of 1400 Inferring a tag chirp sequence by showing the timing of a series of chirps Can be done. Referring to FIG. 12b, in another embodiment of datagram 1410, the tag Adds delay information 1414, which causes the cell controller to tag the data To be able to predict the transmission time of the next and subsequent chirps of the 1410. Equation 3 In the example of, this information is based on the data: Delay and And (N, 1111).₂) Will be included. With reference to FIG. 12c, in another embodiment of the datagram 1420, FIG. The shorter headers used in the 2a and 12b datagrams 1400, 1410 Used and sent UID 1423 contained in tag datagram 1420 Ensure that the cell controller has previously had enough time to detect the presence of the tag Try not to. Attached to the datagram 1420 is the transmission of the next chirp Delay 1425 and cell controller first received in datagram 1420 Even if you don't have enough time to identify the tag identity from the chirp Cell control the time when the next will chirp its datagram 1420 -Make it predictable. Next, the cell controller predicts this next chirp As expected, the identity of the tag at that time can be confirmed. Once the tag is identified, The controller duplicates the tag's pseudo-random number generator and everything in the future with the tag Calculate the chirp time of. In the tag datagram 1420 of Figure 12c, U Insert a set of special sync bits 1424 between ID 1423 and delay information 1425 And make sure you decide when UID 1423 will end. In this case, UID14 23 must be specified not to include synchronous series or vice versa. Figures 12a, 12b, and 12c show selective data sections 1404, 141. Has 5,1426, which the tag sends data to the cell controller Is possible. These sections 1404, 1415, 1426 are inside tags Data from, such as mobile detectors or low power indicators, or tags When attached to humans, it can be used as a tag for metabolic information for medical remote measurement. It can include data from attached external devices. The identifier preamble associated with the tag UID precedes the tag UID. This identification Child preah The amble will predict the tag without having to decode the full UID of the tag Allows the cell controller to quickly confirm that it is chirping To. This is due to other actions such as communicating with different tags that are close to other antennas. Free the cell controller. Identifier preamble 1402, 1412, 1 422 and tags 1403, 1413, 1423 are externally configured and appropriate If so, it can be specified to include an error correction bit. The tag's UID can be hardcoded within the tag (eg) As a serial number). Tags are grouped based on their UID You can associate different groups with different cell controllers To. For each cell controller, which tag is associated with the cell controller Contains information about whether it belongs to a group (received from another source). Cell control When the cellar receives the tag signal, the cell controller extracts the UID information from the tag signal. The output tag signal is due to a tag in the group associated with the cell controller. Determine if it was sent. In the tag datagrams 1400, 1410, 1420 of Figure 12a-12c , Delay information fields 1414, 1425 and data fields 1404, 1 415 and 1426 can also include error correction bits. For simple processing , Data can be reduced to a half-byte stream .. The tag is a table to determine which value to send for a particular half byte You can refer to the half-byte values in the table, and the table will be converted to half-byte values. In addition, it contains, for example, an 8-bit value that indicates data correction information. Single cell controller Is a complete set of three datagrams 1400, 1410, 1420 shown in Figures 12a-c. Can be processed. Datagram type selection requires application for specific tags It will depend on the requirements. The amount of time it takes for the cell controller to detect the presence of a tag is the cell controller It changes depending on the nature of La's design. For example, 16 cell controllers 100 microseconds to switch antennas when circulating tena Time is important. The first time a tag signal is received by the cell controller To ensure that the tag is identified, the header of the tag datagram is all Enough time to make an attempt on the antenna It must be long enough to give the cell controller a gap. Performance 2 or 3 microseconds increase in header if the request is in the range of 100 tags per second Addition is allowed. But in higher performance demands, or in tags Cell controller performer when power consumption must be minimized Tag datagram 142 of the type that improves the function or is shown in Figure 12c Either use 0 is required. Antenna and / or circumference by predicting transmission time from a particular tag Serco to better calculate tag position using wavenumber diversity Trolla can collect tag information from various antennas in an organized way it can. If the tag is responding exactly when it is expected to respond, then Cercon To reasonably confirm that the trawler is receiving the signal from the correct tag The controller needs to detect all the bits transmitted in the tag datagram There is no. The correct identifier preamble that arrives exactly on time is arguably It is from the predicted tag. This allows the cell controller to communicate with the tag It provides an opportunity to make attempts at various antennas that are capable or impossible. Shorter if you need to track tags between sending tag datagrams Tags can be configured to send more frequently. For example, the tag is that More if the datagram was configured to chirp every 10 seconds on average Configure tags to send short codes more often, eg every 0.5 seconds You can also do it. Make this short code as short as 1 bit long and send a few microphones It can only take a second. This makes it so hundreds of times per second Even a small transmission will consume only a small percentage of communication channels. Cercon The trawler can predict the exact timing of each such transmission, and so on. To harmonize each signal with the source tag based on the transmission time. The error correction code is A long chirp from one tag is typically a quick chirp from another It can be configured so that it is not corrupted by. Cell controller La has the data to predict most of such collisions. When a tag is first introduced within the scope of the cell controller, it will be decoded for a different tag. Collisions between message transmissions occur in unpredictable ways. Newly introduced in the effective range Send by a tag, or a tag that instantly increases its send rate (eg, Mobile detector or panic Transmission by (such as responding to a button) is expected by cell controller 102a It cannot be done and causes data collisions. But once the tag is identified , The previous collision is modeled and suspicious data is ignored. Instead, two If the signals from the tags collide, the signal received by the antenna from one tag , The cell controller unannounces to be stronger than the signal received from another tag You can choose tena. In more advanced tag design, cell control that the tag is working Cell control as a means of sending tag information and instructions during the time that La is aware of -La prepares. Such instructions should be communicated to the device attached to the tag Can include instructions. The cell controller is most simply an on / off key-in Shows 1 or zero by on-off keying and for more advanced tags Dow such information by flipping the pseudo-noise bit sequence so that Can be loaded. Generally downlink (download) approach Is driven by cost and form requirements, high bit downlink transmission rate, It requires a more expensive receiver that consumes more power. Therefore, a single cell The controller has read-only tags, read / write tags, and fast read The take / write tags can be maintained at the same time, and the cell controller has a specific tag. Adapts one's behavior depending on the form maintained in the game. The transmission timing from the tag to the cell controller is the item to be tagged Dependent. Help to send infrequently, for example once every minute Materials and equipment can be set. For example, tags attached to people in shelters Is required to be sent more frequently. Tag read / write version The transmission timing should be transformed into an instruction from the cell controller. Can be done. The alternative tag design allows the transmission time to be changed based on environmental factors. Example For example, place a movement detector inside the tag and reduce the transmission interval while the tag is moving. Can be done. As another example, when a tag is tampered with, the tag becomes more frequent and more powerful. Can send. As another example, the tag is a slightly modified electronic article monitoring (EAS) The device is within the effective range of a standard EAS detector, including the device. You can have the tag send its UID more often when it is present. More general If the tag is attached to another electronic device, The transmission interval can be changed under the control of the device. Tag power Tags 101a-c have low RF power to increase their portability and longevity Send the force level. In addition, the tag signal transmission 107 is only for a few milliseconds. Designed to be. So even if the tag responds with its UID every few seconds Careful tag design brings the tag's battery life closer to the battery's own shelf life It is possible to kick. Introduced mobile detector on tag for even lower power usage And, for example, when the tag is stationary, you can avoid sending frequently. Wear. In some situations, the battery can be installed by installing it in the mounting mechanism. Can be exchanged. For example, reusable tag electronic Attach the bracelet to a disposable patient bracelet and include the battery in the bracelet Melt. As another example, attach the battery to the clip on the ID bracelet be able to. More generally, cheap and disposable active RFID tags Attach the battery to other parts and take the electronics to other, more expensive parts Can be attached. If the item to which you attach the tag is the power supply itself, connect the tag to that power supply Can be tapped. This approach designs the tag inside the device itself If you can (such as for a handheld computer), or the equipment and It is very realistic when the power supply is large (forklift etc.). Yo Larger power supplies allow longer tag coverage. Tag position estimation The tag signal 107 is (1) between the circuit and the antenna module 104a-d. Known in cell controller 102a to send call signal 106 by wiring Fixed delay, (2) When fixed in antenna module 104a and tag 101a Delay, and (3) call signal 106 and tag signal 107 propagate in the air Received at the time, which is the total time for. Since (1) and (2) are fixed, the call signal 106 and data of (3) Pay attention to the propagation time of the signal 107 in the air. By cell controller 102a The duration of the pseudo-noise series modulated on the 2440MHz carrier signal is the signal 10 Must be greater than the combined propagation time of 6 and tag signal 107. Pseudo noise series Techniques for correlating are known in the prior art. When there is no multipath effect , The cell controller 102a receives the tag signal 10 as shown in FIG. 5B. A simple triangular correlation peak can be obtained from 7. But most indoor rings At the border, the tag signal actually received is more similar to that shown in Figure 5D-5G. ing. Indoor wireless signals include whiteboards, fluorescent lights, file cabinets, and d. Due to reflections from various surfaces such as the shaft of the elevator, the beam of steel, etc. Receives the Lucipas effect. When tag 101a sends tag signal 107, tag directly The sum of signal 107 and reflected signal is cell controller antenna module 104a Received at. Various approaches to extract correlation peaks from such information Can be used, available signal quality, processing power and required puff A specific approach is selected depending on the performance. A 40 MHz chip rate vs. a rise time distance of approximately 25 feet It produces a corresponding peak with a rise time of 25 nanoseconds. Use round-trip propagation time Because the position of the tag is calculated using, the accuracy of a single chip is any advanced signal. Allows calculation of tag distances within 12 feet without the need for processing. The approximate position of the tag is when the correlated signal-to-noise ratio exceeds a given level. It can be calculated by paying attention to whether it rises. A small number of types Improved precision by trying the rear frequency and choosing the one that rises first Degrees can be achieved; such frequency diversity is shown in Figure 4-6. Maintained by a wireless system. This approach is sensitive to the signal-to-noise ratio of the system It's a feeling. An alternative approach is to find the peak of the correlation function. About the improved result Then, as shown in Fig. 5G, the negation of the quadratic derivative of the cross-correlation function is taken, and its peak position is taken. The signal delay is calculated by finding the device. MUSIC algorithm known to those skilled in the art for maximum accuracy To use It can be done, and accuracy within the 0.01 chip range has been reported for it. MUSIC requires frequency diversity, which is described here and is shown in Figure 6. Maintained by a wireless system. The method is a delay profile data vector Based on the decomposition of the eigenvector space of the pseudo-noise correlation matrix of. Each lap distinguished Frequency die when wavenumber provides information for solving additional multipath components Varsity is required. For tags that remain almost stationary, the required day Data can be collected and the calculation is completed as a background process. For application to inventory Therefore, when the movement detector must be installed in the tag and its position must be recalculated. Always inform the cell controller. Appropriate data collection time, antenna diversity, frequency diversity, etc. Or in the presence of terrible multipath effects in situations where processing power is not available Even, heuristics can be used to calculate the position of tags. To conventional technology Each Ann can be used as needed, using a variety of well-known techniques. The direction to Tena can be inferred. In many situations, exact accuracy in the calculation of tag positions is not required, Nevertheless, it will be important to calculate the tag position in relation to the floor or divider. As shown in Fig. 2, the antenna extending downward is used as the ceiling to distinguish each floor in the building. This can be achieved by placing the antenna on the floor (or on the floor). Similarly In addition, the antennas placed on the horizontal partitions are positioned relative to these partitions. The placement can be determined. Low sensitivity to multipath effect, relatively narrow The wide antenna can be pointed at the exit or other points. Place the cell controller antenna 104a near the computer screen and place the screen It is possible to have an effective range corresponding to the viewing angle of. Then the scope Automatically configure the operating system for people in, or who is in range Blank screen for security purposes based on who is out of range Software can be configured. Copier, microfilm reader Similar ideas can be used in connection with restricted equipment, etc. A single antenna module contains three separate antennas arranged in a triangle Can be taken. Compare phase differences using in-phase and quadrature phase components of the return signal By The display of the angle can be determined. In high frequency embodiments such as 2.45 GHz , Such antennas can be within a few inches of each other and are very effective To. When to analyze the correlation profile using heuristics and start the correlation, That is, estimate the time when the correlation peak became distinguishable from the "noise" baseline. Can be Frequency diversity can provide a variety of samples, You can choose the best of them. Improved speculation shows correlation peaks , One of the well-examined typical correlation profile terms and pattern matchon It can be achieved by For calibration purposes, place the tag in a known fixation position Tags that can be placed in place and pass near these locations have similar correlation pros Will indicate a file. Existence of obstruction (intentional) using such fixed tags Or an object that unintentionally emits disturbing radio waves) and tries various anti-jamming methods A real-time testbed for can be provided. Antenna diversity is paramount to improving tag position calculation accuracy It is a tool. If low accuracy is required, only one or two antennas The antenna can be arranged so that it is within the effective range of a predetermined tag. This In the case of, there is insufficient data for triangulation, and the existence of tags is always checked. Enough to put out and estimate the distance of the tag from one or two antennas Only information exists. The approximate orientation of the tag is designed for that purpose and is a conventional technique. It can be inferred from the signal strength of the antenna, which is well known to those skilled in the art; Such orientations tend to reflect the strongest received signal, which is a significant multipath component. Note that it will include. On the contrary, for areas that require high accuracy , The diversity of the relatively narrow beam width antenna can be installed at the entrance, for example. It also provides a clear image of the position. Antenna diversity also provides system adjustability. Tag position Substantially for other facilities or parts within the facility that do not require highly accurate calculations Omnidirectional and / or ceiling-mounted antenna, effective range square fee Due to the relatively low cost of each unit, they can be installed relatively apart from each other. High For facilities or parts within facilities that require high position accuracy, place them at close intervals. And / or directional antennas provide high accuracy at increased cost Can be Cell controller operation The design of the entire system and the transmission interval of the tag signal are generated in a pseudo-random manner. The fact that it is done gives an opportunity for reliable operation. Dispersed at the entrance of a safe facility A special code that can be tracked through the facility and when the tag is modified Can be radiated. Tag code determined by monitoring tag response Yes, but the tag transmission interval can be configured so that only the tag and host know It changes according to the algorithm and cannot be determined directly without destroying the tag. Noh. Tags are, for example, for reprogramming the code and transmission interval It can include elements, such as physical elements. For example, a photo ID that includes a tag , Potentially in the context of biometric technology, the person holding the photo ID is safe It can be reprogrammed each time it passes the checkpoint. Multiple celcons covering somewhat overlapping areas to cover the entire facility A trawler can be installed. Each cell controller searches and collects data Works according to the collection method, but fast movement between antennas, pseudo-noise code, chippy Change changes, etc. look like random noise for another cell controller Eh. In addition, codes with known cross-correlation characteristics, such as Gold Codes, etc. The host computer uses various cellcons, especially the code used to search for tags. Can be assigned to a trawler. Instead, the cell controller is a lander You can switch the pseudo noise selection on the basis. For tags on the boundary between two cell controllers, each cell controller La reports the distance of the tag from the antenna module. Central host 105 Collect and organize the data of, and calculate the position of the tag. Various pseudo-noise codes are available for use by the cell controller .. So one code is receiving interference from another user of the spectrum If so, the cell controller can choose another code. In essence The tag, which is a calling device, does not need to know the specific code in use. Similarly If another user is having problems, adjusting the center frequency somewhat it can. Other embodiments also fall within the scope of the claims below. For example, the process of the present invention is actually carried out. Order to go The introduction can be modified by one of ordinary skill in the art and still achieves the desired effect. To be done.