JP2008002866A - Position-detecting system and position detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position-detecting system having a simple constitution, as well as, accurately synchronizable base stations. <P>SOLUTION: The position-detecting system comprises a reference station 101, the base stations 102-104, a position calculator 105 and a communication terminal 106. The reference station 101 is disposed at equal distance from the base stations 102-104. The base stations 102-104 are triggered by a reference signal transmitted from the reference station 101 and receive a measurement signal transmitted from the communication terminal 106. The position of the communication terminal 106 is calculated, by aggregating the arrival time differences. Since the reference station 101 is disposed at an equal distance from the base stations 102-104, the time when the base stations 102-104 receive the reference signal 110 is the same among the base stations. Thus, the arrival times for the measuring signal are measured accurately at the base stations 102-104. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position detection system and a position detection method for detecting the position of a communication terminal.

  Conventionally, it has been technically difficult to detect the position of a person or an object in the space and track them, and social inefficiency and social loss caused by insufficient management of the position have been enormous. For this reason, various control technologies and management service businesses have been proposed that accurately detect these positions and use the detected position information as values. For example, the mainstream method is to detect the position of the target person or object by attaching the communication terminal to the person or object and detecting the position of the communication terminal. Monitoring, life assist robot control, medical equipment and medicine location management at medical sites, and article management in warehouses.

  As a position detection method of a communication terminal used indoors, for example, a cell ID method (Cell-ID method) for detecting a position of a mobile phone from a relationship with a service area of a cellular base station, between a communication terminal and a base station Field strength detection method (RSSI method) that detects the position by using the fact that the field strength depends on the distance between the two, and the fact that the wave arrival time between the communication terminal and the base station depends on the distance between the two And arrival time difference detection method (TOA method, TDOA method) for detecting the position. Among these, the TDOA (Time Difference Of Arrival) method that detects the position by combining the arrival time difference of the wave with the three-point surveying is known as one of the methods that can detect the position with the highest accuracy.

  The TDOA method is a method of measuring a wave arrival time difference in a plurality of base stations provided in a building where a communication terminal subject to position detection emits a wave, and a wave arrival time difference in a communication terminal when a base station emits a wave. There are two types of measurement methods. These methods are properly used depending on the application. However, for the reason that the configuration of the system is simple and the accuracy is easy to obtain, the former communication terminal that is the position detection target generates a wave.

  In this case, in order to measure the arrival time difference of one wave at a plurality of base stations, it is necessary to precisely synchronize the clocks between the base stations and synchronize the reception operation. For this reason, several methods for synchronizing operation synchronization between base stations have been proposed.

  For example, a method has been proposed in which a reference signal generated from one signal generator is simultaneously transmitted to each base station via an optical fiber or the like, and each base station performs a base station operation in synchronization with the received reference signal clock. (For example, refer to Patent Document 1). Further, for example, a method has been proposed in which a delay error and a measurement time error due to a distance difference between base stations are evaluated and stored in advance, and the position detection result is corrected (for example, see Patent Document 2).

FIG. 14 is a schematic diagram showing a schematic configuration of a conventional position detection system described in Patent Document 1. As shown in FIG. A position detection system 1400 shown in FIG. 14 includes a reference station 1401 and a plurality of base stations 1402 to 1404 connected to the reference station 1401 and optical fibers 1405 in order to detect the position of the communication terminal 1406. The reference station 1401 transmits a reference signal 1407 to each base station via the optical fiber 1405, and each base station receives the reference signal 1407 and synchronizes the operation timing between the base stations. The communication terminal 1406 transmits a measurement signal for position detection. The time at which the measurement signal reaches each base station depends on the distance between the communication terminal 1406 and each base station. Differences occur. From this arrival time difference, the position of the communication terminal 1406 is calculated by the TDOA method. In each base station, in order to accurately measure the arrival time of the measurement signal, the operation timing is synchronized with the reference signal 1407, thereby time adjustment of the measurement start time in each base station is performed.
JP 2004-112558 A JP 2004-221704 A

  However, in the conventional configuration described in Patent Document 1, due to the difference in the distance from the reference station to each base station and the characteristic variation of the components of the PLL (Phase Locked Loop) circuit that regenerates the clock from the reference signal in each base station. There is a problem that an error occurs in the measurement start time between the base stations, and the processing cost is required for calibration of the position detection accuracy. In addition, it is necessary to lay communication equipment such as an optical fiber between the base station and each base station, and there is a problem of increasing the cost of the entire system because it takes a cost to construct a communication infrastructure.

  Further, in the conventional configuration described in Patent Document 2, it is necessary to acquire a measurement error prior to position detection, and there is a problem that the cost of system hardware and the time cost of error measurement are required for the processing, Since the position detection result is indirectly corrected by the measurement error, there is a problem that the position detection accuracy is deteriorated.

  The present invention has been made to solve the above-described conventional problems, and provides a position detection system and a position detection method capable of synchronizing each base station with a simple configuration and with high accuracy. Objective.

  The position detection system according to the present invention includes a reference station, a communication terminal, a plurality of base stations, and a position calculator. The reference station is disposed equidistant from the plurality of base stations and includes a reference signal transmission unit that transmits a reference signal. The communication terminal includes a first reference signal receiving unit that receives a reference signal, and a measurement signal transmitting unit that transmits a measurement signal after receiving the reference signal. Each of the plurality of base stations includes a second reference signal receiving unit that receives the reference signal, a measurement signal receiving unit that receives the measurement signal after receiving the reference signal, and until receiving the measurement signal after receiving the reference signal And a time data signal transmitter for transmitting the time data signal. The position calculator includes a time data signal receiving unit that receives a time data signal from each of a plurality of base stations, and a calculation unit that calculates the position of the communication terminal based on the time data signal.

  A position detection method according to the present invention is a position detection method for detecting the position of a communication terminal, the step of transmitting a reference signal from a reference station arranged equidistant from a plurality of base stations, Receiving a reference signal after receiving the reference signal, receiving a reference signal by a plurality of base stations, receiving a measurement signal after receiving the reference signal, and receiving the reference signal Generating a time data signal by measuring the time from when the measurement signal is received, transmitting a plurality of time data signals from a plurality of base stations, and a plurality of time data signals by a position calculator Receiving, and calculating a position of the communication terminal based on the received plurality of time data signals.

  According to these configurations, the reference station transmits the reference signal, and each base station and the communication terminal receive the reference signal. The communication terminal transmits the measurement signal after receiving the reference signal transmitted by the reference station. After receiving the reference signal transmitted from the reference station, each base station receives the measurement signal transmitted from the communication terminal, measures the time interval between both signals, and generates a time data signal. Each base station then transmits a time data signal to the position calculator. The position calculator calculates the arrival time difference of the measurement signal at each base station based on the time data signal transmitted from each base station, and calculates the position of the communication terminal by, for example, a three-point survey method.

  Specifically, when the base station receives the reference signal from the reference station, it starts timekeeping by the timekeeping unit provided in the base station, and when the measurement signal from the communication terminal is received, timekeeping by the timekeeping unit is stopped Thus, the time interval from the reception of the reference signal to the reception of the measurement signal can be measured. Further, since the reference station is arranged at an equal distance from each base station, the reference signal transmitted from the reference station is received at each base station at the same time. That is, since the timekeeping by the timekeeping unit in each base station is executed at the same time, each timekeeping unit in each base station keeps the same time. Therefore, it is possible to regard the time at which the time is stopped by the time measuring unit in each base station as the arrival time difference of the measurement signal between the base stations. With these operations, synchronization between base stations can be performed with a simple configuration and high accuracy.

  In the position detection system, the reference signal transmission unit of the reference station multiplexes a terminal code that is a terminal identification code that identifies a communication terminal that is a position detection target and a reference code that is a signal type code representing the reference signal. First data multiplexing means for generating a reference signal, and the first reference signal receiving unit of the communication terminal comprises first data separation means for separating the reference code and the terminal code from the reference signal, and the communication terminal The measurement signal transmission unit transmits a measurement signal when the terminal code separated by the first data separation unit matches its own terminal code, and the second reference signal reception units of the plurality of base stations A second data separation means for separating the reference code and the terminal code from the reference signal, and the time data signal transmitters of the plurality of base stations are terminals separated by the second data separation means And a second data multiplexing means for generating a time data signal by multiplexing a time code which is a signal type code representing the time data signal, and the time data signal receiving unit of the position calculator A third data separation unit for separating the time code and the terminal code from the signal, and the calculation unit of the position calculator determines the position of the communication terminal based on the time code and the terminal code separated by the third data separation unit. It is preferable to calculate.

  According to this configuration, since the reference station multiplexes the reference code and the terminal code and transmits it as a reference signal, the communication terminal that has received the reference signal including the terminal code matches with its own terminal code. Only the measurement signal can be transmitted. Therefore, even when there are a plurality of communication terminals, the position of a specific communication terminal can be detected. Further, the base station that has received the reference signal including the terminal code transmits the time data signal obtained as a result of measuring the arrival time of the subsequent measurement signal to the position calculator in association with the terminal code. The device can calculate and output the position of a specific communication terminal.

  In the above position detection system, the measurement signal transmission unit of the communication terminal multiplexes the terminal code separated by the first data separation means and the measurement code which is a signal type code representing the measurement signal, thereby measuring the measurement signal. Preferably, the measurement signal receiving units of the plurality of base stations include fourth data separation means for separating the measurement code and the terminal code from the measurement signal.

  According to this configuration, since the communication terminal transmits the measurement signal including the terminal code, the base station that has received the measurement signal including the terminal code can obtain the time data signal obtained from the measurement result of the arrival time of the measurement signal. Can be transmitted to the position calculator in association with the terminal code, and the position calculator can calculate and output the position of a particular communication terminal.

  In the above position detection system, the communication terminal further includes a first communication unit that transmits a first measurement start signal indicating a transmission request for the reference signal, and the reference station receives the first measurement start signal. It is preferable to further include a second communication unit, and when the second communication unit receives the first measurement start signal, the reference signal transmission unit preferably transmits the reference signal.

  According to this configuration, the communication terminal can request the reference station to transmit a reference signal, and the communication terminal can start the operation of the position detection system at an arbitrary time. Therefore, it is possible to cope with an application in which the communication terminal is an initiator of the position detection operation.

  In the above position detection system, the plurality of base stations further include a third communication unit that transmits a second measurement start signal indicating a transmission request for the reference signal, and the reference station transmits the second measurement start signal. It is preferable to further include a second communication unit to receive, and when the second communication unit receives the second measurement start signal, the reference signal transmission unit preferably transmits the reference signal.

  According to this configuration, the base station can request the reference station to transmit a reference signal, and the base station can start the operation of the position detection system at an arbitrary time. Therefore, it is possible to cope with an application in which the base station is an initiator of the position detection operation.

  In the above position detection system, the position calculator further includes a fourth communication unit that transmits a third measurement start signal indicating a transmission request for the reference signal, and the reference station receives the third measurement start signal. It is preferable to further include a second communication unit that transmits the reference signal to the reference signal transmission unit when the second communication unit receives the third measurement start signal.

  According to this configuration, the position calculator can request the reference station to transmit a reference signal, and the position calculator can start the operation of the position detection system at an arbitrary time. Therefore, the position calculator can cope with an application that becomes an initiator of the position detection operation.

  In the position detection system, the first to third measurement start signals preferably include a terminal code.

  According to this configuration, when the initiator starts the position detection operation, the terminal code of the communication terminal targeted for position detection can be included in the measurement start signal, so that the communication terminal can be individually specified. Therefore, it is possible to deal with an application that detects the position of a specific communication terminal from among a plurality of communication terminals.

  The present invention will be described with reference to the best mode for carrying out the invention described below and the drawings. However, this is for the purpose of illustration, and the present invention is intended to be limited thereto. is not.

  According to the present invention, the position of the communication terminal is calculated based on the arrival time from the reference signal received at each base station to the measurement signal received at each base station, but the reference stations arranged at equal distances from each base station Since the base signal transmitted from the base station is received at the same time by each base station, the time measurement operation of the arrival time at each base station can be started at the same time. Therefore, accurate synchronization between base stations can be realized with a simple configuration, and highly accurate position detection can be performed at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing a schematic configuration of a position detection system according to a first embodiment of the present invention.

  In FIG. 1, the position detection system 100 includes a reference station 101, base stations 102, 103, and 104, a position calculator 105, and a communication terminal 106. The reference station 101 is arranged at an equal distance (L) from the base stations 102 to 104. The function of the position detection system 100 is to detect the position of the communication terminal 106. Note that the position detection method in the present embodiment uses the arrival time difference depending on the transmission distance of the wave, and the wave transmitted from the communication terminal 106 is triggered by the signal transmitted from the reference station 101 as a base station 102. The position of the communication terminal 106 is calculated by counting the arrival time differences of the waves received at ˜104. Here, as an example, using the three base stations 102 to 104, the position of the communication terminal 106 is calculated by a three-point survey method using the three base stations as survey points. At this time, if the coordinates of the base stations 102 to 104, the arrival times of the waves at the base stations 102 to 104, and the speed of the waves are known, the coordinates of the communication terminal 106 that is transmitting the waves can be obtained. . Therefore, an accurate position detection result can be obtained by accurately measuring the wave arrival time at each of the base stations 102 to 104 which is a variable element.

  The wave used for position detection and the communication medium for communication between each component can be any of radio waves, sound waves (including ultrasonic waves), light waves, elastic waves, etc. The case is illustrated and described as an example.

  FIG. 2 is a schematic diagram for explaining the operation of the position detection system according to the first embodiment of the present invention. In FIG. 2, the same components as those shown in FIG.

  In FIG. 2, the reference station 101 transmits a reference signal 110 to the surroundings, and the communication terminal 106 and the base stations 102 to 104 receive the reference signal 110. At this time, since the positional relationship between the reference station 101 and the communication terminal 106 is arbitrary, the time at which the communication terminal 106 receives the reference signal 110 depends on the positional relationship. Furthermore, since the reference station 101 is located at an equal distance from the base stations 102 to 104, the time at which the base stations 102 to 104 receive the reference signal 110 is the same time at each base station. In addition, since the base stations 102 to 104 are arranged at the corners of the measurement area of the position detection system 100, the reception time of the reference signal 110 at the communication terminal 106 located in the area is the reference signal 110 at the base stations 102 to 104. It becomes earlier than or equal to the reception time of.

  The communication terminal 106 transmits the measurement signal 120 following the reception of the reference signal 110. Although the base stations 102 to 104 receive the measurement signal 120, the positional relationship between the communication terminal 106 and the base stations 102 to 104 is arbitrary, so that each time when each base station 102 to 104 receives the measurement signal 120 is , Depending on the positional relationship between the communication terminal 106 and each of the base stations 102 to 104. The base stations 102 to 104 measure time from the time when the reference signal 110 is received, and time until the time when the measurement signal 120 is received.

  Since the reception time of the reference signal 110 in each of the base stations 102 to 104 is the same time, the time measurement start time is the same time, and the length of time is compared with each other according to the time at which the measurement signal 120 is received in each base station. be able to. That is, the arrival time difference of the measurement signal 120 at each base station 102 to 104 can be obtained by a simple difference in the reception time of the measurement signal 120 at each base station.

  The base stations 102 to 104 transmit the reception time of the measurement signal 120 to the position calculator 105 as time data signals 130, 131, and 132. The position calculator 105 calculates the arrival time difference of the measurement signal 120 at each of the base stations 102 to 104 from the received time data signals 130 to 132, and the calculated arrival time difference and the known coordinates of the base stations 102 to 104 and The coordinates of the communication terminal 106 are calculated and output using the wave velocity.

  FIG. 3 is a block diagram showing an internal configuration of the reference station according to the first embodiment of the present invention.

  In FIG. 3, the reference station 300 includes a control unit 301 and a reference signal transmission unit 302. The control unit 301 controls each unit in the reference station 300, outputs a reference code D30 serving as the original data of the reference signal, and a terminal code D31 that identifies a communication terminal that is a position detection target, and a reference signal transmission unit 302 Forms a reference signal and outputs it as a radio wave.

  The reference signal transmission unit 302 includes a multiplexing unit 303 (first data multiplexing unit), a modulation unit 304, and a transmission unit 305. The multiplexing unit 303 multiplexes the reference code D30 generated by the control unit 301 and the terminal code D31 to generate packet data, the modulation unit 304 modulates the packet data to generate a modulated signal, and the transmission unit 305 frequency-converts and amplifies the modulated signal and transmits it as a reference signal from the antenna.

  FIG. 4 is a block diagram showing an internal configuration of the communication terminal according to the first embodiment of the present invention.

  In FIG. 4, the communication terminal 400 includes a control unit 401, a reference signal receiving unit 402, a measurement signal transmitting unit 403, and a switching unit 410. The control unit 401 controls each unit in the communication terminal 400 and inputs / outputs transmission / reception signals. The switching unit 410 switches between a reception signal from the antenna and a transmission signal to the antenna according to an instruction from the control unit 401.

  The reference signal reception unit 402 includes a reception unit 404, a demodulation unit 405, and a separation unit 406 (first data separation unit). The receiving unit 404 reproduces the modulated signal by performing high frequency amplification and frequency conversion on the reference signal input from the antenna via the switching unit 410, and the demodulating unit 405 regenerates the packet data by demodulating the modulated signal. 406 separates and reproduces the reference code D40 and the terminal code D41 from the packet data. The reproduced reference code D40 and terminal code D41 are input to the control unit 401.

  The measurement signal transmission unit 403 includes a multiplexing unit 407 (third data multiplexing unit), a modulation unit 408, and a transmission unit 409. The multiplexing unit 407 multiplexes the reference code D42 and the terminal code D43 generated by the control unit 401 to generate packet data, the modulation unit 408 modulates the packet data to generate a modulated signal, and the transmission unit 409 Then, the modulation signal is subjected to frequency conversion and high frequency amplification, and is transmitted as a measurement signal from the antenna via the switching unit 410.

  FIG. 5 is a block diagram showing an internal configuration of the base station according to the first embodiment of the present invention.

  In FIG. 5, the base station 500 includes a control unit 501, a reference signal receiving unit 502, a measurement signal receiving unit 503, a time data signal transmitting unit 504, a time measuring unit 505, and a switching unit 515. The control unit 501 controls each unit in the base station 500 and inputs / outputs transmission / reception signals. The switching unit 515 performs switching between a reception signal from the antenna and a transmission signal to the antenna according to an instruction from the control unit 501.

  The reference signal reception unit 502 includes a reception unit 506, a demodulation unit 507, and a separation unit 508 (second data separation unit). The receiving unit 506 reproduces the modulated signal by performing high frequency amplification and frequency conversion on the reference signal input from the antenna via the switching unit 515, and the demodulating unit 507 demodulates the modulated signal to reproduce packet data, and the separating unit 508 separates and reproduces the reference code D50 and the terminal code D51 from the packet data. The reproduced reference code D50 and terminal code D51 are input to the control unit 501.

  The measurement signal reception unit 503 includes a reception unit 509, a demodulation unit 510, and a separation unit 511 (fourth data separation unit). The receiving unit 509 performs high frequency amplification and frequency conversion on the measurement signal input from the antenna via the switching unit 515 to reproduce the modulation signal, and the demodulation unit 510 demodulates the modulation signal to reproduce packet data, and the separation unit 511 separates and reproduces the measurement code D52 and the terminal code D53 from the packet data. The reproduced measurement code D52 and terminal code D53 are input to the control unit 501.

  The time data signal transmission unit 504 includes a multiplexing unit 512 (second data multiplexing unit), a modulation unit 513, and a transmission unit 514. The multiplexing unit 512 generates packet data by multiplexing the time code D54 generated by the control unit 501, the base code D55, and the terminal code D56, and the modulation unit 513 generates a modulated signal by modulating the packet data. Then, the transmission unit 514 performs frequency conversion and high-frequency amplification on the modulated signal and transmits the measurement signal as a measurement signal from the antenna via the switching unit 515.

  The timer unit 505 is composed of, for example, a self-running clock counter with a built-in crystal oscillator. When the reset signal S50 from the control unit 501 is asserted, the counter value is reset to zero, and the reset signal S50 is negated. And the counter value is output to the control unit 501 as a time measurement result S51.

  FIG. 6 is a block diagram showing an internal configuration of the position calculator according to the first embodiment of the present invention.

  In FIG. 6, the position calculator 600 includes a control unit 601, a time data signal reception unit 602, a calculation unit 603, and an input / output unit 607. The control unit 601 controls each unit in the position calculator 600, and performs input of received signals, position calculation of a communication terminal, and input / output control with a host control system including a user.

  The time data signal reception unit 602 includes a reception unit 604, a demodulation unit 605, and a separation unit 606 (third data separation unit). The receiving unit 604 amplifies and frequency converts the time data signal input from the antenna to reproduce the modulation signal, the demodulation unit 605 demodulates the modulation signal to reproduce packet data, and the separation unit 606 The time code D60, base code D61, and terminal code D62 are separated from the data and reproduced. The reproduced time code D60, base code D61, and terminal code D62 are input to the control unit 601.

  The calculation unit 603 is a calculation unit that executes a position calculation algorithm including numerical calculation for position calculation. The calculation unit 603 receives time data for position calculation and necessary parameters from the control unit 601, and after position calculation processing, position calculation is performed. The result is returned to the control unit 601.

  The input / output unit 607 receives input control commands from the host control system and the user, and performs input processing to pass to the control unit 601 and output processing to pass the position detection result from the control unit 601 to the host control system and user.

  FIG. 7A is a format diagram of a reference signal in the first embodiment of the present invention.

  In FIG. 7A, the reference signal 700 is configured as a data packet, and includes a synchronization code 701, a signal type code 702, a terminal code 703, and an error correction code 704.

  The synchronization code 701 is a data string indicating the packet head of the reference signal 700, and is composed of a preamble bit for pulling in the PLL on the receiving side and a synchronization code indicating the byte alignment head of the data.

  The signal type code 702 is an identification code indicating the type of the data packet (a reference signal in FIG. 7A, which is a reference signal, a measurement signal, or a time data signal).

  The terminal code 703 is an identification code unique to the communication terminal for specifying the communication terminal that is the position detection target.

  The error correction code 704 is a check code for detecting and correcting a transmission error of the data packet, such as a Reed-Solomon code.

  FIG. 7B is a format diagram of a measurement signal according to the first embodiment of the present invention.

  In FIG. 7B, the measurement signal 710 is configured as a data packet, and includes a synchronization code 711, a signal type code 712, a terminal code 713, and an error correction code 714. The function of each component is the same as that of the reference signal 700.

  FIG. 7C is a format diagram of a time data signal according to the first embodiment of the present invention.

  In FIG. 7C, the time data signal 720 is configured as a data packet, and includes a synchronization code 721, a signal type code 722, a base code 723, a terminal code 724, and an error correction code 725. Base code 723 is an identification code unique to the base station for identifying the base station that transmitted time data signal 720. The functions of the other components are the same as those of the reference signal 700.

  FIG. 8 is an operation timing chart of the position detection system according to the first embodiment of the present invention.

  In FIG. 8, the transmission / reception timing of each component of the reference station 101, the communication terminal 106, the base stations 102 to 104, and the position calculator 105 is shown with the horizontal axis as the time axis.

  The reference station 101 transmits a reference signal S800 (time T0). The communication terminal 106 receives the reference signal S800 (time T1). Thereafter, the base stations 102 to 104 receive the reference signal S800 (time T2). Here, since the time T1 depends on the distance between the reference station 101 and the communication terminal 106, the time relationship between the time T1 and the time T2 can be any relationship of T1 <T2, T1 = T2, and T1> T2. However, since the reference station 101 is equidistant from the base stations 102 to 104, the time at which the base stations 102 to 104 receive the reference signal S800 transmitted from the reference station 101 is the same time (time T2). is there.

  When receiving the reference signal S800 (time T1), the communication terminal 106 transmits the measurement signal S810 after a predetermined time Tm (time T3). The base station 102 receives the measurement signal S810 after time Tm + Δt1 including a delay depending on the distance to the communication terminal 106 (time T4). Here, the time Δt1 is a radio wave transmission time from the communication terminal 106 to the base station 102.

  The base station 103 receives the measurement signal S810 after time Tm + Δt2 including a delay depending on the distance to the communication terminal 106 (time T5). Here, the time Δt2 is a radio wave transmission time from the communication terminal 106 to the base station 103.

  The base station 104 receives the measurement signal S810 after time Tm + Δt3 including a delay depending on the distance from the communication terminal 106 (time T6). Here, the time Δt3 is a radio wave transmission time from the communication terminal 106 to the base station 104.

  At this time, the time relationship between Δt1 to Δt3 depends on the positional relationship between the communication terminal 106 and each base station 102 to 104, and the time relationship between Δt1 to Δt3 shown in FIG. This is an example based on the positional relationship with the base stations 102 to 106.

  The base station 102 starts the time measuring operation at the time measuring unit (corresponding to the time measuring unit 505 in FIG. 5) from the time T2 when the reference signal S800 is received, and stops the time measuring operation at the time T4 when the measurement signal S810 is received. Thus, the time Tm + Δt1 (corresponding to the time measurement result S51 in FIG. 5) is obtained.

  The base station 103 starts the time measuring operation at the time measuring unit from the time T2 when the reference signal S800 is received, and stops the time measuring operation at the time T5 when the measurement signal S810 is received, thereby obtaining the time Tm + Δt2.

  The base station 104 starts the time measuring operation at the time measuring unit from the time T2 at which the reference signal S800 is received, and stops the time measuring operation at the time T6 at which the measurement signal S810 is received to obtain the time Tm + Δt3.

  Next, the base station 102 determines the time from the time code (corresponding to the time code D54 in FIG. 5) indicating the measured Tm + Δt1, the base code unique to the base station 102 (corresponding to the base code D55 in FIG. 5), the terminal code, and the like. Data is generated and a time data signal S820 is transmitted. The position calculator 105 receives the time data signal S820, extracts the base code and the time data, and stores the time data in the base station 102 as a part of the position calculation data.

  The base station 103 generates time data from a time code indicating the measured Tm + Δt2, a base code unique to the base station 103, a terminal code, and the like, and transmits a time data signal S821. The position calculator 105 receives the time data signal S821, extracts the base code and the time data, and stores the time data in the base station 103 as a part of the position calculation data.

  The base station 104 generates time data from the time code indicating the measured Tm + Δt3, the base code unique to the base station 104, the terminal code, and the like, and transmits the time data signal S822. The position calculator 105 receives the time data signal S822, extracts the base code and time data, and stores the time data in the base station 104 as part of the position calculation data.

  The position calculator 105 calculates the position of the communication terminal 106 by the following calculation.

  The spatial coordinate P is expressed as (x, y, z), the coordinate P0 of the communication terminal is P0 = (x0, y0, z0), the coordinate P1 of the base station 102 is P1 = (x1, y1, z1), The coordinate P2 of the base station 103 is P2 = (x2, y2, z2), and the coordinate P3 of the base station 104 is P3 = (x3, y3, z3).

  Here, the arrival time of the measurement signal S810 to the base station 102 is T4, the arrival time of the measurement signal S810 to the base station 103 is T5, and the arrival time of the measurement signal S810 to the base station 104 is T6. If the speed is v, the position of the communication terminal is a solution P0 of the following simultaneous equations.

| P0-P2 |-| P0-P1 | = v (T5-T4)
| P0-P3 |-| P0-P1 | = v (T6-T4)
As described above, according to the configuration of the present embodiment, the reference station transmits the reference signal, and each base station and the communication terminal receive the reference signal. The communication terminal transmits the measurement signal after receiving the reference signal transmitted by the reference station. After receiving the reference signal transmitted from the reference station, each base station receives the measurement signal transmitted from the communication terminal, measures the time interval between both signals, and generates a time data signal. Each base station then transmits a time data signal to the position calculator. The position calculator calculates the arrival time difference of the measurement signal at each base station based on the time data signal transmitted from each base station, and calculates the position of the communication terminal by the three-point survey method.

  Specifically, when the base station receives the reference signal from the reference station, it starts timekeeping by the timekeeping unit provided in the base station, and when the measurement signal from the communication terminal is received, timekeeping by the timekeeping unit is stopped Thus, the time interval from the reception of the reference signal to the reception of the measurement signal can be measured. Further, since the reference station is arranged at an equal distance from each base station, the reference signal transmitted from the reference station is received at each base station at the same time. That is, since the timekeeping by the timekeeping unit in each base station is executed at the same time, each timekeeping unit in each base station keeps the same time. Therefore, it is possible to regard the time at which the time is stopped by the time measuring unit in each base station as the arrival time difference of the measurement signal between the base stations. With these operations, synchronization between base stations can be performed with a simple configuration and high accuracy.

  Since the reference station 300 (FIG. 3) transmits the reference signal including the terminal code D31 (FIG. 3), the communication terminal 400 (FIG. 4) that has received the reference signal including the terminal code 31 The terminal code D41 (FIG. 4) having the same content as the code D31 is reproduced, and the measurement signal can be transmitted only when it matches the terminal code of its own. Therefore, even if there are a plurality of communication terminals, the position of a specific communication terminal can be detected.

  Further, the base station 500 (FIG. 5) that has received the reference signal including the terminal code D31 uses the time code D54 (FIG. 5) obtained as a result of measuring the arrival time of the subsequent measurement signal as the base code D55. Is transmitted to the position calculator 600 (FIG. 6) in association with the terminal code D56 (FIG. 5) having the same contents as the terminal code D31, so that the position calculator 600 reproduces the reproduced time code D60, base code D61, and Based on the terminal code D62, the position of the specific communication terminal 400 can be calculated and output.

  Also, since the communication terminal 400 transmits the measurement signal including the terminal code D43 that is its own terminal code, the base station 500 that has received the measurement signal including the terminal code D43 determines the arrival time of the measurement signal. The time code D54 obtained as a result of the measurement can be transmitted to the position calculator 600 in association with the base code D55, the terminal code D56 having the same contents as the terminal code D43, and the base code D55. Based on the reproduced time code D60, base code D61, and terminal code D62, the position of a specific communication terminal 400 can be calculated and output.

(Second Embodiment)
FIG. 9 is a block diagram showing an internal configuration of the reference station according to the second embodiment of the present invention. In FIG. 9, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

  9, the reference station 900 includes a communication unit 902 (second communication unit) in addition to the configuration shown in FIG. Note that the control unit 901 has a function of transmitting and receiving communication data D90 to and from the communication unit 902 in addition to the function of the control unit 301 shown in FIG. The communication unit 902 includes a modulation / demodulation unit 903 and a transmission / reception unit 904. The modulation / demodulation unit 903 modulates / demodulates communication data D90 transmitted / received to / from the control unit 901, and the transmission / reception unit 904 transmits a communication signal (first measurement start). A signal, a second measurement start signal (described in the third embodiment), and a third measurement start signal (described in the fourth embodiment) are transmitted and received via the antenna.

  FIG. 10 is a block diagram showing an internal configuration of a communication terminal according to the second embodiment of the present invention. In FIG. 10, the same components as those shown in FIG.

  10, the communication terminal 1000 includes a communication unit 1002 (first communication unit) in addition to the configuration shown in FIG. Note that the control unit 1001 has a function of transmitting / receiving the communication data D100 to / from the communication unit 1002, in addition to the function of the control unit 401 shown in FIG. The communication unit 1002 includes a modulation / demodulation unit 1003 and a transmission / reception unit 1004. The modulation / demodulation unit 1003 modulates / demodulates communication data D100 transmitted / received to / from the control unit 1001, and the transmission / reception unit 1004 transmits a communication signal (first measurement start). Signal) via the antenna.

  According to this configuration, when it is desired to issue a reference signal transmission request from the communication terminal 1000 to the reference station 900, that is, to perform a position detection operation of the communication terminal, the communication terminal 1000 uses the first measurement start signal as a communication signal. Is transmitted to the reference station 900, the operation of the position detection system can be started at an arbitrary time of the communication terminal 1000. Therefore, the communication terminal 1000 can cope with an application that becomes an initiator of the position detection operation.

  In this configuration, the control unit 1001 may generate the communication data D100 including the terminal code D43 of the position detection target communication terminal, thereby transmitting the first measurement start signal including the terminal code D43. it can. Further, the control unit 901 of the reference station 900 can separate the terminal code from the communication data D90, generate the terminal code D31, and multiplex it with the reference code D30. That is, the communication terminal that has requested the position detection operation can include its own terminal code in the reference signal. Thereby, a communication terminal can be individually designated with a reference signal. Therefore, it is possible to deal with an application that detects the position of a specific communication terminal from among a plurality of communication terminals.

  Although the antenna and the transmission / reception system for the communication signal have been illustrated and described as configurations independent of the other parts, the antenna and the transmission / reception system for the reference signal and the measurement signal may be shared.

(Third embodiment)
FIG. 11 is a block diagram showing an internal configuration of the base station according to the third embodiment of the present invention. In FIG. 11, the same components as those shown in FIG.

  In FIG. 11, a base station 1100 includes a communication unit 1102 (third communication unit) in addition to the configuration shown in FIG. Note that the control unit 1101 has a function of transmitting / receiving communication data D110 to / from the communication unit 1102 in addition to the function of the control unit 501 shown in FIG. The communication unit 1102 includes a modulation / demodulation unit 1103 and a transmission / reception unit 1104. The modulation / demodulation unit 1103 modulates / demodulates the communication data D110 transmitted / received to / from the control unit 1101, and the transmission / reception unit 1104 transmits a communication signal (second measurement start). Signal) via the antenna.

  According to this configuration, when it is desired to issue a reference signal transmission request from the base station 1100 to the reference station 900, that is, to perform a position detection operation of the communication terminal, the base station 1100 transmits the second measurement start signal as a communication signal. Is transmitted to the reference station 900, the operation of the position detection system can be started at an arbitrary time of the base station 1100. Therefore, the base station 1100 can cope with an application that becomes an initiator of the position detection operation.

  In this configuration, the control unit 1101 may generate the communication data D110 including the terminal code D56 of the position detection target communication terminal, thereby transmitting the second measurement start signal including the terminal code D56. it can. Further, the control unit 901 of the reference station 900 can separate the terminal code from the communication data D90, generate the terminal code D31, and multiplex it with the reference code D30. That is, the communication terminal can be individually specified by the reference signal. Therefore, it is possible to deal with an application that detects the position of a specific communication terminal from among a plurality of communication terminals.

  Although the antenna and the transmission / reception system for the communication signal have been illustrated and described as configurations independent of the other parts, the antenna and the transmission / reception system for the reference signal and the measurement signal may be shared.

(Fourth embodiment)
FIG. 12 is a block diagram showing the internal configuration of the position calculator in the fourth embodiment of the present invention. In FIG. 12, the same components as those shown in FIG.

  In FIG. 12, a position calculator 1200 includes a communication unit 1202 (fourth communication unit) in addition to the configuration shown in FIG. The communication unit 1202 includes a modulation / demodulation unit 1203 and a transmission / reception unit 1204. The modulation / demodulation unit 1203 modulates / demodulates the communication data D120 transmitted / received to / from the control unit 1201, and the transmission / reception unit 1204 transmits a communication signal (third measurement start). Signal) via the antenna.

  According to this configuration, when it is desired to issue a reference signal transmission request from the position calculator 1200 to the reference station 900, that is, to perform a position detection operation of the communication terminal, the position calculator 1200 uses the third measurement as a communication signal. By transmitting the start signal to the reference station 900, the position calculator 1200 can start operating the position detection system at an arbitrary time. Therefore, the position calculator 1200 can cope with an application that becomes an initiator of the position detection operation.

  Further, in this configuration, information specifying the position detection target communication terminal is input from the input / output unit 607 by the host control system or the user, and the control unit 1201 includes communication data including the terminal code D62 of the position detection target communication terminal. By generating D120, the third measurement start signal including the terminal code D62 can be transmitted. That is, the communication terminal can be individually specified by the reference signal. Therefore, it is possible to deal with an application that detects the position of a specific communication terminal from among a plurality of communication terminals.

  Although the antenna and the transmission / reception system for the communication signal have been illustrated and described as configurations independent of other parts, the antenna and the transmission / reception system for the reference signal, the measurement signal, and the time data signal may be shared.

(Fifth embodiment)
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. 8 in addition to FIG.

  FIG. 13: is a flowchart which shows each process in the position detection method concerning the 5th Embodiment of this invention.

  In FIG. 13, when a request for starting the position detection operation of the communication terminal 106 (first, second, or third measurement start signal) is issued from the communication terminal 106, the base stations 102 to 104, or the position calculator 105. The reference station 101 transmits a reference signal S800 (FIG. 8) at time T0 (step S1301). Since each base station is arranged around the position detection area, the communication terminal 106 in the position detection area receives the reference signal at time T1 prior to each base station (step S1302).

  The control unit 301 (FIG. 3) of the communication terminal 106 (300) determines whether or not the predetermined time Tm has elapsed since the communication terminal 106 received the reference signal (step S1303), and the predetermined time Tm has elapsed. If so (YES in step S1303), the communication terminal 106 transmits a measurement signal S810 at time T3 (step 1304).

  Since the reference stations are arranged equidistant from each base station, all base stations receive the reference signal at the same time T2 (step S1305). Each base station that has received the reference signal at the same time starts timing in the timing unit (505 in FIG. 5).

  Next, according to the position of the communication terminal 106, the base station 102 receives the measurement signal at time T4 and ends the time measurement in the time measurement unit, and the base station 103 receives the measurement signal at time T5 and measures the time in the time measurement unit. And the base station 104 receives the measurement signal at time T6 and ends the time measurement in the time measuring unit (step S1306).

  The base station 102 measures the time (T4−T2) from reception of the reference signal at time T2 to reception of the measurement signal at time T4 as Tm + Δt1, and the base station 103 starts from reception of the reference signal at time T2. The time until reception of the measurement signal at time T5 (T5-T2) is measured as Tm + Δt2, and the base station 104 measures the time from reception of the reference signal at time T2 to reception of the measurement signal at time T6 (T6- T2) is measured as Tm + Δt3 (step S1307).

  Next, the base station 102 transmits a time data signal S820 including a time code indicating the timed Tm + Δt1 to the position calculator 105, and the base station 103 calculates a position of the time data signal S821 including a time code indicating the timed Tm + Δt2. The base station 104 transmits a time data signal S822 including a time code indicating the measured Tm + Δt3 to the position calculator 105 (step S1308).

  When position calculator 105 receives all the time data signals S820, S821, and S822 (step S1309), it calculates the arrival time difference of the measurement signal at each base station based on all the time data signals, and determines the position of the communication terminal. Calculation is performed by the three-point survey method described in the first embodiment (step S1310).

  The position detection method of the present embodiment is also applied to a program for executing the position detection method in the reference station, base station, communication terminal, and position calculator, and a computer-readable recording medium storing the program. can do. A program recorded on the recording medium is executed on an apparatus including a CPU, a memory, and the like, so that a reference station, a base station, a communication terminal, and a position calculator can be configured.

  The position detection system and position detection method according to the present invention have the advantage that the position of the communication terminal can be detected with high accuracy at low cost. It can be applied to a monitoring system for weak people such as the elderly and life assist robot control, and can also be applied to an article management system, a facility management system, etc. for business use.

The schematic diagram which shows schematic structure of the position detection system concerning the 1st Embodiment of this invention. The schematic diagram for demonstrating operation | movement of the position detection system concerning the 1st Embodiment of this invention. The block diagram which shows the internal structure of the reference station in the 1st Embodiment of this invention. The block diagram which shows the internal structure of the communication terminal in the 1st Embodiment of this invention. The block diagram which shows the internal structure of the base station in the 1st Embodiment of this invention. The block diagram which shows the internal structure of the position calculator in the 1st Embodiment of this invention. The format figure of the reference signal (A) in the 1st Embodiment of this invention, the measurement signal (B), and the time data signal (C). The operation | movement timing diagram of the position detection system concerning the 1st Embodiment of this invention. The block diagram which shows the internal structure of the reference station in the 2nd Embodiment of this invention. The block diagram which shows the internal structure of the communication terminal in the 2nd Embodiment of this invention. The block diagram which shows the internal structure of the base station in the 3rd Embodiment of this invention. The block diagram which shows the internal structure of the position calculator in the 4th Embodiment of this invention. The flowchart which shows each process in the position detection method concerning the 5th Embodiment of this invention. The schematic diagram which shows schematic structure of the conventional position detection system described in patent document 1. FIG.

Explanation of symbols

100 Position detection system 101, 300, 900 Reference station 102, 103, 104, 500, 1100 Base station 105, 600, 1200 Position calculator 106, 400, 1000 Communication terminal 110 Reference signal 120 Measurement signal 130, 131, 132 Time data signal 302 Reference signal transmission unit of reference station 300 303 Multiplexing unit (first data multiplexing unit)
402 Reference signal reception unit of communication terminal 400 403 Measurement signal transmission unit of communication terminal 400 406 Separation unit (first data separation unit)
407 Multiplexer (third data multiplexing means)
502 Reference signal reception unit of base station 500 503 Measurement signal reception unit of base station 500 504 Time data transmission unit of base station 500 508 Separation unit (second data separation unit)
511 Separation unit (fourth data separation means)
512 Multiplexer (second data multiplexing means)
602 Time data reception unit of position calculator 600 606 separation unit (third data separation unit)
902 Communication unit (second communication unit)
1002 Communication unit (first communication unit)
1102 Communication unit (third communication unit)
1202 Communication unit (fourth communication unit)

Claims (10)

A reference station having a reference signal transmitter for transmitting the reference signal;
A communication terminal having a first reference signal receiving unit that receives the reference signal, and a measurement signal transmitting unit that transmits a measurement signal after receiving the reference signal;
A second reference signal receiving unit for receiving the reference signal; a measurement signal receiving unit for receiving the measurement signal after receiving the reference signal; and a time from receiving the reference signal to receiving the measurement signal. A time measuring unit that generates a time data signal by measuring, and a time data signal transmitting unit that transmits the time data signal, respectively, and a plurality of base stations each having an equal distance from the reference station,
A time data signal receiving unit for receiving the time data signal from each of the plurality of base stations, and a position calculator having a calculating unit for calculating the position of the communication terminal based on the time data signal. Position detection system. The reference signal transmission unit of the reference station multiplexes a terminal code that is a terminal identification code that identifies a communication terminal that is a position detection target and a reference code that is a signal type code representing a reference signal to generate the reference signal. 1 data multiplexing means,
The first reference signal receiving unit of the communication terminal includes first data separation means for separating a reference code and a terminal code from the reference signal, and the measurement signal transmission unit of the communication terminal includes the first data separation When the terminal code separated by the means matches with its own terminal code, the measurement signal is transmitted,
The second reference signal receiving unit of the plurality of base stations includes second data separation means for separating a reference code and a terminal code from the reference signal, and the time data signal transmission unit of the plurality of base stations includes the A second data multiplexing means for multiplexing the terminal code separated by the second data separation means and a time code that is a signal type code representing the time data signal to generate the time data signal;
The time data signal receiving unit of the position calculator includes third data separation means for separating a time code and a terminal code from the time data signal, and the calculation unit of the position calculator includes the third data separation means. The position detection system according to claim 1, wherein the position of the communication terminal is calculated based on the time code and the terminal code separated by. The measurement signal transmission unit of the communication terminal generates a measurement signal by multiplexing the terminal code separated by the first data separation unit and a measurement code that is a signal type code representing the measurement signal. Data multiplexing means,
The position detection system according to claim 2, wherein the measurement signal receiving units of the plurality of base stations include fourth data separation means for separating a measurement code and a terminal code from the measurement signal. The communication terminal further includes a first communication unit that transmits a first measurement start signal indicating a transmission request for the reference signal,
The reference station further includes a second communication unit that receives the first measurement start signal. When the second communication unit receives the first measurement start signal, the reference station transmits the reference signal to the reference signal transmission unit. 4. The position detection system according to claim 1, wherein a signal is transmitted. The plurality of base stations further includes a third communication unit that transmits a second measurement start signal indicating a transmission request for the reference signal,
The reference station further includes a second communication unit that receives the second measurement start signal. When the second communication start unit receives the second measurement start signal, the reference station transmits the reference signal to the reference signal transmission unit. 4. The position detection system according to claim 1, wherein a signal is transmitted. The position calculator further includes a fourth communication unit that transmits a third measurement start signal indicating a transmission request for the reference signal,
The reference station further includes a second communication unit that receives the third measurement start signal. When the second communication unit receives the third measurement start signal, the reference station transmits the reference signal to the reference signal transmission unit. 4. The position detection system according to claim 1, wherein a signal is transmitted.   The position detection system according to claim 4, wherein the terminal code is included in the first measurement start signal.   The position detection system according to claim 5, wherein the terminal code is included in the second measurement start signal.   The position detection system according to claim 6, wherein the terminal code is included in the third measurement start signal. A position detection method for detecting the position of a communication terminal,
Transmitting a reference signal from a reference station located equidistant from a plurality of base stations;
Receiving the reference signal by the communication terminal;
Transmitting a measurement signal after receiving the reference signal;
Receiving the reference signal by the plurality of base stations;
Receiving the measurement signal after receiving the reference signal;
Measuring a time from receiving the reference signal to receiving the measurement signal to generate a time data signal;
Transmitting a plurality of time data signals from the plurality of base stations;
Receiving the plurality of temporal data signals by a position calculator;
Calculating the position of the communication terminal based on a plurality of received time data signals.

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