JP2006118888A - Position detecting system, position detection method for position detecting system, position detection communications device, and the communications device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection system, capable of detecting a position of the second communications device, a position detection method for the position detection system, a position detection communications device, and a communications device. <P>SOLUTION: In this position detection system for detecting the position of the second communications device, based on a plurality of distances between a plurality of the first communications devices and the second communications device, each of the plurality of first communications devices is provided with the first transmission part for transmitting a distance calculating signal for calculating the distance with respect to the second communications device; a detection part for detecting the phase difference between the distance calculating signal when transmitted by reception of a signal in response to the distance calculating signal, and a signal in response to the distance calculating signal when received; and a calculation part for calculating the distance with respect to the second communications device, based on the phase difference, and the second communications device has a position detecting part provided with the second transmission part for transmitting a signal in response to the distance calculating signal, and for detecting the position of the second communications device, based on the plurality of distances calculated in a plurality of calculation parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a position detection system, a position detection method for a position detection system, a position detection communication device, and a communication device.

  In recent years, as communication devices that communicate with each other to execute predetermined processing, for example, an in-vehicle device and a portable device in a vehicle equipped with a function capable of starting and stopping an engine without using a key (hereinafter referred to as a smart ignition function). There is a machine.

  Hereinafter, communication between an in-vehicle device and a portable device in an automobile equipped with a smart ignition function will be described in detail. For example, the in-vehicle device is provided inside the automobile, and the portable device is possessed by the driver of the automobile. Then, the driver unlocks the door of the car and gets into the car.

  When receiving a signal based on the fact that the door of the automobile is closed, the control unit provided separately inside the automobile transmits a signal for confirming whether or not the engine start is permitted to the in-vehicle device. When the in-vehicle device receives the signal from the control unit, the in-vehicle device transmits a signal (hereinafter referred to as a signal A) for confirming whether the portable device is in the car. When the portable device is in the automobile, the portable device receives the signal A from the in-vehicle device and transmits a signal B corresponding to the signal A. When the in-vehicle device receives the signal B from the portable device, it determines that the portable device is in the car. Then, the vehicle-mounted device transmits a signal for permitting engine start to the control unit described above. When the control unit receives the signal from the in-vehicle device, the control unit validates the operation of the changeover switch for starting and stopping the engine of the automobile, for example. The driver can start the engine of the automobile by turning on the changeover switch, for example. Or it becomes possible to stop the engine of a motor vehicle by turning off the changeover switch concerned, for example.

As described above, in a vehicle equipped with a smart ignition function, the engine of the vehicle can be started / stopped by the above-described changeover switch if the portable device is in the vehicle.
JP 2001-351453 A

  However, in a car equipped with the smart ignition function as described above, the driver does not need to insert the key into the keyhole to start the car engine. I forgot it. Furthermore, since it is possible to start and stop the engine wherever the portable device is placed in the automobile, the portable device moves due to, for example, vibration during traveling of the automobile, and the portable device is lost. There was a fear.

  Therefore, an object of the present invention is to provide a position detection system capable of detecting the position of a second communication device (for example, a portable device), a position detection method for the position detection system, a position detection communication device, and a communication device. To do.

  The invention for solving the problem is a position detection system for detecting the position of the second communication device based on a plurality of distances between the plurality of first communication devices and the second communication device, Each of the plurality of first communication devices transmits a distance calculation signal for calculating a distance between the second communication device and the distance calculation signal from the second communication device. A detection unit that detects a phase difference between the distance calculation signal at the time of transmission and a signal according to the distance calculation signal at the time of reception. And a calculation unit that calculates a distance to the second communication device based on the detected phase difference, wherein the second communication device is transmitted from the plurality of first communication devices. A second transmitter for transmitting a signal corresponding to the distance calculation signal Comprising, based on the plurality of distances calculated by plurality of the calculation unit of the plurality of first communication device comprises a position detector for detecting a position of the second communication device, characterized in that.

  Moreover, it is a position detection system which detects the position of the said 2nd communication apparatus based on the some distance between a 1st communication apparatus and a 2nd communication apparatus, Comprising: The said 1st communication apparatus is a said 2nd communication. A first transmitter for transmitting a distance calculation signal for calculating a distance to the device, a plurality of receivers for receiving a signal corresponding to the distance calculation signal from the second communication device, The plurality of receiving units receive a signal corresponding to the distance calculation signal from the second communication device, so that the distance calculation signal when transmitted and the distance calculation signal when received are determined. And a calculation unit that calculates the plurality of distances to the second communication device based on the plurality of phase differences detected by the detection unit. The second communication device includes the first communication device. A position for detecting the position of the second communication device based on the plurality of distances calculated by the calculation unit, the second transmission unit transmitting a signal according to the distance calculation signal transmitted from It has a detection part.

  Further, the position detection method of the position detection system detects the position of the second communication device based on a plurality of distances between the plurality of first communication devices and the second communication device. Each communication device transmits a distance calculation signal for calculating a distance to the second communication device, and the second communication device transmits the distance calculation signal transmitted from the plurality of first communication devices. A signal corresponding to the signal, and each of the plurality of first communication devices receives the signal corresponding to the distance calculation signal from the second communication device and transmits the distance calculation signal when the signal is transmitted. The phase difference with the signal corresponding to the distance calculation signal when received is detected, the distance to the second communication device is calculated based on the phase difference, and the plurality of first communication devices Based on the calculated plurality of distances, the second Detecting the position of the communication apparatus, characterized in that.

  Further, the position detection communication device transmits a distance calculation signal for calculating a distance to the counterpart communication device, and a signal corresponding to the distance calculation signal from the counterpart communication device. By receiving, the detection unit for detecting a phase difference between the distance calculation signal when transmitted and the signal according to the distance calculation signal when received, and the detection unit detects the phase difference A plurality of communication devices having a calculation unit that calculates a distance to the counterpart communication device based on a phase difference, and based on the plurality of distances calculated by the plurality of calculation units, The position of the counterpart communication device is detected.

  Further, the communication device transmits the distance calculation signal for calculating the distance, and receives the signal for distance calculation when transmitted by receiving the signal according to the returned distance calculation signal. A plurality of distance calculation communication devices that detect a phase difference with a signal corresponding to the distance calculation signal and calculate a distance from a transmission position of the signal according to the distance calculation signal based on the phase difference The distance calculation transmitted from the counterpart communication device is capable of communicating with the counterpart communication device that detects the transmission position based on the plurality of distances calculated by the plurality of distance calculation communication devices. And a transmission unit that transmits a signal corresponding to the signal for use.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the position detection system which can detect the position of a 2nd communication apparatus, the position detection method of a position detection system, a position detection communication apparatus, and a communication apparatus.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

<< Embodiment >>
=== Overall Configuration of Position Detection System, Position Detection Communication Device, and Communication Device ===
A position detection system, a position detection communication apparatus, and a communication apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a functional block diagram showing an example of the overall configuration of a position detection system, a position detection communication apparatus, and a position detection apparatus according to the present invention. In the present embodiment, the position detection system will be described as being used, for example, in an automobile equipped with a smart ignition function. The position detection system includes vehicle-mounted devices 1A, 1B, 1C, 1D (first communication device), a portable device 2 (second communication device), and a CPU (Central Processing Unit) 90 (position detection unit). In addition, the position detection communication device is configured from in-vehicle devices 1A, 1B, 1C, and 1D (communication device), and the counterpart communication device is used for the portable device 2. Further, the communication device is used for the portable device 2, and the counterpart communication device is composed of the in-vehicle devices 1 </ b> A, 1 </ b> B, 1 </ b> C, 1 </ b> D (distance calculation communication device). FIG. 3 is a diagram illustrating detection of the portable device 2 by the in-vehicle devices 1A, 1B, 1C, and 1D. If the + X direction in FIG. 3 is the front direction of the automobile, for example, the in-vehicle device 1A is provided on the front left side, the in-vehicle device 1B is provided on the front right side, and the in-vehicle device 1C is provided on the rear left side. Is provided on the rear right side. Moreover, CPU90 shall be provided in the motor vehicle provided with vehicle equipment 1A, 1B, 1C, 1D. It is assumed that the portable device 2 is provided on a car key. In the present embodiment, four in-vehicle devices are provided, but the present invention is not limited to this. For example, more in-vehicle devices may be provided so as to reliably detect the position of the portable device 2.

  In the present embodiment, a low-frequency (for example, 125 kHz) carrier wave is used in signal communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2. Further, in the signal communication from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D, a high frequency (for example, 312 MHz) carrier wave is used. That is, in the communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2, the communication speed is slow because communication is performed using a low-frequency carrier wave. On the contrary, in communication from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D, the communication speed is increased because communication is performed using a high-frequency carrier wave. The reason for using a low frequency with a low communication speed is that the time when signals are transmitted from the in-vehicle devices 1A, 1B, 1C and 1D and the time when the signals are returned via the portable device 2 as described later. This is to intentionally generate a signal phase difference (may be a time difference). In the case of communication from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D, by using a high frequency with a high communication speed, the phase difference therebetween is changed from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2. Compared to the phase difference that occurs during communication, the level is negligible. That is, the distance between the in-vehicle devices 1A, 1B, 1C, and 1D and the portable device 2 is calculated using only the phase difference intentionally generated in the communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2. It becomes possible. Therefore, the intentional low frequency is used for communication from the in-vehicle devices 1A, 1B, 1C, 1D to the portable device 2, and the higher frequency is used for communication from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, 1D. Yes.

  Further, in the communication from the vehicle-mounted devices 1A, 1B, 1C, and 1D to the portable device 2 as described above, communication is performed using a signal that has been subjected to ASK modulation (Amplitude Shift Keying). This is because the transmitters 7A, 7B, 7C, and 7D (first transmitter and first modulator) for transmitting signals from the vehicle-mounted devices 1A, 1B, 1C, and 1D to the portable device 2 and the vehicle-mounted device 1A, The circuit configuration of the demodulator 24 (second demodulator) for receiving signals from 1B, 1C, and 1D is easy, and even if there is some interference, data is transmitted from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2. Because it becomes possible. In communication from the portable device 2 to the vehicle-mounted devices 1A, 1B, 1C, and 1D, communication is performed using a signal that has been subjected to FSK modulation (frequency shift keying). This is because a signal subjected to FSK modulation is not easily affected by noise, and can be reliably transmitted without loss of information from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D. It is. In the present embodiment, communication is performed using an ASK-modulated signal in communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2, and the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D. However, the communication is not limited to this. For example, it is possible to improve the confidentiality of signals, and communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2 and the in-vehicle from the portable device 2 with a spread spectrum that has a remarkably high ability to eliminate interference waves and interference waves. It is also possible to communicate with the machines 1A, 1B, 1C, 1D.

  The CPU 90 performs overall control of the in-vehicle devices 1A, 1B, 1C, and 1D.

  The in-vehicle device 1A includes a CPU 3A (detection unit, calculation unit), a counter 4A, a timer 5A, a Flash memory 6A (storage unit), a transmission unit 7A, a reception unit 8A (first demodulation unit), a transmission antenna 9A, a reception antenna 10A, An OSC 26A (oscillator circuit: Oscillator) is included.

  The transmitter 7A ASK modulates the signal from the CPU 3A with a carrier wave having a frequency of 125 kHz.

  The transmission antenna 9A transmits a signal that has been ASK modulated by the transmission unit 7A.

  The receiving antenna 10 </ b> A receives the FSK modulated signal from the portable device 2.

  The receiving unit 8A demodulates the FSK-modulated signal from the portable device 2 received by the receiving antenna 10A.

  The CPU 3A is provided for overall control of the in-vehicle device 1A. In the flash memory 6A, program data for the CPU 3A to perform processing described later is stored in advance. The flash memory 6A is composed of a nonvolatile memory element that can repeatedly write and read data by electrically erasing the data.

  The timer 5A measures time based on an instruction from the CPU 3A.

  The OSC 26A transmits a clock (CLK0) having a predetermined frequency to the CPU 3A.

  The counter 4A is based on an instruction from the CPU 90, from the rise of a signal (hereinafter referred to as a distance calculation signal) for calculating the distance from the in-vehicle device 1A to the portable device 2 transmitted from the CPU 3A to the transmission unit 7A. For example, the rising edge of the clock from the OSC 26A is counted. Then, the counter 4A counts the rising edge of the clock from the OSC 26A until the rising edge of the distance calculation signal demodulated by the receiving unit 8A. The count value of the counter 4A is reset based on an instruction from the CPU 3A.

  Based on the instruction signal from the CPU 90, the CPU 3A transmits a signal (hereinafter referred to as an in-vehicle confirmation signal A) for confirming whether or not the portable device 2 is in the automobile to the transmission unit 7A. The CPU 3A transmits the in-vehicle confirmation signal B from the portable device 2 demodulated by the receiving unit 8A. The CPU 3A transmits a signal (hereinafter referred to as a confirmation signal) based on the transmission of the in-vehicle confirmation signal B to the CPU 90. The CPU 3A transmits a signal (hereinafter referred to as an unconfirmed signal) based on the fact that the in-vehicle confirmation signal B has not been transmitted to the CPU 90. Further, the CPU 3A transmits a signal (hereinafter referred to as an inverter operation instruction signal) for setting the inverter 21 (reply unit) to an operation state based on the instruction signal from the CPU 90 to the transmission unit 7A. The CPU 3A transmits a signal (hereinafter referred to as an inverter non-operation instruction signal) for making the inverter 21 non-operational to the transmission unit 7A. Further, the CPU 3A transmits the above-described distance calculation signal to the transmission unit 7A and resets the counter 4A to start counting. In addition, the CPU 3A resets the timer 5A to start measuring time. When the CPU 3A receives the distance calculation signal from the portable device 2 demodulated by the receiving unit 8A, the CPU 3A reads the count value of the counter 4A. The CPU 3A calculates the distance from the in-vehicle device 1A to the portable device 2 based on the count value. That is, the count value indicating the phase difference between the two signals from the time when the distance calculation signal is transmitted to the transmitter 7A to the time when the distance calculation signal is returned via the portable device 2 is obtained. The distance from the machine 1A to the portable machine 2 can be calculated. For example, when the frequency of the clock from the OSC 26A is 15.75 kHz, the count value of the counter 4A when the distance calculation signal is returned via the portable device 2 is 250. The phase difference is about 15.87 (msec). It is assumed that the distance from the vehicle-mounted device 1A to the portable device 2 when the phase difference is about 15.87 (msec) is about 1 (m), for example, from an experiment. The distance data corresponding to the count value obtained from this experiment is stored in advance in the Flash memory 6A as table data, for example. The CPU 3A transmits the calculated distance information from the in-vehicle device 1A to the portable device 2 to the CPU 90.

  The configuration of the in-vehicle devices 1B, 1C, and 1D is the same as that of the in-vehicle device 1A described above. The vehicle-mounted devices 1A, 1B, 1C, and 1D may simultaneously perform the above-described processing based on an instruction from the CPU 90, or may sequentially perform the above-described processing.

  Based on an instruction signal from a control unit (not shown) provided in the automobile, the CPU 90 transmits an instruction signal for the CPU 3A, 3B, 3C, 3D to transmit the above-described in-vehicle confirmation signal A. Send to 1C, 1D. The CPU 90 transmits a signal for permitting the engine start of the vehicle (hereinafter referred to as an engine start permission signal) to the control unit based on the above-described confirmation signals from the in-vehicle devices 1A, 1B, 1C, and 1D. Further, the CPU 90 transmits a signal for not permitting the engine start of the vehicle (hereinafter referred to as an engine start non-permission signal) to the control unit based on the above-described unconfirmed signals from the in-vehicle devices 1A, 1B, 1C, and 1D. . The CPU 90 transmits a signal (hereinafter referred to as a detection signal) for detecting the portable device 2 from the control unit. Based on the detection signal, the CPU 90 transmits an instruction signal for the CPU 3A, 3B, 3C, 3D to transmit the inverter operation instruction signal described above to the in-vehicle devices 1A, 1B, 1C, 1D. And CPU90 transmits the instruction | indication signal for making CPU3A, 3B, 3C, 3D calculate the distance from vehicle equipment 1A, 1B, 1C, 1D to the portable device 2 to vehicle equipment 1A, 1B, 1C, 1D. The CPU 90 transmits distance information from the in-vehicle devices 1A, 1B, 1C, 1D to the portable device 2 calculated by the CPUs 3A, 3B, 3C, 3D. The CPU 90 detects the position of the portable device 2 based on the distance information calculated by the CPUs 3A, 3B, 3C, and 3D. In detecting the position of the portable device 2, the CPU 90 reads out program data for detecting the position of the portable device 2 stored in a memory (not shown). And in the calculation processing of the program by the CPU 90, the position of the portable device 2 can be detected by using the coincidence point of each distance read from the distance information from the in-vehicle devices 1A, 1B, 1C, 1D. For example, the distance to the portable device 2 calculated by the vehicle-mounted device 1A is 120 cm, the distance to the portable device 2 calculated by the vehicle-mounted device 1B is 212 cm, the distance to the portable device 2 calculated by the vehicle-mounted device 1C is 20 cm, and the vehicle-mounted device 1D. Assume that the distance from the mobile device 2 to the portable device 2 is 117 cm. At that time, the CPU 90 has a point where the distance from the vehicle-mounted device 1A is 120 cm, a point where the distance from the vehicle-mounted device 1B is 212 cm, a point where the distance from the vehicle-mounted device 1C is 20 cm, and a point from the vehicle-mounted device 1D. A point at which the distance of 117 cm coincides is calculated, and it is determined that the portable device 2 is on the coincidence point.

  The portable device 2 includes a CPU 11 (switching unit), a Flash memory 13, a demodulation unit 24, a modulation unit 25 (second transmission unit and second modulation unit), a reception antenna 18, a transmission antenna 19, and inverters 20, 21, and 22. is doing.

  The receiving antenna 18 receives ASK-modulated signals from the in-vehicle devices 1A, 1B, 1C, and 1D.

  The demodulator 24 is composed of, for example, RF 16 (Radio Frequency) and DET 14 (Detector). The demodulator 24 demodulates the ASK-modulated signal from the receiving antenna 18.

  The modulation unit 25 includes, for example, an RF 17 and a modulator 15. The modulation unit 25 performs FSK modulation on the signal from the CPU 11 with a carrier wave having a frequency of 312 MHz. Further, the modulation unit 25 performs FSK modulation of the signal from the demodulation unit 24 with a carrier wave having a frequency of 312 MHz when the inverter 21 is in an operation state according to an instruction from the CPU 11.

  The transmission antenna 19 transmits the signal that has been FSK modulated by the modulation unit 25.

  The CPU 11 is provided for overall control of the portable device 2. The flash memory 13 stores in advance program data for the CPU 11 to perform processing to be described later. The flash memory 13 is composed of a nonvolatile memory element that can repeatedly write and read data by electrically erasing the data.

  The CPU 11 transmits an in-vehicle confirmation signal A from the in-vehicle devices 1A, 1B, 1C, 1D demodulated by the demodulator 24. Based on the vehicle interior confirmation signal A, the CPU 11 transmits the vehicle interior confirmation signal B to the modulation unit 25. The CPU 11 transmits inverter operation instruction signals from the vehicle-mounted devices 1A, 1B, 1C, and 1D demodulated by the demodulator 24. The CPU 11 puts the inverter 21 into an operating state based on the inverter operation instruction signal. Therefore, no processing is performed on the signals from the vehicle-mounted devices 1A, 1B, 1C, and 1D demodulated by the demodulator 24, and the signals are directly FSK modulated by the modulator 25 and transmitted from the transmission antenna 19. It becomes possible. The CPU 11 transmits the inverter non-operation instruction signal from the in-vehicle devices 1A, 1B, 1C, and 1D demodulated by the demodulator 24, and makes the inverter 21 non-operation based on the inverter non-operation instruction signal. Note that these functions of the CPU 11 are realized by the CPU 11 executing the program based on the result of decoding the program data read from the flash memory 13 described above. The CPU 11 includes an address counter (not shown) that specifies an address of the flash memory 13, a program logic array (not shown) that decodes program data read from the flash memory 13, an arithmetic logic unit (not shown) that performs a logical operation, an arithmetic operation It has a register (not shown) for temporarily storing data.

=== Operation of Position Detection System ===
The operation of the position detection system, position detection communication apparatus, and communication apparatus according to the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing an example of operations of the position detection system, the position detection communication device and the counterpart communication device, and the communication device and the counterpart communication device according to the present invention. FIG. 4 is a diagram illustrating an example of a display screen of the monitor 92 (display unit).

  In the present embodiment, the owner of the portable device 2 (hereinafter referred to as the “carrier”) unlocks the door of the automobile, gets into the automobile, places the portable device 2 somewhere in the automobile, and the carrier A case where the position of the portable device 2 has been forgotten will be described. Further, it is assumed that the inverter 21 is in an inoperative state.

  A control unit (not shown) separately provided in the automobile receives a signal based on the closure of the automobile door (S301). The control unit transmits a signal for confirming whether to start the engine based on the signal to the CPU 90.

  And CPU90 transmits the instruction | indication signal for CPU3A, 3B, 3C, 3D to transmit the vehicle interior confirmation signal A to vehicle equipment 1A, 1B, 1C, 1D based on the said signal from a control part.

  Hereinafter, although the operation of the in-vehicle device 1A will be described, the same operation is performed for the in-vehicle devices 1B, 1C, and 1D.

  CPU3A will transmit the vehicle interior confirmation signal A to the transmission part 7A, if the instruction | indication signal mentioned above from CPU90 is received (S302). At this time, the CPU 3A resets the timer 5A. The reset timer 5A starts measuring time. Then, the CPU 3A determines whether or not the in-vehicle confirmation signal B from the portable device 2 demodulated by the receiving unit 8A is transmitted within a predetermined time (S303). The transmitter 7A ASK modulates the in-vehicle confirmation signal A with a carrier wave having a frequency of 125 kHz. Then, the ASK-modulated in-vehicle confirmation signal A from the transmission unit 7A is transmitted via the transmission antenna 9A.

  When the reception antenna 18 of the portable device 2 receives the ASK-modulated in-vehicle confirmation signal A, the demodulator 24 demodulates the ASK-modulated in-vehicle confirmation signal A. If the CPU 11 determines that the vehicle interior confirmation signal A demodulated by the demodulator 24 is transmitted (S401: YES), the CPU 11 transmits the vehicle interior confirmation signal B to the modulator 25 (S402). The modulation unit 25 performs FSK modulation on the vehicle interior confirmation signal B from the CPU 11 with a carrier wave having a frequency of 312 MHz. The vehicle interior confirmation signal B that has been FSK modulated by the modulator 25 is transmitted via the transmission antenna 19.

  When the reception antenna 10A of the vehicle-mounted device 1A receives the FSK-modulated in-vehicle confirmation signal B, the receiving unit 8A demodulates the FSK-modulated in-vehicle confirmation signal B. When determining that the in-vehicle confirmation signal B from the portable device 2 demodulated by the receiving unit 8A has been transmitted (S303: YES), the CPU 3A transmits a confirmation signal to the CPU 90 (S320). Similarly, CPU3B, 3C, 3D of vehicle equipment 1B, 1C, 1D will transmit a confirmation signal to CPU90, if it determines that the vehicle interior confirmation signal B from the portable device 2 was transmitted. The CPUs 3A, 3B, 3C, and 3D do not transmit the vehicle interior confirmation signal B demodulated by the receiving units 8A, 8B, 8C, and 8D within a predetermined time after the vehicle interior confirmation signal A is transmitted. (S303, NO), an unconfirmed signal is transmitted to the CPU 90 (S321).

  CPU90 transmits an engine start permission signal to a control part (not shown) based on the confirmation signal from vehicle equipment 1A, 1B, 1C, 1D (S304). In response to the engine start permission signal from the CPU 90, for example, the control unit starts driving the engine of the automobile. The CPU 90 transmits an engine start non-permission signal to the control unit based on the unconfirmed signals from the in-vehicle devices 1A, 1B, 1C, and 1D (S318). Then, the control unit does not start driving the automobile engine until the key is inserted into the keyhole (S319).

  For example, when the portable person places the portable device 2 somewhere in the automobile and forgets the position of the portable apparatus 2, the portable person detects the portable apparatus 2 in an input unit (not shown) provided in the automobile. Input instructions to do. The control unit receives an instruction signal based on an instruction input to the input unit. Then, the control unit transmits a detection signal to the CPU 90 based on the instruction signal. When the CPU 90 receives the detection signal from the control unit (YES in S305), the CPU 3A, 3B, 3C, 3D transmits an instruction signal for transmitting the inverter operation instruction signal to the vehicle-mounted devices 1A, 1B, 1C, 1D. .

  CPU3A will transmit an inverter operation instruction signal to the transmission part 7A, if the instruction | indication signal mentioned above from CPU90 is received (S306). The transmitter 7A ASK-modulates the inverter operation instruction signal with a carrier wave having a frequency of 125 kHz. Then, the ASK-modulated inverter operation instruction signal from the transmission unit 7A is transmitted via the transmission antenna 9A.

  When the receiving antenna 18 of the portable device 2 receives the ASK-modulated inverter operation instruction signal, the demodulator 24 demodulates the ASK-modulated inverter operation instruction signal. When the CPU 11 determines that the inverter operation instruction signal demodulated by the demodulator 24 has been transmitted (YES in S403), the CPU 11 sets the inverter 21 in an operating state (S404).

  When the CPU 3A transmits the inverter operation instruction signal described above, the CPU 3A transmits a distance calculation signal to the transmitter 7A (S307). At this time, the CPU 3A resets the counter 4A, and causes the counter 4A to start counting from the rise of the distance calculation signal. Further, the CPU 3A resets the timer 5A to start timing. Then, the CPU 3A determines whether or not the distance calculation signal is returned from the portable device 2 within a predetermined time (S308). The transmitter 7A ASK modulates the distance calculation signal with a carrier wave having a frequency of 125 kHz. Then, the ASK-modulated distance calculation signal from the transmitter 7A is transmitted via the transmission antenna 9A.

  When the reception antenna 18 of the portable device 2 receives the ASK-modulated distance calculation signal, the demodulation unit 24 demodulates the ASK-modulated distance calculation signal. At this time, the distance calculation signal from the in-vehicle device 1A demodulated by the demodulator 24 is transmitted to the modulator 25 as it is because the inverter 21 is in an operating state (S406). The modulation unit 25 performs FSK modulation on the distance calculation signal from the demodulation unit 24 with a carrier wave having a frequency of 312 MHz. The distance calculation signal that has been FSK modulated by the modulator 25 is transmitted via the transmission antenna 19.

  When the receiving antenna 10A of the vehicle-mounted device 1A receives the FSK-modulated distance calculation signal, the receiving unit 8A demodulates the FSK-modulated distance calculation signal. When determining that the distance calculation signal from the portable device 2 demodulated by the receiving unit 8A has been transmitted (YES in S308), the CPU 3A reads the count value of the counter 4A. Then, the CPU 3A calculates the distance from the in-vehicle device 1A to the portable device 2 based on the count value. As described above, in communication from the in-vehicle device 1A to the portable device 2, a low-frequency 125 kHz carrier wave is used. In communication from the portable device 2 to the in-vehicle device 1A, a carrier wave of 312 MHz that is a high frequency is used. Therefore, the phase difference in the communication from the portable device 2 to the in-vehicle device 1A is negligible compared to the phase difference generated in the communication from the in-vehicle device 1A to the portable device 2. Therefore, an intentional phase difference is generated between the distance calculation signal transmitted from the CPU 3A to the transmission unit 7A and the distance calculation signal demodulated by the reception unit 8A by using a low frequency of 125 kHz. Therefore, the count value read by the CPU 3A described above indicates the phase difference. Then, the CPU 3A reads the distance corresponding to the count value obtained from the experiment stored as table data in the Flash memory 6A. Therefore, the CPU 3 can calculate the distance from the in-vehicle device 1A to the portable device 2 using the count value indicating the phase difference. In the present embodiment, the distance from the in-vehicle device 1A to the portable device 2 is calculated based on the count value of the counter 4A. For example, the CPU 3A counts the timer 5A when the CPU 3A transmits the distance calculation signal to the transmission unit 7A, and the distance calculation signal from the portable device 2 modulated by the reception unit 8A is transmitted. Read the time counted by the timer 5A. It is also possible to calculate the distance from the in-vehicle device 1A to the portable device 2 using the time measured by the timer 5A. Further, the calculation of the distance from the in-vehicle device 1A to the portable device 2 by the CPU 3A is not limited to once. For example, the distance from the in-vehicle device 1A to the portable device 2 can be calculated a plurality of times, and the distance from the in-vehicle device 1A to the portable device 2 can be calculated more reliably. At this time, the CPU 3A may be configured to repeatedly transmit the distance calculation signal until the distance calculation signal is returned from the portable device 2. Then, the CPU 3A transmits the calculated distance information from the in-vehicle device 1A to the portable device 2 to the CPU 90 (S310). Similarly, the CPU 3B of the in-vehicle device 1B transmits distance information from the in-vehicle device 1B to the portable device 2 to the CPU 90 (S311). Further, the CPU 3C of the in-vehicle device 1C transmits distance information from the in-vehicle device 1C to the portable device 2 to the CPU 90 (S312). Further, the CPU 3D of the in-vehicle device 1D transmits distance information from the in-vehicle device 1D to the portable device 2 to the CPU 90 (S313). Further, the CPU 3A calculates the distance from the in-vehicle device 1A to the portable device 2 and transmits an inverter non-operation instruction signal to the transmission unit 7A (S309). The transmitter 7A ASK-modulates the inverter non-operation instruction signal with a carrier wave having a frequency of 125 kHz. Then, the ASK-modulated inverter non-operation instruction signal from the transmission unit 7A is transmitted via the transmission antenna 9A. If the CPU 3A determines that the distance calculation signal demodulated by the receiving unit 8A is not returned within a predetermined time after transmitting the distance calculation signal (NO in S308), the CPU 3A performs distance calculation. Information determined that no signal is returned is stored in order, for example, from address 1 of the Flash memory 6A. At this time, the CPU 3A determines whether or not the information determined that the distance calculation signal is not returned is stored in the address 2 (S316). If the CPU 3A determines that the information is not stored at the address 2 (NO in S316), the CPU 3A transmits the inverter operation instruction signal to the transmitter 7A again (S306). Further, as described above, the CPU 3A resets the timer 5A to start timing, and resets the counter 4A to start counting. If the CPU 3A determines that the distance calculation signal is not returned again (NO in S308), the CPU 3A stores the information determined that the distance calculation signal is not returned, for example, at address 2 of the Flash memory 6A (S316). ). If the CPU 3A determines that the information determined that the distance calculation signal has not been returned is stored in the address 2 (YES in S316), the CPU 3A transmits a signal based on the determination to the CPU 90. CPU90 will discriminate | determine that the portable device 2 is not in a motor vehicle, if the said signal from not only the vehicle equipment 1A but the vehicle equipment 1B, 1C, 1D is received (S317). Then, the CPU 90 transmits an instruction signal to a control unit (not shown) to display on the monitor 92 that the portable device 2 is not in the automobile. Based on the instruction signal from the CPU 90, the control unit causes the monitor 92 to display that the portable device 2 is not in the vehicle (S315).

  As described above, when receiving the above-described distance information from the in-vehicle devices 1A, 1B, 1C, and 1D, the CPU 90 detects where the portable device 2 is in the vehicle based on the distance information (S314). At this time, the position of the portable device 2 by the CPU 90 is detected by using the in-vehicle device 1A as a starting point, the distance point calculated by the CPU 3A from the starting point (FIG. 3, one-dot chain line A), and the in-vehicle device 1B. The distance point calculated by the CPU 3B from the start point as a start point (FIG. 3, two-dot chain line B), the distance point calculated by the CPU 3C from the start point as the on-vehicle device 1C (FIG. 3, broken line C), and the on-vehicle device The distance is calculated from the point where 1D is the starting point and the distance point (solid line D in FIG. 3) calculated by the CPU 3D from the starting point coincides. Then, the CPU 90 transmits an instruction signal to the control unit so as to display the detected position of the portable device 2 on the monitor 92. The control unit displays the position of the portable device 2 on the monitor 92 based on the instruction signal from the CPU 90 (S315, FIG. 4).

  As described above, when the portable person forgets the position of the portable device 2, the CPU 3A, 3B, 3C, and 3D calculate the distances from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2 by the distance calculation signals. By doing so, the CPU 90 can detect the position of the portable device 2.

  According to this embodiment, from the phase difference between the distance calculation signal transmitted from the in-vehicle device 1A and the signal according to the distance calculation signal from the portable device 2, the CPU 3A performs the in-vehicle device 1A and the portable device 2. It is possible to calculate the distance between the two. In addition, by providing a plurality of in-vehicle devices, the CPU 90 allows the position of the portable device based on a plurality of distances between the in-vehicle devices 1A, 1B, 1C, 1D and the portable device 2 calculated by the CPUs 3A, 3B, 3C, 3D. Can be detected.

  Further, the inverter 21 can return the distance calculation signals from the in-vehicle devices 1A, 1B, 1C, and 1D as they are. Therefore, the CPUs 3A, 3B, 3C, and 3D transmit the distance calculation signals transmitted from the transmission units 7A, 7B, 7C, and 7D and the distances transmitted from the transmission units 7A, 7B, 7C, and 7D returned from the portable device 2. Since the distance to the portable device 2 is calculated from the same distance calculation signal as the calculation signal, it is possible to reliably calculate an accurate distance.

  Further, in communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2, a phase difference can be intentionally generated by performing communication using a low-frequency carrier wave. Further, in communication from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D, the communication is performed using a high-frequency carrier wave, so that the level generated by the communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2 The phase difference can be neglected compared to the phase difference. That is, the distance from the in-vehicle devices 1A, 1B, 1C, 1D to the portable device 2 can be calculated based on the phase difference intentionally generated in the communication from the in-vehicle devices 1A, 1B, 1C, 1D to the portable device 2. It becomes possible.

  Further, by setting the inverter 21 in the operating state in the CPU 11, the distance calculation signal can be returned to the in-vehicle devices 1 A, 1 B, 1 C, and 1 D, and the CPU 3 A, 3 B, 3 C, and 3 D are connected to the portable device 2. It is possible to calculate the distance. Further, by setting the inverter 21 in the non-operating state by the CPU 11, signals transmitted from the in-vehicle devices 1 </ b> A, 1 </ b> B, 1 </ b> C, 1 </ b> D are not returned from the portable device 2 as they are. Therefore, for example, in response to request signals from the vehicle-mounted devices 1A, 1B, 1C, and 1D, the portable device 2 can transmit a response signal that has been subjected to predetermined processing.

  In addition, in the communication from the vehicle-mounted devices 1A, 1B, 1C, and 1D that perform communication using a low-frequency carrier wave to the portable device 2, the transmitters 7A and 7B are used by using ASK modulation suitable for modulation using the low-frequency carrier wave. 7C, 7D and the demodulator 24 can be easily configured, and even if there is some interference, transmission from the in-vehicle devices 1A, 1B, 1C, 1D to the portable device 2 becomes possible. In communication from the portable device 2 that communicates with a high frequency carrier wave to the in-vehicle devices 1A, 1B, 1C, and 1D, it becomes less susceptible to noise by using FSK modulation suitable for modulation with a high frequency carrier wave. The information from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D can be reliably transmitted without loss.

  Further, the spread spectrum communication is performed by performing spread spectrum communication in the communication from the in-vehicle devices 1A, 1B, 1C, and 1D to the portable device 2 and the communication from the portable device 2 to the in-vehicle devices 1A, 1B, 1C, and 1D. It is possible to improve the confidentiality of the signal transmitted by the mobile phone and to remarkably increase the ability to eliminate interference waves and interference waves.

  In addition, timers 5A, 5B, 5C, and 5D for detecting a phase difference, counters 4A, 4B, 4C, and 4D that count with a clock having a predetermined frequency, and CPUs 3A, 3B, 3C, and 3D are carried based on the count value. The CPUs 3A, 3B, 3C, and 3D calculate the distance to the portable device 2 using the Flash memories 6A, 6B, 6C, and 6D in which table data that is a basis for calculating the distance to the device 2 is stored. It is possible to reliably do this. In addition, the timers 5A, 5B, 5C, and 5D and the counters 4A, 4B, 4C, and 4D are reset each time the CPUs 3A, 3B, 3C, and 3D transmit a distance calculation signal, so that the CPUs 3A, 3B, 3C, The distance between the portable device 2 is calculated from the distance calculation signal when the 3D is transmitted and the same distance calculation signal as the distance calculation signal transmitted by the CPUs 3A, 3B, 3C, and 3D when the 3D is received. It is possible for the unit to calculate with certainty.

  In addition, the position of the portable device 2 detected by the CPU 11 based on the plurality of distances calculated by the CPUs 3A, 3B, 3C, and 3D can be displayed on the monitor 92 provided in the automobile. Therefore, the position of the portable device 2 can be surely notified.

=== Other Embodiments ===
As described above, the position detection system, the position detection communication apparatus, and the communication apparatus according to the present invention have been described with respect to the detection of the position of the portable device 2, but the above description is for facilitating the understanding of the present invention. It is not intended to limit the invention. The present invention can be changed and improved without departing from the gist thereof.

<< Position Detection System, Position Detection Communication Device, Other Forms of Communication Device >>
In the present embodiment, the in-vehicle devices 1A, 1B, 1C, and 1D are provided at the above-described positions of the automobile, but the present invention is not limited to this.

  For example, only the receiving unit 8A and the receiving antenna 10A, the receiving unit 8B and the receiving antenna 10B, the receiving unit 8C and the receiving antenna 10C, and the receiving unit 8D and the receiving antenna 10D are provided at the positions where the in-vehicle devices 1A, 1B, 1C, and 1D are provided. May be provided. In that case, for example, only one in-vehicle device is provided, and the in-vehicle device is provided with the CPU 3, the transmission unit 7, the transmission antenna 9, the OSC 26, the Flash memory 6, the timer 5, and the counter 4. Then, as described above, the distance calculation signal from the CPU 3 is transmitted from the transmission antenna 9 via the transmission unit 7. The CPU 3 has received the distance calculation signals in the order in which the receiving units 8A, 8B, 8C, and 8D received the distance calculation signals returned from the portable device 2 via the reception antennas 10A, 10B, 10C, and 10D, for example. The distance from the receiving antenna to the portable device 2 is calculated. Then, the CPU 90 may be provided so as to detect the position of the portable device 2 based on distance information from the receiving antennas 10A, 10B, 10C, and 10D calculated by the CPU 3 to the portable device 2.

<< Application of position detection system, position detection communication apparatus, communication apparatus >>
In the present embodiment, the position detection system, the position detection communication device, and the communication device are used in an automobile equipped with a smart ignition function, but the application target of the present invention is not limited to this.

  For example, the portable device 2 may be provided as a valuable item. When the valuables provided with the portable device 2 are lost, a distance calculation signal is transmitted from the searchers A, B, C, and D having the same functions as the in-vehicle devices 1A, 1B, 1C, and 1D. Then, when the searcher approaches the portable device 2 provided for the valuable items, the portable device 2 returns a distance calculation signal from the searchers A, B, C, and D. When the distance calculation signals from the portable device 2 are transmitted to the searchers A, B, C, and D, the searchers A, B, C, and D can calculate the distance to the portable device 2. Based on the distance to the portable device 2 calculated by the searchers A, B, C, and D, for example, a control unit that controls the searchers A, B, C, and D detects the position of the valuables. It is also possible to display the position of valuables on a separate monitor.

  In addition, a person who needs to specify whereabouts (for example, a kindergarten or an elderly person, hereinafter referred to as a person to be monitored) has the portable device 2 and has the same function as the vehicle-mounted devices 1A, 1B, 1C, 1D, B, C, and D are managed by a person who monitors the monitored person (hereinafter referred to as a monitoring person). Then, the in-area confirmation signal A same as the in-vehicle confirmation signal A is transmitted from the monitoring devices A, B, C, and D. If the monitored person leaves the communicable range, the same in-area confirmation signal as the in-vehicle confirmation signal B received by the monitoring devices A, B, C, D immediately before the monitored person leaves the communicable range. Based on B, the monitor can easily know the position where the monitored person has left the communicable range. This is because the monitoring apparatus determines whether or not the intra-area confirmation signal B is transmitted within a predetermined time after the intra-area confirmation signal A is transmitted. Therefore, the in-area confirmation signal B is transmitted earliest to the monitoring device closest to the monitored person. Therefore, the position where the monitored person leaves the communicable range can be determined by the monitoring device closest to the monitored person. Therefore, the search for the monitored person by the monitoring person becomes more reliable. Therefore, it is possible to prevent an accident due to the monitored person leaving the communicable range.

It is a figure which shows an example of the whole structure of the position detection system which concerns on this invention, a position detection communication apparatus, and a communication apparatus. It is a flowchart which shows an example of operation | movement of the position detection system which concerns on this invention, a position detection communication apparatus, the other party communication apparatus, a communication apparatus, and the other party communication apparatus. It is a figure which shows the detection of the portable device 2 by vehicle equipment 1A, 1B, 1C, 1D. It is a figure which shows an example of the display screen of the monitor.

Explanation of symbols

1 In-vehicle device 2 Portable device 3, 11, 90 CPU
4 Counter 5 Timer 6 and 13 Flash memory 7 Transmitter 8 Receiver 9 and 19 Transmit antenna 10 and 18 Receive antenna 14 DET
15 Modulator 16, 17 RF
20, 21, 22 Inverter 24 Demodulator 25 Modulator 26 OSC
92 Monitor

Claims (12)

A position detection system that detects a position of the second communication device based on a plurality of distances between the plurality of first communication devices and the second communication device,
Each of the plurality of first communication devices is
A first transmitter that transmits a distance calculation signal for calculating a distance to the second communication device;
By receiving a signal according to the distance calculation signal from the second communication apparatus, the distance calculation signal when transmitted and a signal according to the distance calculation signal when received A detection unit for detecting a phase difference;
A calculation unit that calculates a distance to the second communication device based on the phase difference detected by the detection unit;
The second communication device is
A second transmission unit that transmits a signal according to the distance calculation signal transmitted from the plurality of first communication devices;
And a position detection unit that detects a position of the second communication device based on the plurality of distances calculated by the plurality of calculation units of the plurality of first communication devices.
A position detection system characterized by that. The second communication device is
A reply unit that returns the distance calculation signals transmitted from the plurality of first communication devices;
The detector is
By receiving the distance calculation signal returned by the reply unit, a phase difference between the distance calculation signal when transmitted and the distance calculation signal when received is detected,
The position detection system according to claim 1. Each of the plurality of first communication devices is
A first modulation unit that modulates the distance calculation signal with a carrier of a first frequency; and the distance calculation modulated by a carrier of a second frequency higher than the first frequency from the second communication device. A first demodulator that demodulates the signal,
The second communication device is
A second demodulation unit that demodulates the distance calculation signal modulated by the first modulation unit from the plurality of first communication devices; and the distance calculation signal demodulated by the second demodulation unit. A second modulation unit that modulates with a carrier wave of a second frequency,
The position detection system according to claim 1 or claim 2, wherein The second communication device is
A switching unit that puts the reply unit into an operating state to send back the distance calculation signal;
The plurality of first communication devices include:
Transmitting a switching signal for setting the return unit in an operating state so that the calculation unit calculates a distance to the second communication device;
The switching unit sets the reply unit to an operating state based on the switching signals from the plurality of first communication devices.
The position detection system according to claim 2 or claim 3, wherein The first modulation unit performs ASK modulation on the distance calculation signal with a carrier wave of the first frequency,
The second demodulator demodulates the distance calculation signal ASK-modulated by the first modulator from the plurality of first communication devices,
The second modulation unit FSK-modulates the distance calculation signal demodulated by the second demodulation unit with a carrier wave of the second frequency,
The first demodulator demodulates the distance calculation signal FSK-modulated by the second modulator from the second communication device.
The position detection system according to claim 3 or 4, characterized by the above. To perform communication between the plurality of first communication devices and the second communication device using spread spectrum,
The first modulation unit first-modulates the distance calculation signal with a carrier wave having the first frequency, and then second-orders (spreads) the distance calculation signal first-order modulated with the carrier wave having the first frequency. ) Modulate and
The second demodulator despreads and demodulates the distance calculation signal second-order (spread) modulated by the first modulator from the plurality of first communication devices,
The second modulation unit first modulates the distance calculation signal despread and demodulated by the second demodulation unit with the carrier wave of the second frequency, and then 1 with the carrier wave of the second frequency. Second-order (spreading) modulation of the distance-modulated signal for distance calculation,
The first demodulator despreads and demodulates the distance calculation signal that is second-order (spread) modulated by the second modulator from the second communication device.
The position detection system according to claim 3 or 4, characterized by the above. Each of the plurality of first communication devices is
It is reset every time the first transmitter transmits the distance calculation signal, and measures the time until the plurality of first communication devices receive the distance calculation signal returned from the second communication device. A timer,
A counter that is reset every time the timer is reset, and that counts the phase difference detected by the detection unit with a clock having a predetermined frequency;
A storage unit storing information on which the calculation unit calculates a distance to the second communication device based on a count value of the counter;
The detector is
Detecting the time counted by the timer as the phase difference between the distance calculation signal when transmitted and the distance calculation signal when received;
The calculation unit includes:
Based on the count value when the counter counts the phase difference with the clock having the predetermined frequency and the information stored in the storage unit, the distance to the second communication device is calculated.
The position detection system according to any one of claims 2 to 6, wherein The plurality of first communication devices are provided in an automobile,
The position detector is
A signal for causing the display unit to display the position of the second communication device detected based on the plurality of distances with respect to a display unit provided in the automobile to display the position of the second communication device. Supply,
The position detection system according to any one of claims 1 to 7, wherein the position detection system is characterized in that: A position detection system for detecting a position of the second communication device based on a plurality of distances between the first communication device and the second communication device,
The first communication device is
A first transmitter that transmits a distance calculation signal for calculating a distance to the second communication device;
A plurality of receiving units for receiving signals according to the distance calculation signals from the second communication device;
The plurality of receiving units receive a signal corresponding to the distance calculation signal from the second communication device, and according to the distance calculation signal when transmitted and the distance calculation signal when received A detection unit for detecting a plurality of phase differences between
A calculation unit that calculates the plurality of distances with the second communication device based on the plurality of phase differences detected by the detection unit;
The second communication device is
A second transmitter that transmits a signal corresponding to the distance calculation signal transmitted from the first communication device;
And a position detector that detects a position of the second communication device based on the plurality of distances calculated by the calculator.
A position detection system characterized by that. A position detection method of a position detection system for detecting a position of the second communication device based on a plurality of distances between the plurality of first communication devices and the second communication device,
Each of the plurality of first communication devices transmits a distance calculation signal for calculating a distance to the second communication device,
The second communication device transmits a signal corresponding to the distance calculation signal transmitted from the plurality of first communication devices,
The plurality of first communication devices respectively receive the distance calculation signal when transmitted by receiving a signal corresponding to the distance calculation signal from the second communication device and the distance calculation signal when received Detecting a phase difference with a signal corresponding to the signal, calculating a distance to the second communication device based on the phase difference,
Detecting a position of the second communication device based on a plurality of distances calculated by the plurality of first communication devices;
A position detection method for a position detection system. A transmission unit for transmitting a distance calculation signal for calculating the distance between the communication apparatus on the other side,
By receiving the signal according to the distance calculation signal from the counterpart communication device, the distance calculation signal when transmitted and the signal according to the distance calculation signal when received A detection unit for detecting a phase difference;
A plurality of communication devices having a calculation unit that calculates a distance to the counterpart communication device based on the phase difference detected by the detection unit;
Detecting the position of the counterpart communication device based on the plurality of the distances calculated by the plurality of calculation units;
A position detecting communication device characterized by the above. Send a distance calculation signal to calculate the distance,
Detecting a phase difference between the distance calculation signal when transmitted by receiving a signal according to the returned distance calculation signal and the signal according to the distance calculation signal when received;
A plurality of distance calculation communication devices that calculate a distance to a transmission position of a signal according to the distance calculation signal based on the phase difference;
It is possible to communicate with a counterpart communication device that detects the transmission position based on a plurality of distances calculated by the plurality of distance calculation communication devices,
A transmission unit that transmits a signal according to the distance calculation signal transmitted from the counterpart communication device;
A communication device.

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