JP2021131399A - Distance measuring device and distance measuring method - Google Patents

Abstract

To make it possible to accurately calculate a distance by employing a communication type distance measurement obtaining a distance between two devices by communication between each of the devices.SOLUTION: A distance measuring device of an embodiment includes a first device having a first transceiver which transmits a first known signal corresponding to a first carrier frequency and a second known signal corresponding to a second carrier frequency different from the first carrier frequency and receives a third known signal corresponding to the first carrier frequency and a fourth known signal corresponding to the second carrier frequency; a second device having a second transceiver which transmits the third known signal and the fourth known signal and receives the first and the second known signals; and a calculation unit which calculates the distance between the first device and the second device on the basis of the phases of the first to fourth known signals. The first transceiver and the second transceiver perform total six times of transceiving comprising two times of transceiving for each of the first and the third kwon signals and one time transceiving for each of the second and the fourth kwon signals.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a distance measuring device and a distance measuring method.

In recent years, keyless entries that make it easier to lock and unlock cars have been adopted in many cars. This technology locks and unlocks doors using the key of the car and the communication between the cars. Further, in recent years, a smart entry system has been adopted in which a smart key can be used to lock / unlock the door lock and start the engine without touching the key.

However, there are many cases where an attacker breaks into the communication between the key and the car and steals the car. As a defensive measure against the above-mentioned attack (so-called relay attack), a measure is being studied in which the distance between the key and the vehicle is measured, and when the distance is determined to be greater than or equal to a predetermined distance, the control of the vehicle by communication is prohibited.

There are many distance measuring techniques such as a dual frequency CW (Continuous Wave) method, an FM (Frequency Modulated) CW method, a Doppler method, and a phase detection method. Generally, in distance measurement, a transmitter and a receiver are provided in the same housing of the measuring device, the radio wave emitted from the transmitter is applied to the object, and the reflected wave is detected by the receiver, from the measuring device to the object. The distance is calculated.

However, considering that the reflection coefficient of the object is relatively small, the output power is limited by the Radio Law, etc., the distance that can be measured by the distance measuring technology using the reflected wave is relatively small, and the above-mentioned relay attack is dealt with. Not enough to use as a countermeasure.

Japanese Unexamined Patent Publication No. 8-166443

An object of the embodiment is to provide a distance measuring device and a distance measuring method capable of accurately calculating a distance by adopting a communication type distance measuring in which the distance between two devices is obtained by communication between the devices. And.

The ranging device of the embodiment calculates the distance between the first device and the second device, which can move at least one of them, based on the phases of the first to fourth known signals transmitted at a plurality of carrier frequencies. In the distance measuring device, the first known signal corresponding to the first carrier frequency by using the output of the first reference signal source and the output of the first reference signal source and the second known signal different from the first carrier frequency. A second known signal corresponding to the carrier frequency is transmitted, and the third known signal corresponding to the first carrier frequency and the fourth known signal corresponding to the second carrier frequency are received. The first apparatus including one transmitter / receiver, the second reference signal source operating independently of the first reference signal source, and the output of the second reference signal source are used to obtain the first carrier frequency. A second transmitter / receiver that transmits the corresponding third known signal and the fourth known signal corresponding to the second carrier frequency and receives the first known signal and the second known signal. The second device provided, the first phase detector provided in the first device, the second phase detector provided in the second device, and the first device or the second device are provided. The first transmitter / receiver and the second transmitter / receiver are provided with a calculation unit for calculating the distance between the first apparatus and the second apparatus. Transmission and reception, transmission and reception of the third known signal in the second period, transmission and reception of the first known signal in the third period, transmission and reception of the second known signal in the fourth period, and transmission and reception in the fifth period. The fourth known signal is transmitted and received, the second known signal is transmitted and received in the sixth period, and the second phase detector determines the first phase of the first known signal in the first period. The first phase detector detects the second phase of the third known signal during the second period, and the second phase detector detects the first known signal during the third period. The second phase detector detects the fourth phase of the second known signal during the fourth period, and the first phase detector detects the fourth phase of the second known signal during the fifth period. The fifth phase of the fourth known signal was detected, the second phase detector detected the sixth phase of the second known signal in the sixth period, and the calculation unit detected the sixth phase. Using the first to sixth phases, the difference calculation between the first phase and the fourth phase and the difference calculation between the second phase and the fifth phase are included according to the phase detection interval. By the calculation, the first device and the second device The distance between the first and second transmitters and receivers was calculated, and one of the first and second transmitters and receivers was detected by the first or second phase detector based on the received signal with respect to the other of the first and second transmitters and receivers. A known signal generated by adding phase information as a phase offset is transmitted.

The block diagram which shows the distance measuring system which adopted the distance measuring device which concerns on 1st Embodiment of this invention. Explanatory drawing for explaining the principle of distance measurement by a phase detection method using a reflected wave and its problem. Explanatory drawing for explaining the principle of distance measurement by a phase detection method using a reflected wave and its problem. Explanatory drawing for demonstrating the problem of distance measurement by a phase detection method. Explanatory drawing for demonstrating the problem of distance measurement by a phase detection method. FIG. 6 is a circuit diagram showing an example of a specific configuration of the transmitting unit 14 and the receiving unit 15 in FIG. The circuit diagram which shows an example of the specific structure of the transmission part 24 and the receiving part 25 in FIG. The flowchart for demonstrating the operation of 1st Embodiment. Explanatory drawing for explaining the distance calculation method using the remainder system. Explanatory drawing for explaining the distance calculation method using the remainder system. Explanatory drawing which shows an example of transmitting three transmitted waves having different angular frequencies with a distance on a horizontal axis and a phase on a vertical axis. Explanatory drawing for explaining the method of selecting the correct distance by the amplitude observation of the detected signal. The flowchart for demonstrating the 1st Embodiment. Explanatory drawing for demonstrating 1st Embodiment. Explanatory drawing for demonstrating 1st Embodiment. Explanatory drawing for demonstrating 1st Embodiment. Explanatory drawing for demonstrating 1st Embodiment. Explanatory drawing for demonstrating 1st Embodiment. Explanatory drawing for demonstrating 1st Embodiment. Explanatory drawing for demonstrating an eight-fold alternation sequence. The explanatory view which shows the transmission sequence for shortening a communication time in 1st Embodiment. The explanatory view which shows the transmission sequence for shortening a communication time in 1st Embodiment. The timing chart corresponding to the sequence of FIG. Explanatory drawing for demonstrating the effect of 1st Embodiment. Explanatory drawing for demonstrating the effect of 1st Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment of this invention. The timing chart corresponding to the sequence of FIG. 21. Explanatory drawing for demonstrating the 3rd Embodiment of this invention. Explanatory drawing for demonstrating the 3rd Embodiment of this invention. Explanatory drawing for demonstrating the 4th Embodiment of this invention. Explanatory drawing for demonstrating the 4th Embodiment of this invention. Explanatory drawing for demonstrating the 5th Embodiment of this invention. Explanatory drawing for demonstrating the 5th Embodiment of this invention. Explanatory drawing for demonstrating the 5th Embodiment of this invention. Explanatory drawing which shows the 9th Embodiment of this invention. Explanatory drawing which shows the 9th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First Embodiment)
FIG. 1 is a block diagram showing a distance measuring system using the distance measuring device according to the first embodiment of the present invention.

In this embodiment, an example will be described in which a phase detection method using a non-modulation carrier is adopted, and a communication type ranging is adopted in which the distance between each device is obtained by communication between the devices. In a general phase detection method using a reflected wave, the distance that can be measured is relatively short as described above. Therefore, in the present embodiment, the communication type distance measurement for communicating between the devices is adopted. However, since each transmitter of each device operates independently, the initial phases of the radio waves transmitted from each transmitter are different from each other, and the conventional phase detection method in which the distance is obtained by the phase difference requires an accurate distance. Can't. Therefore, in the present embodiment, as will be described later, by transmitting the phase information obtained by the reception of one device to the other device, it is possible to obtain an accurate distance in the other device.

This embodiment makes it possible to shorten the communication time required for distance measurement when adopting such a distance measurement technique, as in the case of a four-time alternation sequence described later. Hereinafter, the basic configuration of the communication type ranging technology adopted in the present embodiment will be described with reference to FIGS. 2A to 15.
<Basic configuration of communication type ranging technology>
First, in order to explain the distance measurement by the phase detection method adopted in the present embodiment, the principle of the distance measurement by the phase detection method using the reflected wave and its problems are referred to with reference to the explanatory diagrams of FIGS. 2A and 2B. Will be described.
(About phase detection method)
In the phase detection method, signals of two frequencies deviated _{from the central angular frequency ω C1} by the angular frequency ± ω _{B1 are transmitted for distance measurement.} In a distance measuring device that uses reflected waves, a transmitter and a receiver are provided in the same housing, and the transmitted signal (radio wave) emitted from the transmitter is reflected by an object to receive the reflected wave.

2A and 2B show this state, and show that the radio wave emitted from the transmitter T is reflected by the wall W and received by the receiver S. For the sake of simplicity, it is assumed that the phase of the radio wave does not change in the reflection on the wall W.

As shown in FIG. 2A, the angular frequency of the radio wave emitted from the transmitter is ω _C1 + ω _B1 , and the initial phase is θ _1H . In this case, the transmission signal (transmission wave) tx1 (t) emitted from the transmitter is represented by the following equation (1).
tx1 (t) = cos {(ω _C1 + ω _B1 ) t + θ _1H }… (1)
This transmission signal reaches an object (wall W) separated from the transmitter by a distance R [m] with a delay time τ ₁ , is reflected, and is received at the receiver. Since the speed of radio waves is the speed of light c (= 3 × 10 ⁸ m / s), τ ₁ = (R / c) [seconds]. Signal received by the receiver has received the delay 2.tau ₁ relative to firing signals. Therefore, the received signal (received wave) rx1 (t) of the receiver is represented by the following equations (2) and (3).
rx1 (t) = cos {(ω _C1 + ω _B1 ) t + θ _1H −θ _{2 × Hτ1} )}… (2)
θ _{2 × Hτ1} = (ω _C1 + ω _B1 ) 2τ ₁ … (3)
That is, the transmission signal is received by the receiver with a phase shift caused by _{the multiplication result (θ 2 × Hτ1} ) of the delay time and the transmission angular frequency.

Similarly, as shown in FIG. 2B, the transmission signal tx1 (t) and the reception signal rx1 (t) when the _{angular frequencies ω C1- ω B1} are used have the following (4) to (6 _{) with the initial phase set to θ 1L.} ) Is shown in the equation.
tx1 (t) = cos {(ω _{C1- ω B1} ) t + θ _1L }… (4)
rx1 (t) = cos {(ω _{C1- ω B1} ) t + θ _1L −θ _{2 × Lτ1} }… (5)
θ _{2 × Lτ1} = (ω _{C1 -ω B1} ) 2τ ₁ … (6)
Let _{θ H1} (t) be the amount of phase shift that occurs before the transmission signal with angular frequency ω _C1 + ω _{B1 is received, and θ L1 be the} amount of phase shift that occurs before the transmission signal with _{angular frequency ω C1- ω B1 is received.} Assuming (t), the difference between the phase shifts of the two received waves is given by the following equation (7) obtained by subtracting the equation (6) from the equation (3).
θ _H1 (t) −θ _L1 (t) = (θ _{2 × Hτ1} −θ _{2 × Lτ1} ) = 2ω _B1 × 2τ ₁ … (7)
Here, τ ₁ = R / c. Since the difference frequency ω _B1 is known, if the difference between the phase shift amounts of the two received waves is measured, the distance R can be obtained from the measurement result.
R = c × (θ _{2 × Hτ1} −θ _{2 × Lτ1} ) / (4ω _B1 )
Can be calculated.

By the way, in the above description, the distance R is calculated by considering only the phase information. Next, a consideration will be given to the amplitude when a transmitted wave having an angular frequency of ω _C1 + ω _{B1 is used.} When the transmitted wave represented by the above equation (1) reaches an object separated by a distance R, it is delayed by a delay amount τ ₁ = R / c, and the amplitude is attenuated by the attenuation L1 corresponding to the distance R. The received wave rx2 (t) shown in Eq. 8) is obtained.
rx2 (t) = L ₁ × cos {(ω _C1 + ω _B1 ) t + θ _1H − (ω _C1 + ω _B1 ) τ ₁ }… (8)
Further, the transmitted wave receives an _{attenuated LRFL when reflected from the object.} The reflected wave tx2 (t) in the object is given by the following equation (9).
tx2 (t) = L _RFL × L ₁ × cos {(ω _C1 + ω _B1 ) t + θ _1H − (ω _C1 + ω _B1 ) τ ₁ }… (9)
As for the received signal received by the receiver, rx1 (t) is delayed by the delay amount τ ₁ = R / c [seconds] from the object, and the amplitude is attenuated by the attenuation L1 according to the distance R. ) Is expressed by the formula.
rx1 (t) = L ₁ × L _RFL × L ₁ × cos {(ω _C1 + ω _B1 ) t + θ _1H -2 (ω _C1 + ω _B1 ) τ ₁ }… (10)
In this way, the transmitted signal from the transmitter is attenuated by _{L 1} × L _RFL × L _{1 by the time it reaches the receiver.} The signal amplitude that can be emitted from the transmitter in distance measurement must follow the Radio Law according to the applicable frequency. For example, in a specific frequency of the 920 MHz band, there is a limitation that the transmission signal power is suppressed to 1 mW or less. From the viewpoint of the signal-to-noise ratio of the received signal, it is necessary to keep the attenuation received from transmission to reception small in order to measure the distance accurately. However, as described above, since the attenuation is relatively large in the distance measurement using the reflected wave, the distance that can be accurately measured is short.

Therefore, as described above, in the present embodiment, the attenuation is reduced by _{L RFL} × L ₁ minute by transmitting and receiving signals from each other between the two devices without using the reflected wave. , The distance that can be accurately measured is expanded.

However, the two devices are separated from each other by a distance R and cannot share the same reference signal, and it is generally difficult to synchronize the transmitted signal with the locally oscillated signal used for reception. That is, not only is the signal frequency shifted between the two devices, but the initial phase is unknown. Hereinafter, problems in distance measurement when such an asynchronous transmitted wave is used will be described.
(Issues in the case of asynchronous)
In the distance measuring system of the present embodiment, two devices (first device and second device) that asynchronously emit carrier signals (transmission signals) are arranged at the positions of each object when measuring a distance between two objects. , The distance R between these two devices is obtained. In the present embodiment, the first apparatus _{transmits carrier signals having two frequencies deviated from the central angle frequency ω C1} by the angular frequency ± ω _B1 , and the second apparatus transmits the carrier signals having an angular frequency ± ω _{B2 from the central angle frequency ω C2.} It transmits carrier signals of two frequencies that are slightly offset.

3A and 3B are explanatory views illustrating a problem when the above-mentioned phase detection method is simply applied between the two devices A1 and A2. First, it is assumed that the transmission signal of the device A1 is received by the device A2. The local oscillator of the device A1 is the two-wave carrier angular frequency of the transmitted wave is ω _{C1 +} ω _B1 and omega _C1 - [omega] _B1 generates a frequency signal necessary for generating heterodyne scheme, the device A1 This angular frequency Two transmitted waves of are transmitted. Further, the local oscillator of the device A2 generates a frequency signal necessary for the angular frequency of the transmitted wave is generated by heterodyne scheme two waves ω _{C2 +} ω _B2 and omega _C2 - [omega] _B2, device A2 is a local oscillator Heterodyne reception shall be performed using the signal from.

Here, the distance between the transmitter / receiver is set to 2R in order to correspond to the case where the reflected wave described above is used. The initial phase of the transmission signal of the transmission signal and the angular frequency omega _C1 - [omega] _B1 of the angular frequency omega _C1 + omega _B1 from device A1, respectively theta _IH, and theta _1L. Furthermore, the angular frequency omega _C2 + omega _B2 of device A2, omega _C2 - [omega] 2 two signal initial phase respectively theta _2H of _B2, and theta _2L.

First, consider the phase of the transmitted signal having an angular frequency of ω _C1 + ω _B1. The transmission signal represented by the above equation (1) is output from the device A1. The received signal rx2 (t) in the device A2 is given by the following equation (11).
rx2 (t) = cos {(ω _C1 + ω _B1 ) t + θ _1H −θ _{2 × Hτ1} }… (11)
In the device A2, the received wave is in-phase by multiplying the two signals cos {(ω _C2 + ω _B2 ) t + θ _2H } and sin {(ω _C2 + ω _B2 ) t + θ _2H } and the received wave of the equation (11). It is separated into a component (I signal) and an orthogonal component (Q signal). The phase of the received wave (hereinafter, referred to as the detected phase or simply the phase) can be easily obtained from the I and Q signals. That is, the detection phase θ _H1 (t) is expressed by the following equation (12). In the following equation (12), _{the term of the harmonic near the angular frequency ω C1} + ω _C2 is omitted because it is removed at the time of demodulation.
θ _H1 (t) = tan ^-1 (Q (t) / I (t)) =-{(ω _{C1- ω C2} ) t + (ω _{B1- ω B2} ) t + θ _1H −θ _2H −θ _{2 × Hτ1} }… (12)
_{Similarly, when the transmission signal of the angular frequency ω C1- ω B1} is transmitted from the device A1, the _{detection phase θ L1} (t) obtained from the I and Q signals obtained by the device A2 is given by the following equation (13). Be done. In the following equation (13), _{the term of the harmonic near the angular frequency ω C1} + ω _C2 is omitted because it is removed at the time of demodulation.
θ _L1 (t) = tan ^-1 (Q (t) / I (t)) =-{(ω _{C1 -ω C2} ) t- (ω _{B1 -ω B2} ) t + θ _1L −θ _2L −θ _{2 × Lτ1} } … (13)
The phase difference between these two detected phases (hereinafter, referred to as the detected phase difference or simply the phase difference) θ _H1 (t) −θ _L1 (t) is expressed by the following equation (14).
θ _H1 (t) −θ _L1 (t) =-2 _{(ω B1- ω B2} ) t + (θ _1H −θ _1L ) − (θ _2H −θ _2L ) + (θ _{2 × Hτ1} −θ _{2 × Lτ1} )… (14)
In the conventional ranging device using the reflected wave, since the device A1 and the device A2 are the same device and share the local oscillator, the following equations (15) to (17) are satisfied. ..
ω _B1 = ω _B2 … (15)
θ _1H = θ _2H … (16)
θ _1L = θ _2L … (17)
When the equations (15) to (17) are satisfied, the equation (14) becomes equal to the equation (7) described above, and the apparatus is based on the phase difference obtained by the I, Q demodulation process for the received signal in the apparatus A2. The distance R between A1 and the device A2 can be calculated.

However, since the device A1 and the device A2 are provided apart from each other and the local oscillators operate independently of each other, the above equations (15) to (17) are not satisfied. In this case, unknown information such as the difference in the initial phase is included in the equation (14), and the distance cannot be calculated correctly.
(Basic ranging method of the embodiment)
The above-mentioned two angular frequency signals transmitted by the first device are received by the second device to obtain the phase of each signal, and the above-mentioned two angular frequency signals transmitted by the second device are received by the first device. To find the phase of each signal. Further, phase information is transmitted from one of the first device and the second device to the other. In the present embodiment, as will be described later, the first is by adding the phase difference of the two signals obtained by the reception of the first device and the phase difference of the two signals obtained by the reception of the second device. The distance R between the device and the second device is calculated. The phase information may be I, Q signals, phase information obtained from I, Q signals, or phase difference information obtained from two signals having different frequencies. May be good.
(composition)
In FIG. 1, the first device 1 (hereinafter, also referred to as device 1) and the second device 2 (hereinafter, also referred to as device 2) are arranged apart by a distance R. At least one of the device 1 and the device 2 is movable, and the distance R changes with this movement. The device 1 is provided with a control unit 11. The control unit 11 controls each unit of the device 1. The control unit 11 may be configured by a processor using a CPU or the like and operate according to a program stored in the memory 12 to control each unit.

The oscillator 13 is controlled by the control unit 11 and generates oscillation signals (local signals) of two frequencies based on the built-in reference oscillator. Each oscillation signal from the oscillator 13 is supplied to the transmission unit 14 and the reception unit 15. The angular frequency of the oscillation signal by the oscillator 13 is generated, is set to the angular frequency required to generate the two-wave transmission section 14 ω _{C1 +} ω _B1 and omega _C1 - [omega] _B1 as the angular frequency of the transmitted wave. When the oscillator 13 is composed of a plurality of oscillators, each of these oscillators oscillates in synchronization with the output of a common reference oscillator.

The transmitter 14 can be configured by, for example, a quadrature modulator. Transmitting section 14 is controlled by the control unit 11, so that it can be angular frequency transmission signal and the angular frequency of ω _{C1 +} ω _B1 outputs two transmission waves of the transmission signal of omega _C1 - [omega] _B1 There is. The transmitted wave from the transmitting unit 14 is supplied to the antenna circuit 17.

The antenna circuit 17 has one or more antennas, and can transmit the transmitted wave from the transmitting unit 14. Further, the antenna circuit 17 receives the transmitted wave from the device 2 described later and supplies the received signal to the receiving unit 15.

The receiving unit 15 can be configured by, for example, an orthogonal demodulator. The receiving unit 15 is controlled by the control unit 11 to receive and demodulate the transmitted wave from the device 2 by using the signals from the oscillator 13 having, for example, ω _{C1 and ω B1 angular frequencies, and the in-phase component of the received wave.} (I signal) and orthogonal component (Q signal) can be separated and output.

The configuration of the device 2 is the same as that of the device 1. That is, the second device is provided with a control unit 21. The control unit 21 controls each unit of the device 2. The control unit 21 may be configured by a processor using a CPU or the like and operate according to a program stored in the memory 22 to control each unit.

The oscillator 23 is controlled by the control unit 21 and generates oscillation signals of two frequencies based on the built-in reference oscillator. Each oscillation signal from the oscillator 23 is supplied to the transmission unit 24 and the reception unit 25. The angular frequency of the oscillation signal by the oscillator 23 is generated, is set to the angular frequency required to generate the two waves ω _{C2 +} ω _B2 and omega _C2 - [omega] _B2 as the angular frequency of the transmission wave of the transmitter 24. When the oscillator 23 is composed of a plurality of oscillators, each of these oscillators oscillates in synchronization with the output of a common reference oscillator.

The transmitter 24 can be configured by, for example, a quadrature modulator. Transmitter 24 is controlled by the control unit 21, so that it can transmit signals and the angular frequency of the angular frequency omega _{C2 +} omega _B2 outputs two transmission waves of the transmission signal of omega _C2 - [omega] _B2 There is. The transmitted wave from the transmitting unit 24 is supplied to the antenna circuit 27.

The antenna circuit 27 has one or more antennas, and can transmit the transmitted wave from the transmitting unit 24. Further, the antenna circuit 27 receives the transmitted wave from the device 1 and supplies the received signal to the receiving unit 25.

The receiving unit 25 can be configured by, for example, an orthogonal demodulator. The receiving unit 25 is controlled by the control unit 21 to receive and demodulate the transmitted wave from the device 1 by using the signals from the oscillator 23, for example, having angular frequencies of ω _C2 and ω _{B2, and the in-phase component of the received wave.} (I signal) and orthogonal component (Q signal) can be separated and output.

FIG. 4 is a circuit diagram showing an example of a specific configuration of the transmitting unit 14 and the receiving unit 15 in FIG. Further, FIG. 5 is a circuit diagram showing an example of a specific configuration of the transmitting unit 24 and the receiving unit 25 in FIG. 4 and 5 show an image suppression type transmitter / receiver, but the present invention is not limited to this configuration.

The configuration of the image suppression method is known, and its feature is that when demodulating a higher angular frequency band centered on _{the local angular frequency for high frequency, ω C1} or ω _{C2, the lower angular frequency band is used.} The signal is attenuated, and when demodulating the lower angular frequency band, the signal in the higher angular frequency band is attenuated. This filtering effect is due to signal processing. The same applies to transmission. When demodulating a higher angular frequency band centered on ω _C1 or ω _{C2 , use sin (ω B1} t + θ _B1 ) or sin (ω _B2 t + θ _B2 ) in FIGS. 4 and 5 to obtain a lower angular frequency band. When demodulating, -sin (ω _B1 t + θ _B1 ) or -sin (ω _B2 t + θ _B2 ) is used in FIGS. 4 and 5. The frequency band to be demodulated is determined by this change in polarity. Note that θ _B1 and θ _B2 represent the phase of each angular frequency at t = 0, that is, the initial phase. The same applies to _{θ C1} and θ _C2.

In the image suppression type receiver, _{the term of harmonics near the angular frequency ω C1} + ω _C2 is removed at the time of demodulation, so this term is omitted in the following calculation.

The transmitter 14 is composed of multipliers TM01 to TM04, TM11, TM12 and adders TS01, TS02, TS11. Input signal _{I TX1} is supplied to the multiplier TM01, TM03, the input signal _{Q TX1} is supplied to the multiplier TM02, TM04. The multipliers TM01 and TM04 _{are given cos (ω B1} t + θ _B1 ) from the oscillator 13, and the multipliers TM02 and TM03 are given either _{± sin (ω B1} t + θ _{B1) from the oscillator 13.}

The multipliers TM01 to TM04, TM11, and TM12 each multiply two inputs, the adder TS01 adds the multiplication results of the multipliers TM01 and TM02 and outputs them to the multiplier TM11, and the adder TS02 is the multiplication result of the multiplier TM03. The multiplication result of TM04 is subtracted from and output to the multiplier TM12.

The multiplier TM11 _{is given cos (ω C1} t + θ _C1 ) from the oscillator 13, and the multiplier TM12 is given sin (ω _C1 t + θ _C1 ) from the oscillator 13.

The multipliers TM11 and TM12 each multiply two inputs and give the multiplication result to the adder TS11. The adder TS11 adds the outputs of the multipliers TM11 and TM12 and outputs the addition result as a transmission wave tx1.

The receiving unit 15 is composed of multipliers RM11 to RM16 and adders RS11 and RS12. The transmitted wave of the device 2 is input to the multipliers RM11 and RM12 as a received signal rx1 via the antenna circuit 17. _{Oscillation signals having an angular frequency of ω C1} and phases different from each other by 90 degrees are given to the multipliers RM11 and RM12 from the oscillator 13. The multiplier RM11 multiplies two inputs and gives the multiplication result to the multipliers RM13 and RM14, and the multiplier RM12 multiplies the two inputs and gives the multiplication result to the multipliers RM15 and RM16.

An oscillation signal having an angular frequency (baseband local angular frequency) of ω _{B1 is given to the multipliers RM13 and RM15 from the oscillator 13.} The multiplier RM13 multiplies two inputs and gives the multiplication result to the adder RS11, and the multiplier RM14 multiplies the two inputs and gives the multiplication result to the adder RS12.

Further, the multipliers RM14 and RM16 are given an oscillation signal _{having an angular frequency of ω B1} from the oscillator 13 or a signal orthogonal to the oscillation signal of _{ω B1 given to the multiplier RM 13 by an inverted signal thereof.} The multiplier RM14 multiplies two inputs and gives the multiplication result to the adder RS12, and the multiplier RM16 multiplies the two inputs and gives the multiplication result to the adder RS11.

The adder RS11 subtracts the outputs of the multipliers RM13 and RM16 and outputs the subtraction result as an I signal. Further, the adder RS12 adds the outputs of the multipliers RM14 and RM15 and outputs the addition result as a Q signal. The I and Q signals from the receiving unit 15 are supplied to the control unit 11.

The circuits of FIGS. 4 and 5 show the same circuit. That is, in FIG. 5, the configurations of the multipliers TM05 to TM08, TM21, TM22, RM21 to RM26 and the adders TS05, TS06, TS21, RS21, RS22 are the multipliers TM01 to TM04, TM11, TM12, RM11 of FIG. 4, respectively. The configuration is the same as that of the RM16 and the adders TS01, TS02, TS11, RS11, and RS12. Since the frequency and phase of the oscillation signal of the oscillator 23 are different from those of the oscillator 13, in FIG. 5, _ITX2 and _QTX2 are supplied as inputs, and the local angle for the baseband is replaced with the angular frequency ω _{B1 in FIG.} The only difference is that the frequency ω _B2 is input and ω _C2 is input instead of the angular frequency ω _{C1 in FIG.} The I and Q signals from the receiving unit 25 are supplied to the control unit 21.

In the present embodiment, the control unit 11 of the apparatus 1 controls the transmission section 14, the angular frequency to transmit two transmission waves of omega _{C1 +} omega _B1 and omega _C1 - [omega] _B1 through the antenna circuit 17 ..

On the other hand, the control unit 21 of the apparatus 2 controls the transmission section 24, the angular frequency to transmit two transmission waves of omega _C2 + omega _B2 and omega _C2 - [omega] _B2 via the antenna circuit 27.

The control unit 11 of the device 1 controls the receiving unit 15 to receive the two transmitted waves from the device 2 and acquire the I and Q signals, respectively. The control unit 11 obtains the difference between the two phases obtained from the I and Q signals obtained from the two received signals, respectively.

Similarly, the control unit 21 of the device 2 controls the receiving unit 25 to receive the two transmitted waves from the device 1 and acquire the I and Q signals, respectively. The control unit 21 also obtains the difference between the two phases obtained from the I and Q signals obtained from the two received signals, respectively.

In the present embodiment, the control unit 11 of the device 1 gives the phase information based on the acquired I and Q signals to the transmission unit 14 to transmit the phase information. As described above, the phase information may be, for example, an I or Q signal obtained from two received signals or given a predetermined initial value, and the phase information obtained from these I and Q signals may be used. It may be information on the difference between these phases.

For example, the control unit 11 may transmit the phase information by generating I and Q signals based on the phase information of the received signal _{having an angular frequency of ω B2 and supplying them to the multipliers TM11 and TM12, respectively.} ..

The control unit 11, when the output of the oscillation signal of the angular frequency omega _B1, I the angular frequency obtained by adding the phase information of the received signal of the initial phase to the angular frequency omega _B2 of the oscillation signal of the omega _B1, generating a Q signal Then, the phase information may be transmitted by supplying the multipliers TM11 and TM12, respectively.

The receiving unit 25 of the device 2 receives the phase information transmitted by the transmitting unit 14 via the antenna circuit 27. The receiving unit 25 demodulates the received signal to obtain I and Q signals of phase information. The I and Q signals are supplied to the control unit 21. The control unit 21 obtains a value including the phase difference acquired by the control unit 11 of the device 1 from the phase information from the reception unit 25. The control unit 21 as a calculation unit adds the phase difference obtained from the reception result of the reception unit 25 and the phase difference based on the phase information transmitted from the device 2 to the first device 1 and the second device 2. The distance R between and is calculated.

Although FIG. 1 shows an example in which both the first device 1 and the second device 2 have a function of transmitting phase information and a function of giving the received phase information to the control unit and calculating the distance R. It suffices that one of the first device 1 and the second device 2 has a function of transmitting phase information, and the other has a function of giving the received phase information to the control unit and calculating the distance R.
(Basic operation of communication type ranging)
Next, the operation in such communication type distance measurement will be described with reference to the flowchart of FIG. 6 by taking as an example the case where the device 2 calculates the distance. FIG. 6 shows the operation of the device 1 on the left side and the operation of the device 2 on the right side. In FIG. 6, the arrows connecting the steps of the devices 1 and 2 indicate that communication is performed between the devices 1 and 2. It should be noted that steps S4, S5, S14, and S15 are executed almost at the same time.

In step S1, the control unit 11 of the device 1 determines whether or not there is an instruction to start distance measurement, and if there is an instruction to start distance measurement, controls the oscillator 13 to start outputting a necessary oscillation signal. Further, the control unit 21 of the device 2 determines in step S11 whether or not there is an instruction to start distance measurement, and if there is an instruction to start distance measurement, controls the oscillator 23 to start outputting a necessary oscillation signal. ..

As will be described later, the control unit 11 ends the oscillation in step S9, and the control unit 21 ends the oscillation in step S20. The control of the start and end of the oscillation in the control units 11 and 21 indicates that the oscillation of the oscillators 13 and 23 is not stopped during the transmission and reception period for distance measurement, and the actual start and end of the oscillation are shown. The end timing is not limited to the flow shown in FIG. During the period in which the oscillations of the oscillators 13 and 23 continue, the initial phase of each of the oscillators 13 and 23 is not newly set.

The control unit 11 of the device 1 generates two transmission signals in step S3, and transmits these transmission signals as transmission waves from the antenna circuit 17 (step S4). Further, the control unit 21 of the device 2 generates two transmission signals in step S13, and transmits these transmission signals as transmission waves from the antenna circuit 27 (step S14).

It is assumed that the initial phase of the oscillation signal _{having a frequency of ω C1} output from the oscillator 13 of the device 1 _{is θ C1} , and the initial phase of the oscillation signal having a frequency of ω _B1 is θ _B1 . As described above, these initial phases θ _C1 and θ _B1 are not newly set as long as the oscillation of the oscillator 13 continues.

It is assumed that the initial phase of the oscillation signal _{having a frequency of ω C2} output from the oscillator 23 of the device 2 _{is θ C2} , and the initial phase of the oscillation signal having a frequency of ω _B2 is θ _B2 . These initial phases θ _C2 and θ _B2 are not newly set as long as the oscillation of the oscillator 23 continues.

Assuming simultaneous transmission and simultaneous reception of two frequencies, the device 1 requires two wireless units of FIG. 4 and the device 2 requires two wireless units of FIG. Alternatively, a radio such as a superheterodyne system is used. However, the same oscillator shall be used.
(Transmission and reception of transmitted waves with angular frequencies of ω _C1 + ω _{B1 from device 1)}
Now, _assuming that I TX1 = 1, Q _TX1 = 0, that is, an IQ signal having a radius of 1 and a phase of 0 degrees is given in FIG. from 1 angular frequency 2 transmission wave omega _C1 + omega _B1 and omega _C1 - [omega] _B1 is output. The transmission signal tx1 (t) having an angular frequency of ω _C1 + ω _B1 is represented by the following equation (18).
tx1 (t) = cos (ω _C1 t + θ _C1 ) cos (ω _B1 t + θ _B1 ) -sin (ω _C1 t + θ _C1 ) sin (ω _B1 t + θ _B1 )
= Cos {(ω _C1 + ω _B1 ) t + θ _C1 + θ _B1 }… (18)
Assuming that the distance between the devices 1 and 2 is R and the delay until the transmitted wave from the device 1 is received by the device 2 is τ ₁ , the received signal rx2 (t) of the device 2 is the following (19), It can be expressed by equation (20).
rx2 (t) = cos {(ω _C1 + ω _B1 ) (t−τ ₁ ) + θ _C1 + θ _B1 }
= Cos {(ω _C1 + ω _B1 ) t + θ _C1 + θ _B1 −θ _τH1 }… (19)
θ _τH1 = (ω _C1 + ω _B1 ) τ ₁ ... (20)
This received signal rx2 (t) is received by the antenna circuit 27 and supplied to the receiving unit 25. In the receiver of FIG. 5, the received signal rx2 (t) is input to the multipliers RM21 and RM22. Next, the signals at each node of the receiver of FIG. 5 are sequentially calculated. The outputs of the multipliers RM21, RM23, and RM24 are I ₁ (t), I ₂ (t), and I ₃ (t), respectively, and the outputs of the multipliers RM22, RM26, and RM25 are Q ₁ (t) and Q ₂ (respectively). Let t) and Q ₃ (t), and let the outputs of the adders RS21 and RS22 be I (t) and Q (t), respectively. These outputs are represented by the following equations (21) to (26).
I ₁ (t) = cos (ω _C2 t + θ _C2 ) × cos {(ω _C1 + ω _B1 ) t + θ _C1 + θ _B1 −θ _τH1 }… (21)
Q ₁ (t) = sin (ω _C2 t + θ _C2 ) × cos {(ω _C1 + ω _B1 ) t + θ _C1 + θ _B1 −θ _τH1 }… (22)
I ₂ (t) = I ₁ (t) × cos (ω _B2 t + θ _B2 )… (23)
Q ₂ (t) = Q ₁ (t) × sin (ω _B2 t + θ _B2 )… (24)
I ₃ (t) = I ₁ (t) × sin (ω _B2 t + θ _B2 )… (25)
Q ₃ (t) = Q ₁ (t) × cos (ω _B2 t + θ _B2 )… (26)
The output I (t) of the adder RS21 is I (t) = I ₂ (t) + Q ₂ (t), and the output Q (t) of the adder RS22 is Q (t) = I ₃ (t). -Q ₃ (t). _{The phase θ H1} (t) obtained from these I (t) and Q (t) is shown in (27) below.
θ _H1 (t) = tan ^-1 (Q (t) / I (t)) =-{(ω _{C1- ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2- θ _τH1 }… (27)
(Transmission and reception of transmitted waves with angular frequencies of ω _C2 + ω _{B2 from device 2)}
Similarly, in FIG. 5, I _TX2 = 1 and Q _TX2 = 0. In this case, the device after ₂ signal tx2 (t) is the delay τ of the angular frequency omega _C2 + omega _B2 transmitted from the 2, when received by the apparatus 1, I (t) to be detected by the device 1, Q (t _{) Find the} phase θ H2 (t) obtained from the signal.
tx2 (t) = cos (ω _C2 t + θ _C2 ) cos (ω _B2 t + θ _B2 ) -sin (ω _C2 t + θ _C2 ) sin (ω _B2 t + θ _B2 )
= Cos {(ω _C2 + ω _B2 ) t + θ _C2 + θ _B2 }… (28)
rx1 (t) = cos {(ω _C2 + ω _B2 ) (t−τ ₂ ) + θ _C2 + θ _B2 }
= Cos {(ω _C2 + ω _B2 ) t + θ _C2 + θ _B2 −θ _τH2 }… (29)
θ _τH2 = (ω _C2 + ω _B2 ) τ ₂ … (30)
This received signal rx1 (t) is received by the antenna circuit 17 and supplied to the receiving unit 15. In the receiver of FIG. 4, the received signal rx1 (t) is input to the multipliers RM11 and RM12. Next, the signals at each node of the receiver of FIG. 4 are sequentially calculated. The outputs of the multipliers RM11, RM13, and RM14 are I ₁ (t), I ₂ (t), and I ₃ (t), respectively, and the outputs of the multipliers RM12, RM16, and RM15 are Q ₁ (t) and Q ₂ (respectively). Let t) and Q ₃ (t), and let the outputs of the adders RS11 and RS12 be I (t) and Q (t), respectively. These outputs are represented by the following equations (31) to (36).
I ₁ (t) = cos (ω _C1 t + θ _C1 ) × cos {(ω _C2 + ω _B2 ) t + θ _C2 + θ _B2 −θ _τH2 }… (31)
Q ₁ (t) = sin (ω _C1 t + θ _C1 ) × cos {(ω _C2 + ω _B2 ) t + θ _C2 + θ _B2 −θ _τH2 }… (32)
I ₂ (t) = I ₁ (t) × cos (ω _B1 t + θ _B1 )… (33)
Q ₂ (t) = Q ₁ (t) × sin (ω _B1 t + θ _B1 )… (34)
I ₃ (t) = I ₁ (t) × sin (ω _B1 t + θ _B1 )… (35)
Q ₃ (t) = Q ₁ (t) × cos (ω _B1 t + θ _B1 )… (36)
The output I (t) of the _{adder RS11 is I (t) = I 2} (t) + Q ₂ (t), and the output Q (t) of the adder RS12 is Q (t) = I ₃ (t). -Q ₃ (t). _{The phase θ H2} (t) = tan ^-1 (Q (t) / I (t)) obtained from these I (t) and Q (t) is shown in (37) below.
θ _H2 (t) = (ω _{C1 -ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2 + θ _τH2 … (37)
(Transmission and reception of transmitted waves with angular frequencies of ω _{C1- ω B1 from device 1)}
Next, the same calculation is performed on the signal tx1 (t) of the _{angular frequency ω C1- ω B1} transmitted from the device 1.
tx1 (t) = cos (ω _C1 t + θ _C1 ) cos (ω _B1 t + θ _B1 ) + sin (ω _C1 t + θ _C1 ) sin (ω _B1 t + θ _B1 )
= Cos {(ω _{C1- ω B1} ) t + θ _C1- θ _B1 }… (38)
Will be. Since the distance between the device 1 and the device 2 is R and the delay time is τ ₁ , the received signal rx2 (t) in the device 2 is given by the following equations (39) and (40).
rx2 (t) = cos {(ω _{C1- ω B1} ) (t-τ ₁ ) + θ _C1- θ _B1 }
= Cos {(ω _{C1- ω B1} ) t + θ _C1- θ _B1- θ _τL1 }… (39)
θ _τL1 = (ω _{C1 -ω B1} ) τ ₁ ... (40)
The signals of each node of the device 2 can be represented by the following equations (43) to (47).
I ₁ (t) = cos (ω _C2 t + θ _C2 ) × cos {(ω _{C1- ω B1} ) t + θ _C1- θ _B1- θ _τL1 }… (41)
Q ₁ (t) = sin (ω _C2 t + θ _C2 ) × cos {(ω _{C1- ω B1} ) t + θ _C1- θ _B1- θ _τL1 }… (42)
I ₂ (t) = I ₁ (t) × cos (ω _B2 t + θ _B2 )… (43)
Q ₂ (t) = Q ₁ (t) × −sin (ω _B2 t + θ _B2 )… (44)
I ₃ (t) = I ₁ (t) × −sin (ω _B2 t + θ _B2 )… (45)
Q ₃ (t) = Q ₁ (t) × cos (ω _B2 t + θ _B2 )… (46)
Detected by device 2 from I (t) = I ₂ (t) -Q ₂ (t) obtained from the adder RS21 and Q (t) = I ₃ (t) + Q _{3 (t) obtained from the adder RS22.} The phase θ _L1 (t) = tan ^-1 (Q (t) / I (t)) to be used is given by the following equation (47).
^{_{θ L1 (t) = tan -1}} (Q (t) / I (t)) = - {(ω C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ _B2 ) −θ _τL1 }… (47)
(Transmission and reception of transmitted waves with angular frequencies of ω _{C2- ω B2 from device 2)}
Similarly, when the signal tx2 (t) of the _{angular frequency ω C2- ω B2} transmitted from the device 2 _{is received by the device 1 after the delay τ2} , I (t) and Q (t) detected by the device 1 are detected. _{) Find the} phase θ L2 (t) obtained from the signal.
tx2 (t) = cos (ω _C2 t + θ _C2 ) cos (ω _B2 t + θ _B2 ) + sin (ω _C2 t + θ _C2 ) sin (ω _B2 t + θ _B2 )
= Cos {(ω _{C2- ω B2} ) t + θ _C2- θ _B2 }… (48)
rx1 (t) = cos {(ω _{C2- ω B2} ) (t-τ ₂ ) + θ _C2- θ _B2 }
= Cos {(ω _{C2- ω B2} ) t + θ _C2- θ _B2- θ _τL2 }… (49)
θ _τL2 = (ω _{C2 -ω B2} ) τ ₂ … (50)
The signals of each node of the device 1 can be represented by the following equations (53) to (57).
I ₁ (t) = cos (ω _C1 t + θ _C1 ) × cos {(ω _{C2- ω B2} ) t + θ _C2- θ _B2- θ _τL2 }… (51)
Q ₁ (t) = sin (ω _C1 t + θ _C1 ) × cos {(ω _{C2- ω B2} ) t + θ _C2- θ _B2- θ _τL2 }… (52)
I ₂ (t) = I ₁ (t) × cos (ω _B1 t + θ _B1 )… (53)
Q ₂ (t) = Q ₁ (t) × −sin (ω _B1 t + θ _B1 )… (54)
I ₃ (t) = I ₁ (t) × −sin (ω _B1 t + θ _B1 )… (55)
Q ₃ (t) = Q ₁ (t) × cos (ω _B1 t + θ _B1 )… (56)
Detected by device 1 from I (t) = I ₂ (t) -Q ₂ (t) obtained from the adder RS11 and Q (t) = I ₃ (t) + Q _{3 (t) obtained from the adder RS12.} The phase θ _L2 (t) = tan ^-1 (Q (t) / I (t)) to be used is given by the following equation (57).
_{θ L2 (t) = (ω} C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) + θ τL2 ... (57)
The control unit 11 of the device 1 acquires the I and Q signals received by the receiving unit 15 in step S6 of FIG. 6, and in step S7, the phase θ _τH2 (t) shown in the above equations (37) and (57). And θ _τL2 (t) are calculated. Further, the control unit 21 of the device 2 acquires the I and Q signals received by the receiving unit 25 in step S16 of FIG. 6, and in step S17, the phase θ _τH1 (Phase θ τH1) shown in the above equations (27) and (47). t) and θ _τL1 (t) are calculated.

The control unit 11 gives the acquired phase information to the transmission unit 14 to transmit it (step S8). For example, the control unit 11 supplies I and Q signals based on phase information in place of the oscillation signals supplied to the multipliers TM11 and TM12 in FIG. In addition, another transmitter for transmitting the phase information may be used.

The control unit 21 of the device 2 receives the phase information from the device 1 in step S18. As described above, the phase information may be I, Q signals from the receiving unit 15 of the device 1, phase information obtained from the I, Q signals, or these. It may be information on the phase difference.

In step S19, the control unit 21 performs the calculation of the following equation (58) to calculate the distance. The following equation (58) adds the difference between the equation (27) and the equation (47) and the difference between the equation (37) and the equation (57).
{Θ _H1 (t) -θ _L1 (t)} + {θ _H2 (t) -θ _L2 (t)} = (θ _τH1- θ _τL1 ) + (θ _τH2- θ _τL2 )… (58)
Further, the following equations (59) and (60) are established.
θ _τH1 −θ _τL1 = (ω _C1 + ω _B1 ) τ ₁ − (ω _{C1- ω B1} ) τ ₁
= 2ω _B1 τ ₁ … (59)
_{θ τH2 -θ τL2 = (ω C2} + ω B2) τ 2 - (ω C2 -ω B2) τ 2
= 2ω _B2 τ ₂ … (60)
_{Further, since the delays τ 1} and τ ₂ of the radio waves between the devices 1 and 2 are the same regardless of the traveling direction, the following equation (61) can be obtained from the equations (58) to (60).
{Θ _H1 (t) -θ _L1 (t)} + {θ _H2 (t) -θ _L2 (t)} = (θ _τH1- θ _τL1 ) + (θ _τH2- θ _τL2 )
= 2 × (ω _B1 + ω _B2 ) τ ₁ … (61)
Since τ ₁ = (R / c), the above equation (61) shows the two-frequency phase difference due to the I and Q signals detected by the device 2 and the two-frequency phase difference due to the I and Q signals detected by the device 1. It is shown that a value proportional to twice the distance R can be obtained by the addition of. _{The angular frequency ω B1} by the oscillator 13 of the device 1 and the _{angular frequency ω B2} by the oscillator 13 of the device 2 can generally be matched with an error on the order of several tens of ppm. Therefore, the calculation of the distance R by the above equation (61) can be obtained with a resolution of at least about 1 m or more.

The control unit 11 stops the oscillator 13 in step S9, and the control unit 21 stops the oscillator 23 in step S20. As described above, the control units 11 and 21 may continue the oscillation during the transmission / reception period in steps S4, S5, S14, and S15, and the start and end timings of the oscillations of the oscillators 13 and 23 are shown in FIG. It is not limited to the example.
(Calculation of distance by remainder of 2π)
By the way, when the phase difference detected by the device 1 and the device 2 is added, the result may be a negative value or may be larger than 2π [rad]. In this case, the correct distance R with respect to the detection phase can be obtained by taking a remainder of 2π.

7 and 8 are explanatory views for explaining a distance calculation method using a remainder system.

For example, when R = 11 m and ω _B1 = ω _B2 = 2π × 5 MHz, the detected phase difference Δθ ₁₂ obtained by the device 1 and the detected phase difference Δθ ₂₁ obtained by the device 2 are shown in the following equation (62) and 21 respectively. It shall be as shown in equation (63).
Δθ ₁₂ = θ _τH1 −θ _τL1 = -1.8849 [rad]… (62)
Δθ ₂₁ = θ _τH2 −θ _τL2 = −6.0737 [rad]… (63)
From the above equation (61), the following equation (61a) can be obtained.

(1/2) [{Δθ ₁₂ } + {Δθ ₂₁ }] = (ω _B1 + ω _B2 ) (R / c)… (61a)
FIG. 7 shows the phase relationship of the above equations (62) and (63). _{The phase of the sum of Δθ 21} indicated by the innermost arrow that rotates clockwise with respect to the phase 0 degree and Δθ ₁₂ indicated by the second arrow from the inside is indicated by the third arrow from the inside. The half angle of this phase is the phase of the thick line indicated by the outermost arrow.

From equation (61a), −0.3993 = (ω _B1 + ω _B2 ) (R / c). When this equation is solved, R = -19 m, and the detected phase difference is larger than −π (rad), so it can be seen that the distance cannot be calculated correctly.

Therefore, in the present embodiment, in such a case, as shown in FIG. 8, _{both Δθ 12} and Δθ ₂₁ are added by 2π to perform the calculation. _{That is, the phase of the sum of 2π + Δθ 21} indicated by the innermost arrow that rotates counterclockwise with respect to the phase 0 degree and 2π + Δθ ₁₂ indicated by the second arrow from the inside is indicated by the third arrow from the inside. It becomes. The half angle of this phase is the phase of the thick line indicated by the outermost arrow.

2π + (Δθ ₁₂ + Δθ ₂₁ ) / 2 = 2.3008, and R = 11m can be obtained from the equation (61a).

From the above, in the present embodiment, when adding the detected phase differences, the distance R may be obtained by taking a remainder of 2π. The method of using the remainder of 2π in the phase addition can be similarly applied to other embodiments.
(Selection from multiple distance candidates)
By the way, since it is not possible to detect a detection phase difference exceeding 2π, there are a plurality of distance candidates for the calculated detection phase difference. As a method of selecting the correct distance from a plurality of distance candidates, there are a method of transmitting three transmitted waves having different angular frequencies and a method of determining by the received power.

FIG. 9 is an explanatory diagram showing an example in which three transmitted waves having different angular frequencies are transmitted with a distance on the horizontal axis and a phase on the vertical axis.

Since τ ₁ = (R / c), the following equation (64) can be obtained from the above equation (61).
(1/2) × {(θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 )} = (ω _B1 + ω _B2 ) × (R / c)… (64)
When the left-hand side referred to as theta _det, relationship between the distance R and theta _det is as shown in solid line in FIG. _{However, the sum θ det} of the detected phase differences calculated by the above equation (64) can take a value other than between −π (rad) and π (rad), but the sum θ _det of the detected phase differences is It is converted between −π (rad) and π (rad). This is because the phase angle is generally displayed within the range [-π (rad), π (rad)].

_{With reference to FIG. 9, there are R 1} , R ₂ , and R ₃ as distance candidates based on the sum of the detected phase differences θ _date . Here, the sum theta _det detected phase difference, the phase is the addition and subtraction result of obtained by transmission and reception of the transmission wave of angular frequency _{ω C1 + ω B1, ω C1} -ω B1, ω C2 + ω B2, ω C2 -ω B2 However, let us consider the results of phase addition and subtraction obtained by transmitting and receiving transmitted waves with angular frequencies ω _C1 + ω _B1 / Q and ω _C2 + ω _{B2 / Q.} However, Q is a rational number that satisfies the following equation (65).
Q> 1 ... (65)
The relationship between the detected phase at the new angular frequency and the distance R can be shown by the broken line in FIG. To select the correct distance from the candidate R ₁ to R ₃ of the distance refers to the results of the detected phase with a new angular frequency. That is, _{if θ det} 1 is detected, it is determined to _{be the distance R 1, and if θ det} 2 is detected, it is determined to _{be the distance R 2.} If the coverage range of radio waves is kept small, the above-mentioned inspection by phase folding is unnecessary. In the above description, transmission of three different frequencies has been described, but the same thing can be realized by transmitting three or more different frequencies.

Next, a method of selecting the correct distance by observing the amplitude of the signal detected with reference to the explanatory diagram of FIG. 10 will be described.

In the above (8), the amplitude attenuation L ₁ according to the distance R is described as attenuated, propagation attenuation generally free space is represented by the following (66) below.
L ₁ = (λ / 4πR) ² … (66)
Here, λ is a wavelength. According to (66) above, if the distance R is greater attenuation _{L 1} is large, the distance R is small if the attenuation _{L 1} is small. FIG. 10 showing the received power P on the vertical axis shows this relationship. 1 antenna gain of the transmitting and receiving, is given by assuming the transmission power _{P 0,} respectively received power _{P 2} at the receiving power _{P 1} and the distance _{R 2} at range _{R 1} is the following (67) or (68) below ..
P ₁ = (λ / 4πR ₁ ) ² × P ₀ … (67)
P ₂ = (λ / 4πR ₂ ) ² × P ₀ … (68)
Distinction between the distance R ₁ and R ₂ from the received power and the sum theta _det detected phase difference is possible.

In this case, reliable distance measurement is possible by using the remainder of 2π even in the phase addition.

As described above, in the basic distance measuring method of the present embodiment, signals having two angular frequencies are transmitted from the first device and the second device to the second device and the first device, respectively, and in the first and second devices, respectively. Find the two phases of two received signals, each with a different angular frequency. Then, the obtained phase information is transmitted from either one of the first device and the second device to the other. The device that received the phase information is the oscillator of the first device and the second device based on the addition result of the phase difference of the two received signals received by the first device and the phase difference of the two received signals received by the second device. Accurately calculate the distance between the first device and the second device regardless of the initial phase of. In this distance measuring system, accurate distance measurement is performed only by direct waves from the first device and the second device without using reflected waves, and the distance that can be measured can be expanded.

_{By the way, in the above description, assuming that the radio wave delays τ 1} and τ ₂ are the same in the above equation (58), the above equation (61) for obtaining the distance from the addition of the detected phase differences is obtained. However, this equation (58) is an example when the processing of transmitting and receiving is performed simultaneously in the devices 1 and 2.

However, due to the provisions of the Domestic Radio Law, there are frequency bands that cannot be transmitted and received at the same time. For example, the 920 MHz band is an example. When performing distance measurement in such a frequency band, transmission and reception must be performed in chronological order. In the present embodiment, an example corresponding to such a case of time-series transmission / reception is shown.
(Issues in time-series transmission and reception)
If it is specified that only one wave can be transmitted and received between the devices 1 and 2 at the same time, it is necessary to transmit and receive at least four waves necessary for distance measurement in chronological order. However, when time-series transmission / reception is performed, the phase for the delay generated in the time-series processing is added to the detection phase, and the phase required for propagation cannot be obtained. The reason for this will be described by modifying the above equation (58).

The broken line portion in FIG. 6 is executed almost at the same time, but when one wave is transmitted / received by time series processing, the broken line portion is as shown in FIG. 11A.

Similarly to the above, in the devices 1 and 2 separated from each other by the distance R, the phase (shift amount) when the signal of _{the angular frequency ω C1} + ω _{B1 transmitted from the device 1 is detected in the device 2 is set to θ H1} , and the device 1 is set. The phase when the signal of the angular frequency ω _{C1- ω B1} transmitted from the device 2 is detected by the device 2 is θ _{L1, and the phase when the signal of the angular frequency ω C2} + ω _B2 transmitted from the device 2 is detected by the device 1 ( The shift amount) is set to θ _{H2, and the phase when the signal of the angular frequency ω C2- ω B2} transmitted from the device 2 is detected by the device 1 is set to θ _L2 .

Now, for example, the phase detection order is θ _H1 , θ _L2 , θ _H2 , and θ _L1 . Further, as shown in FIGS. 11B and 11C, it is assumed that each transmission signal is transmitted and received with a time lag of T. In this case, the following equation (79), which is a modification of the above equation (58), is established by substituting time into (t) of the above equations (27), (37), (47) and (57). do.
{Θ _H1 (t) -θ _L1 (t + 3T)} + {θ _H2 (t + 2T) -θ _L2 (t + T)}
= (Θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) + (ω _{C1- ω C2} ) 4T… (79)
The final term of the above equation (79) is the phase added by time series transmission / reception. This added phase is the result of multiplying the local angular frequency substantially the same as the angular frequency of the received RF (high frequency) signal by the error angular frequency of the devices 1 and 2 and the delay 4T. When the local frequency is 920 [MHz], the frequency error is 40 [ppm], and the delay T is 0.1 [ms], the added phase is 360 ° × 14.7, and the error due to the added phase is It turns out that it is too large to measure the distance correctly.

Next, it is assumed that the phase detection order is θ _H1 , θ _L1 , θ _H2 , and θ _L2. 12A and 12B show an example in this case. In this case, the following equation (58) is modified to obtain the following equation (80).
{Θ _H1 (t) -θ _L1 (t + T)} + {θ _H2 (t + 2T) -θ _L2 (t + 3T)}
= (Θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) + (ω _{B1- ω B2} ) 4T… (80)
The final term of Eq. (80) is the phase added by time series transmission / reception. This added phase is the result of multiplying the error angular frequency of the devices 1 and 2 by the delay 4T with respect to the baseband local angular frequency which is substantially the same as the low angular frequency of the received high frequency signal. When the baseband local frequency is 5 [MHz], the frequency error is 40 [ppm], and the delay T is 0.1 [ms], 360 ° x 0.08 = 28.8 °, which is more accurate than the previous example. You can see that it can be distanced.

However, even in this case, whether or not the error amount is within the permissible error of the system specification depends on the system. This embodiment presents a time-series procedure for reducing the distance error generated by time-series transmission / reception. In this embodiment, the procedure in consideration of the transmission / reception regulation specified by the Radio Law is shown.
(Example of specific procedure (8 times alternation sequence))
First, consider the effect of transmission delay.

The following equation (81) is obtained by modifying the above equation (58).
{Θ _H1 (t) + θ _H2 (t)}-{θ _L1 (t) + θ _L2 (t)} = (θ _τH1 + θ _τH2 )-(θ _τL1 + θ _τL2 )… (81)
In addition, here
θ _H1 (t) + θ _H2 (t) = θ _τH1 + θ _τH2 … (82)
θ _L1 (t) + θ _L2 (t) = θ _τL1 + θ _τL2 … (83)
Is.

In wireless communication, there is a provision that when a signal addressed to you is received, you can reply without a carrier sense. According to this, immediately after the transmission of the signal from the device 1 to the device 2 is completed, the signal is returned from the device 2 to the device 1. To simplify the analysis, it is assumed that the device 2 returns to the device 1 after _{t 0 after the device 1 transmits.} The following equation (84) can be obtained from the equations (27) and (37).
θ _H1 (t) + θ _H2 (t + t ₀ ) = θ _τH1 + θ _τH2 + {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (84)
The delay t ₀ is the shortest time in the time series, and includes the time for _{transmitting the signal of the angular frequency ω C1} + ω _B1 from the device 1 to the device 2, the transmission / reception timing margin, and the propagation delay. The right side, the third term, and the fourth term are phase errors due to the _{delay t 0.} The fourth term is particularly problematic due to the high frequency, which will be mentioned later.

Next, it is assumed that a delay T is further added to the left side of the equation (84). FIG. 13 shows such a transmission procedure. As shown in FIG. 13, the added value of the detected phase in this case is the same regardless of the addition of the delay T. Therefore, the following equation (85) is obtained.
θ _H1 (t + T) + θ _H2 (t + t ₀ + T) = θ _τH1 + θ _τH2 + {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (85)
The right side of the above equation (85) and the right side of the above equation (84) are the same. That is, if the relative time difference is the same (T in the above example), the addition result of the phase of the signal transmitted from the device 1 received by the device 2 and the phase of the signal transmitted from the device 2 received by the device 1 is , It does not change regardless of the delay T. That is, the addition result of these phases becomes a value that does not depend on the delay T.

Next, the same applies to the transmission / reception of the angular frequency ω _{C1- ω B1 signal between the devices 1 and 2.} That is, the following equations (86) and (87) can be obtained from the above equations (47) and (57).
θ _L1 (t) + θ _L2 (t + t ₀ ) = θ _τL1 + θ _τL2 + {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (86)
θ _L1 (t + T) + θ _L2 (t + t ₀ + T) = θ _τL1 + θ _τL2 + {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (87)
From the above discussion, after the bidirectional transmission and reception of the angular frequency omega _C1 + omega _B1 signals, consider a sequence of transmitting and receiving the angular frequency omega _C1 - [omega] _B1 signal. Based on the transmission start time from the device 1 the angular frequency omega _C1 + omega _B1 signal and a transmission start time of the angular frequency omega _C1 - [omega] _B1 signal from the device 1 is T, the following from (84) and (87) below Equation (88) is obtained. However, T> t ₀ .
θ _H1 (t) + θ _H2 (t + t ₀ )-{θ _L1 (t + T) + θ _L2 (t + t ₀ + T)}
= Θ _τH1 −θ _τL1 + θ _τH2 −θ _τL2 +2 (ω _{B1- ω B2} ) t ₀ … (88)
The final term on the left side of the above equation (88) is the phase error due to the transmission delay. Delay error of a local frequency for the received high frequency is canceled by taking the difference between the angular frequency omega _{C1 +} omega _B1 signal and the angular frequency omega _C1 - [omega] _B1 signal. Therefore, the phase error is the product of the shortest delay time t _{0 in} time series and the error of the local angular frequency for the baseband (for example, 2π × 5 [MHz]). If the delay time t ₀ is set small, the error becomes small. Therefore, depending on the value of the delay time t ₀ , it can be said that distance measurement without any problem in accuracy is possible in actual use.

Next, a method of removing the final term of the above equation (88), which is a factor of the distance estimation error, will be described.

From the above equations (27) and (37), the following equation (89) can be obtained.
θ _H1 (t + t ₀ ) + θ _H2 (t) = θ _τH1 + θ _τH2 − {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (89)
Even if a predetermined delay D is added to the left side of the equation (89), the value on the right side does not change as described above. Therefore, the following equation (90) is obtained.
θ _H1 (t + t ₀ + D) + θ _H2 (t + D) = θ _τH1 + θ _τH2 − {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (90)
By adding the above equations (84) and (90), the following equation (91) is obtained.
θ _H1 (t) + θ _H2 (t + t ₀ ) + θ _H1 (t + t ₀ + D) + θ _H2 (t + D) = 2 (θ _τH1 + θ _τH2 )… (91)
The left side of FIG. 14 shows the state of the above equation (91). _{When D = t 0} in this equation (91), the following equation (92) is obtained.
θ _H1 (t) + 2 θ _H2 (t + t ₀ ) + θ _H1 (t + 2t ₀ ) = 2 (θ _τH1 + θ _τH2 )… (92)
The right-hand side of the above equation (92) is only a term of radio wave propagation delay according to a distance that does not depend on time.

From the above equations (47) and (57), the following equation (93) can be obtained.
θ _L1 (t + t ₀ ) + θ _L2 (t) = θ _τL1 + θ _τL2 − {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (93)
Even if a predetermined delay D is added to the left side of the equation (93), the value on the right side does not change. Therefore, the following equation (94) can be obtained.
θ _L1 (t + t ₀ + D) + θ _L2 (t + D) = θ _τL1 + θ _τL2 − {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (94)
By adding the above equations (86) and (94), the following equation (95) is obtained.
θ _L1 (t) + θ _L2 (t + t ₀ ) + θ _L1 (t + t ₀ + D) + θ _L2 (t + D) = 2 (θ _τL1 + θ _τL2 )… (95)
In this equation (95), when D = t ₀ , the following equation (96) is obtained.
θ _L1 (t) + 2 θ _L2 (t + t ₀ ) + θ _L1 (t + 2t ₀ ) = 2 (θ _{τ L1} + θ _{τ L2} )… (96)
The right-hand side of the above equation (96) is only a term of radio wave propagation delay according to a distance that does not depend on time.

Above (92) and (96) below, the apparatus and phase detects the transmission signal 1 in the apparatus 2, and the phase detection in the transmission signal apparatus 1 of the device 2 after t _0, the transmission signal again device 1 after 2t ₀ Means a sequence in which the phase is detected by the device 2. Hereinafter, the transmission of the transmission signal of the device 1 and the phase detection of the device 2 with respect to the transmission signal of the device 1 and the phase detection of the device 1 with respect to the transmission of the transmission signal of the device 2 alternate with each other, and these phase detections are performed again with a time lag. The measurement will be called "repeated alternation".

That is, in the apparatus 1, which receives and transmits each of the two carrier signals, by performing the repeated alternating of transmitting and receiving a carrier signal from again device 1 or 2 in t ₀ interval to the other device, transmission The order and time of the above are limited, but accurate distance measurement is possible without being subject to time dependence.

Further, depending on the transmission / reception sequence of the carrier signal, accurate distance measurement that does not depend on time is possible even if _{repeated alternation is not performed at t 0 intervals.}

That is, even if the fixed delay T is added to the left side of the above equation (95), the right side is constant.
θ _L1 (t + T) + θ _L2 (t + t ₀ + T) + θ _L1 (t + t ₀ + D + T) + θ _L2 (t + D + T) = 2 (θ _τL1 + θ _τL2 )… (97)
From the above equations (91) and (97), the following equation (98) can be obtained.
θ _H1 (t) + θ _H2 (t + t ₀ ) + θ _H1 (t + t ₀ + D) + θ _H2 (t + D)
-{Θ _L1 (t + T) + θ _L2 (t + t ₀ + T) + θ _L1 (t + t ₀ + D + T) + θ _L2 (t + D + T)}
= 2 {(θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 )} = 4 × (ω _B1 + ω _B2 ) τ ₁ … (98)
The (98) equation, after repeated alternating angular frequency omega _C1 + omega _B1, the round trip omega _C2 + omega _B2 at time intervals D, round-trip from the measurement start angular frequency omega _C1 - [omega] _B1 after T, ω _C2 -ω _B2 Is shown in a sequence in which Shown.

14 and 15 show this sequence. By measuring the phase in such a sequence, only the propagation delay component can be extracted. That is, the control unit 11 of the device 1 _{transmits a transmission wave having an angular frequency of ω C1} + ω _B1 (hereinafter referred to as a transmission wave H1A) at a predetermined timing. Immediately after receiving the transmission wave H1A, the control unit 21 of the device 2 transmits a transmission wave having an angular frequency of ω _C2 + ω _B2 (hereinafter referred to as transmission wave H2A). Further, the control unit 21 of the device 2 transmits the transmission wave having an angular frequency of ω _C2 + ω _B2 (hereinafter referred to as the transmission wave H2B) again after the transmission wave H2A is transmitted. After receiving the second transmission wave H2B, the control unit 11 of the device 1 transmits the transmission wave having an angular frequency of ω _C1 + ω _B1 (hereinafter, referred to as the transmission wave H1B) again.

Further, the control unit 11 further _{transmits a transmitted wave having an angular frequency of ω C1- ω B1} (hereinafter referred to as a transmitted wave L1A). Immediately after receiving the transmission wave L1A, the control unit 21 of the device 2 transmits a transmission wave having an angular frequency of ω _{C2- ω B2} (hereinafter referred to as transmission wave L2A). Further, the control unit 21 of the device 2 transmits the transmission wave having an angular frequency of ω _{C2- ω B2} (hereinafter referred to as the transmission wave L2B) again after the transmission wave L2A is transmitted. After receiving the second transmission wave L2B, the control unit 11 of the device 1 transmits the transmission wave having an angular frequency of ω _{C1- ω B1} (hereinafter referred to as the transmission wave L1B) again.

_{In this way, as shown in FIGS. 14 and 15, the control unit 21 of the apparatus 2 acquires the phase θ H1} (t) based on the transmitted wave H1A from the predetermined reference time 0 to the predetermined time, and determines the phase θ H1 (t) from the time t ₀ + D. _{The phase θ H1} (t + t ₀ + D) based on the transmitted wave H1B is acquired in time, the phase θ _L1 (t + T) based on the transmitted wave L1A is acquired from the time T at a predetermined time, and the transmitted wave is transmitted from the _{time t 0 + D + T at a predetermined time.} The phase θ _L1 (t + t ₀ + D + T) based on L1B is acquired.

Further, the control unit 11 of the device 1 _{acquires the phase θ H2} (t + t ₀ ) based on the transmitted wave H2A from _{the time t 0 at a predetermined time, and the phase θ H2} (t + D) based on the transmitted wave H2B from the time D to the predetermined time. _{Is acquired, the phase θ L2} (t + t ₀ + T) based on the transmitted wave L2A is acquired from the time t ₀ + T at a predetermined time, _{and the phase θ L2} (t + D + T) based on the transmitted wave L2B is acquired from the time D + T at a predetermined time.

At least one of the devices 1 or 2 transmits the phase information, that is, the calculation result of the above-mentioned equation (98) of the obtained four phases or two phase differences or phase differences to the other. The control unit of the device 1 or 2 that has received the phase information calculates the distance by the calculation of the above equation (98). In addition, although it was described as the phase difference calculation in steps S7 and S17 of FIG. 6, in this case, it is not always necessary to calculate the phase difference in steps S7 and S17, and the phase difference may be calculated when calculating the distance in S19. ..

As described above, in the examples of FIGS. 14 and 15, by repeatedly alternating the carrier signals from the first device and the second device, accurate distance measurement is possible even when the carrier signals cannot be transmitted and received at the same time. For example, the first device and the second device each transmit signals of two angular frequencies to the second device and the first device in a predetermined sequence twice, respectively, and cause a phase difference in each of the first device and the second device. Ask. Then, the device that transmits the obtained phase information from one of the first device and the second device to the other and receives the phase information is based on the eight phases obtained by the first device and the second device. Calculate the distance between the first device and the second device. As a result, the distance between the first device and the second device is accurately calculated regardless of the initial phase of the oscillators of the first device and the second device. In this way, accurate distance measurement is possible by removing the error of distance estimation even when signals of each angular frequency are transmitted and received at timings deviated from each other without being transmitted at the same time.

In the examples of FIGS. 14 and 15, the directions of transmission and reception of the carrier signal are alternated between the device 1 and the device 2, and the transmission and reception are performed four times, and the devices 1 and 2 transmit and transmit a total of eight times. Although phase detection is performed, the transmission / reception sequence of FIGS. 14 and 15 is hereinafter referred to as an eight-time alternating sequence.
<Transmission sequence to reduce communication time>
As described above, in the communication type distance measurement technology adopted in the present embodiment, by adopting the eight-time alternation sequence, the influence of the time lag can be completely eliminated and accurate distance measurement can be performed. .. However, in the 8-time alternation sequence, the devices 1 and 2 need to transmit two waves twice, that is, the device 1 needs to transmit four times and the device 2 also needs to transmit four times, and the time required for distance measurement is relatively long. ..
(4 police box sequence)
Therefore, in the present embodiment, we propose a method (four-time alternation sequence) for measuring the distance in a shorter time while enabling accurate distance measurement.

16 and 17 are explanatory views showing a transmission sequence for shortening the communication time in the present embodiment. Further, FIG. 18 is a timing chart corresponding to the sequence of FIG.

As shown in FIG. 16, in this transmission sequence, the device 1 transmits the transmission wave ω _C1 + ω _B1 , the device 2 transmits the transmission wave ω _C2 + ω _B2 , and the device 1 generates _{ω C1- ω B1.} And the device 2 _{generates ω C2- ω B2} and transmits it. As described above, the transmission sequence of FIGS. 16 and 17 is referred to as a four-time alternating sequence because the transmission is performed by alternating four times.

Next, even when the 4-fold alternation sequence is adopted, a method of performing accurate distance measurement by completely eliminating the influence of the time lag will be described as in the 8-fold alternation sequence.

The above equations (84) to (87) obtained in consideration of time series transmission can be transformed into the following equations (112) to (115), respectively. That, (84) _{t 0} a by replacing 2t ₀ (112) type is obtained. Further, by replacing T in Eq. (85) with t ₀ , Eq. (113) can be obtained. Further, as described above, even if the relatively same delay is applied, the calculated phase addition result does not change. Therefore, a predetermined delay T is added to the left side of the equation (86), and t _{0 is changed} to 2t ₀ . By substituting, equation (114) is obtained. Similarly, by replacing T in Eq. (87) with T + t ₀ , Eq. (115) can be obtained.
θ _H1 (t) + θ _H2 (t + 2t ₀ ) = θ _τH1 + θ _τH2 + 2 {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (112)
θ _H1 (t + t ₀ ) + θ _H2 (t + 2t ₀ ) = θ _τH1 + θ _τH2 + {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (113)
θ _L1 (t + T) + θ _L2 (t + 2t ₀ + T) = θ _τL1 + θ _τL2 + 2 {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (114)
θ _L1 (t + t ₀ + T) + θ _L2 (t + 2t ₀ + T) = θ _τL1 + θ _τL2 + {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (115)
Next, when the 2 × (113) equation − (112) equation − {2 × (115) equation − (114) equation} is obtained, the following equation (116) is obtained.
θ _H2 (t + 2t ₀ ) + 2θ _H1 (t + t ₀ ) -θ _H1 (t)-{θ _L2 (t + 2t ₀ + T) + 2θ _L1 (t + t ₀ + T) -θ _L1 (t + T)}
= (Θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) = 2 × (ω _B1 + ω _B2 ) τ ₁ … (116)
_{This equation (116) shows that the delay time τ 1} can be obtained by adding the phase differences obtained in the devices 1 and 2. That is, Eq. (116) shows that accurate distance measurement is possible by removing the distance estimation error factor, as in Eq. (98) showing the above-mentioned eight-time alternation sequence.

Further, the equation (116) indicates that the phase measurement is performed a total of 6 times. That is, the detection phase theta _H1 of device 2 Time t = 0 (t), the device detection phase θ _{H1 (t +} t 0) of time t = _{t 0} 2, the time device 1 t = 2t ₀ detected phase theta _H2 ( t + _2t 0), the time device 2 t = T of the detected phase θ _L1 (t + T), the time device 2 _{t =} t 0 + T of the detected phase _{θ L1 (t + t 0 +} T), the device 1 of the time t = _2t 0 + T It shows that the detection phase θ _L2 (t + 2t ₀ + T) may be sequentially performed.

In this case, the _{phases of θ H1} (t) and θ _H1 (t + t ₀ ) can be measured by one transmission sequence, and θ _L1 (t + T) and θ _L1 (t + t ₀ + T) are 1 The phase can be measured by the transmission sequence of times.

FIG. 17 shows this sequence. When realizing the sequence of FIG. 17, the broken line portion of FIG. 6 is shown in FIG. 18, for example. In order to realize the sequence of FIG. 17, the control unit 11 of the device 1 transmits a transmitted wave having an angular frequency of ω _C1 + ω _{B1 to the device 2 at a timing corresponding to t = 0 and t = t 0.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _C2 + ω _{B2 at a timing corresponding to t = 2t 0} immediately after receiving the transmitted wave.

Furthermore, the control unit 11 of the device 1 is the angular frequency at a timing corresponding to t = T and _{t =} t 0 + T transmits a transmission wave ω _C1 -ω _B1. Control unit 21 of the apparatus 2, at a timing corresponding to the immediately following reception of the transmitted wave t = _2t 0 + T, is the angular frequency to transmit the transmission wave ω _C2 -ω _B2.

In this way, as shown in FIG. 17, the control unit 21 of the device 2 _{acquires the phases θ H1} (t) and θ _H1 (t + t ₀ ) based on the received signals at _{the times t = 0 and t = t 0,} and obtains the time. _{The phases θ L1} (t + T) and θ _L1 (t + t ₀ + T) are acquired based on the received signals at t = T and t = t _{0 + T.}

The control unit 11 of the apparatus 1, the time t = based on the received signal at 2t ₀ acquires the phase _{θ H2 (t + 2t 0)} , the phase theta _L2 based on the received signal in the time _{t = 2t 0 + T (t} + 2t 0 + T) is acquired.

One of the devices 1 and 2 whose phase is measured in the four-time alternating sequence transmits the phase information acquired by the own device to the other of the devices 1 and 2. Of the devices 1 and 2, the device for which the phase information is provided calculates the distance by the calculation of the above equation (116). In this way, even when the four-time alternation sequence is adopted, it is possible to extract only the propagation delay component and perform accurate distance measurement.

19 and 20 are explanatory views for explaining the effect of the embodiment. 19 and 20 show the transmission sequence from the device 1 and the device 2 required for one distance measurement, taking time in the horizontal direction. FIG. 19 shows a sequence corresponding to the 8-fold alternation sequence of FIG. 15, and FIG. 20 shows a sequence corresponding to the 4-fold alternation sequence of FIG.

Note that FIGS. 19 and 20 take into consideration that there is a frequency band (sub-GHz in Japan (920 MHz band)) for which simultaneous transmission / reception is prohibited by the Radio Law. In FIGS. 19 and 20, the two transmitted waves output from the device 1 are referred to as transmission waves A1 and B1, and the two transmitted waves output from the device 2 are referred to as transmission waves A2 and B2. The examples of FIGS. 19 and 20 show an example in which transmission waves A1 and A2 are transmitted and received by channel CH61 in the 928MHz band, and transmission waves B1 and B2 are transmitted and received by channel CH33 in the 922.4MHz band.

In FIG. 19, which shows an eight-time alternation sequence, the apparatus 1 transmits the transmission wave A1 after performing carrier sense for, for example, 128 μS (seconds). After receiving the transmission wave A1, the device 2 performs carrier sense for, for example, 128 μS, and then transmits the transmission wave A2. Further, the device 2 transmits the transmission wave A2 again following the transmission of the transmission wave A2. After receiving the transmission wave A2 from the device 2, the device 1 performs carrier sense for, for example, 128 μS (seconds), and then transmits the transmission wave A1.

Next, the device 1 performs carrier sense for, for example, 128 μS (seconds) following the transmission of the transmission wave A1, and then transmits the transmission wave B1. After receiving the transmission wave B1, the device 2 performs carrier sense for, for example, 128 μS, and then transmits the transmission wave B2. Further, the device 2 transmits the transmission wave B2 again following the transmission of the transmission wave B2. After receiving the transmission wave B2 from the device 2, the device 1 performs carrier sense for, for example, 128 μS (seconds), and then transmits the transmission wave B1.

On the other hand, in FIG. 20, which shows a four-time alternation sequence, the apparatus 1 transmits the transmission wave A1 after performing carrier sense for, for example, 128 μS (seconds). The device 1 may transmit the transmission wave A1 so that the device 2 can receive the transmission wave A1 twice at the timings of time t = 0 and t = t _0. After receiving the transmission wave A1 twice, the device 2 performs carrier sense for, for example, 128 μS, and transmits the transmission wave A2.

Next, after receiving the transmission wave A2 from the device 2, the device 1 performs carrier sense for, for example, 128 μS (seconds), and transmits the transmission wave B1. The device 1 may transmit the transmission wave B1 so that the device 2 can receive the transmission wave B1 twice at the timing of time t = T and t = t _{0 + T.} After receiving the transmission wave B1 twice, the device 2 performs carrier sense for, for example, 128 μS, and transmits the transmission wave B2.

As is clear from the comparison between FIGS. 19 and 20, the time required for communication in the 4-fold alternation sequence is 6/8 times that of the 8-fold alternation sequence, and the communication time can be shortened. At the time of carrying out the carrier sense, the number of carrier senses in the 4-fold alternation sequence is 4/6 times the number of carrier senses in the 8-fold alternation sequence.

By the way, the above equation (98) showing the eight-fold alternating sequence is established when the calculation result of the detection phase is obtained in the remainder system of 2π, that is, between 0 and 2π. Assuming that the left side of equation (98) is S _8A and a certain integer is n _8A , the following equation (99) is established.

S _8A + n _8A x 2π = 4 (ω _B1 + ω _B2 ) τ ₁ ... (99)
By modifying this equation (99), the following equation (100) can be obtained.

(Ω _B1 + ω _B2 ) τ ₁ = (S _8A / 4) + (n _8A × π / 2)… (100)
The above equation (100) shows that (ω _B1 + ω _B2 ) τ ₁ has an uncertainty of π / 2 period. That is, (ω _B1 + ω _B2 ) τ ₁ is obtained by the remainder system of π / 2.

Therefore, since τ ₁ = (R / c), the maximum distance that can be measured in the 8-time alternation sequence (hereinafter referred to as the maximum distance measurement distance) is the distance according to the above equation (61) by transmitting four waves at the same time. Is 1/2 of the case of obtaining.

On the other hand, the above equation (116) showing the four-fold alternating sequence also holds when the calculation result of the detection phase is obtained in the remainder system of 2π, that is, between 0 and 2π. Assuming that the left side of equation (116) is S _4A and a certain integer is n _4A , the following equation (117) is established.

(Ω _B1 + ω _B2 ) τ ₁ = (S _4A / 2) + (n _4A × π)… (117)
The above equation (117) shows that (ω _B1 + ω _B2 ) τ ₁ has a pion-period uncertainty. That is, (ω _B1 + ω _B2 ) τ ₁ is obtained by the remainder system of π.

From the above, the maximum distance that can be measured in the 4-fold alternation sequence (hereinafter referred to as the maximum distance-measuring distance) is twice the maximum distance-measuring distance in the 8-fold alternation sequence. It can be seen that the same maximum distance measurement distance as is obtained.

The result of measuring a distance greater than or equal to the maximum distance measurement distance is the same as the result of measuring a short distance, and the distance cannot be distinguished. It is advantageous. In addition, the maximum distance measurement distance _{increases as (ω B1} + ω _B2 ) decreases, but even if this value is doubled in the 4-time alternation sequence, the same maximum distance measurement distance as in the 8-fold alternation sequence can be obtained. .. In other words, the 4-fold alternation sequence can increase the combinations of usable frequencies (channels) if the same maximum ranging distance as the 8-fold alternation sequence can be obtained, and it is easy to measure with an empty channel. There is an advantage of becoming.

As described above, in the present embodiment, accurate distance measurement is possible by repeatedly alternating the carrier signals from the first device and the second device. In this case, by adopting the 4-fold alternation sequence, it is possible to shorten the communication time required for distance measurement as compared with the 8-fold alternation sequence. Moreover, the 4-fold alternation sequence can double the maximum distance measurement distance as compared with the 8-fold alternation sequence, and can increase the degree of freedom of the frequency used.
(Second Embodiment)
FIG. 21 is an explanatory diagram for explaining a second embodiment of the present invention. FIG. 21 shows a transmission sequence for shortening the communication time. Further, FIG. 22 is a timing chart corresponding to the sequence of FIG. 21. The hardware configuration in this embodiment is the same as that in the first embodiment. The present embodiment is different from the first embodiment only in that a four-time alternating sequence having a different transmission order from the four-time alternating sequence in the first embodiment is adopted.

Also in the transmission sequence of the present embodiment, as shown in FIG. 16, the device 1 two transmission waves omega _C1 + omega _B1, and generates and transmits a omega _C1 - [omega] _B1, device 2 two transmission waves omega _C2 + Ω _B2 and ω _C2 −ω _B2 are generated and transmitted.

In the four-time alternating sequence of the first embodiment, the transmission time of the device 1 is about twice the transmission time of the device 2. Similarly, it is possible to measure the distance by setting the transmission time of the device 2 to about twice the transmission time of the device 1. This embodiment shows an example in this case.

The above equations (84) to (87) obtained in consideration of time series transmission can be transformed into the following equations (118) to (121), respectively. That is, the equation (118) is the same equation as the equation (84). Equation (119) can be obtained by replacing T in equation (85) with T = 0 and _{replacing t 0} with 2t _0. Further, the equation (120) can be obtained by adding a predetermined delay T to the left side of the equation (86). Similarly, (87) _{t 0} a by replacing 2t ₀ (121) type is obtained.
θ _H1 (t) + θ _H2 (t + t ₀ ) = θ _τH1 + θ _τH2 + {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (118)
θ _H1 (t) + θ _H2 (t + 2t ₀ ) = θ _τH1 + θ _τH2 + 2 {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (119)
θ _L1 (t + T) + θ _L2 (t + t ₀ + T) = θ _τL1 + θ _τL2 + {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (120)
θ _L1 (t + T) + θ _L2 (t + 2t ₀ + T) = θ _τL1 + θ _τL2 + 2 {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (121)
Next, when the 2 × (118) equation- (119) equation-{2 × (120) equation- (121) equation} is obtained, the following equation (122) is obtained.
θ _H1 (t) + 2 θ _H2 (t + t ₀ ) -θ _H2 (t + 2t ₀ )-{θ _L1 (t + T) + 2θ _L2 (t + t ₀ + T) -θ _L2 (t + 2t ₀ + T)}
= (Θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) = 2 × (ω _B1 + ω _B2 ) τ ₁ … (122)
_{Τ 1} can be obtained from this equation (122). That is, Eq. (122) shows that accurate distance measurement is possible by removing the distance estimation error factor, as in the case of the four-time alternation sequence of the first embodiment.

Further, the equation (122) indicates that the phase measurement is performed a total of 6 times. That is, the detection phase theta _H1 of device 2 Time t = 0 (t), detected phase theta _H2 of time device _{1 t = t 0 (t +} t 0), detected phase theta _H2 of time device 1 t = 2t ₀ ( t + _2t 0), the time device 2 t = T of the detected phase θ _L1 (t + T), the time device 1 _{t =} t 0 + T of the detected phase _{θ L2 (t + t 0 +} T), the device 1 of the time t = _2t 0 + T It shows that the detection phase θ _L2 (t + 2t ₀ + T) may be sequentially performed.

In this case, the _{phases of θ H2} (t + t ₀ ) and θ _H2 (t + 2t ₀ ) can be measured by one transmission sequence, and θ _L2 (t + t ₀ + T) and θ _L2 (t + 2t ₀ + T). Can measure the phase with a single transmission sequence.

FIG. 21 shows this sequence. When realizing the sequence of FIG. 21, the broken line portion of FIG. 6 is shown in FIG. 22, for example. In order to realize the sequence of FIG. 21, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1} + ω _{B1 to the device 2 at a timing corresponding to t = 0.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _C2 + ω _{B2 at a timing corresponding to t = t 0} and t = 2t ₀ immediately after receiving the transmitted wave.

Further, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1- ω B1 at a timing corresponding to t = T.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _{C2- ω B2 at a timing corresponding to t = t 0} + T and t = 2t ₀ + T immediately after receiving the transmitted wave.

Thus, as shown in FIG. 21, the control unit 21 of the device 2 _{acquires the phase θ H1 (t) based on the received signal at time t = 0, and the phase θ L1} based on the received signal at time t = T. Get (t + T).

The control unit 11 of the apparatus 1 acquires the phase θ _{H2 (t} + t ₀₎ and θ _H2 (t + 2t ₀₎ on the basis of the received signal in the time t = _{t 0} and t = 2t _0, time _{t =} t 0 + T _{And the phases θ L2} (t + t ₀ + T) and θ _L2 (t + 2t ₀ + T) are acquired based on the received signal at t = 2t _{0 + T.}

One of the devices 1 and 2 whose phase is measured by the four-time alternating sequence shown in FIG. 21 transmits the phase information acquired by the own device to the other of the devices 1 and 2. Of the devices 1 and 2, the device for which the phase information is provided calculates the distance by the calculation of the above equation (122). In this way, even when the four-fold alternating sequence shown in FIG. 21 is adopted, it is possible to extract only the propagation delay component and perform accurate distance measurement.

The communication sequence in the case of performing distance measurement by adopting this embodiment corresponds to the one in which the length of the A1 period and the length of the A2 period in FIG. 20 are exchanged, and the length of the B1 period and the length of the B2 period are exchanged. do. Therefore, also in this embodiment, the communication time required for distance measurement can be shortened.

Further, also in the four-time alternation sequence in the present embodiment, the maximum distance measurement distance is twice the maximum distance measurement distance in the eight-time alternation sequence, which is the same maximum distance measurement as when the distance is calculated by the above equation (61). It is clear that the distance can be obtained.

As described above, in the present embodiment, the same effect as that of the first embodiment can be obtained.

In general, in a wireless transmitter / receiver, the power consumption at the time of transmission is larger than the power consumption at the time of reception. Therefore, in the first embodiment, the device 1 consumes more power required for communication for distance measurement than the device 2, and in the second embodiment, the device 2 consumes more power than the device 1. The power consumption required for communication for distance measurement is large. Therefore, it is sufficient to decide which of the first and second embodiments is adopted depending on which of the two devices 1 and 2 is the device whose power consumption is desired to be reduced. For example, in the case where the device 1 is a fixed device and the device 2 is a portable device driven by a battery, it is better to adopt the first embodiment in which the power consumption of the device 2 is small.
(Third Embodiment)
23 and 24 are explanatory views for explaining the third embodiment of the present invention. 23 and 24 show a transmission sequence for shortening the communication time. The hardware configuration in this embodiment is the same as that in the first embodiment. The present embodiment is different from the first and second embodiments only in that it employs a four-time alternating sequence in which the transmission order is different from the four-time alternating sequence in the first and second embodiments. ..

Also in the transmission sequence of the present embodiment, as shown in FIG. 16, the device 1 two transmission waves omega _C1 + omega _B1, and generates and transmits a omega _C1 - [omega] _B1, device 2 two transmission waves omega _C2 + Ω _B2 and ω _C2 −ω _B2 are generated and transmitted.

The values of the 2 × (113) − (112) equations obtained to obtain the (116) equation of the first embodiment and the 2 obtained to obtain the (122) equation of the second embodiment. The values of the formulas × (118) and − (119) are all the same value (θ _τH1 + θ _τH2 ).

Similarly, in order to obtain the values of the 2 × (115) − (114) equations obtained to obtain the (116) equation of the first embodiment and the (122) equation of the second embodiment. The obtained values of the formulas 2 × (120) − (121) are all the same value (θ _τL1 + θ _τL2 ).

Therefore, {2 × (113) equation − (112) equation} and {2 × (118) equation − (119) equation} are exchanged, and (118) equation, (119) equation, (114) equation and (115) equation are exchanged. The same results as those of the equations (116) and (122) can be obtained by using the following equation (116a) obtained by using the equation (116).
θ _H1 (t) + 2 θ _H2 (t + t ₀ ) -θ _H2 (t + 2t ₀ )-{θ _L2 (t + 2t ₀ + T) + 2θ _L1 (t + t ₀ + T) -θ _L1 (t + T)}
= (Θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) = 2 × (ω _B1 + ω _B2 ) τ ₁ … (116a)
Similarly, the {2 × (115) equation- (114) equation} and the {2 × (120) equation − (121) equation} are exchanged, and the (112) equation, the (113) equation, and the (120) equation are replaced. And the following equation (116b) obtained by using the equation (121) can also be used to obtain the same result as the equations (116) and (122).
θ _H2 (t + 2t ₀ ) + 2θ _H1 (t + t ₀ ) -θ _H1 (t)-{θ _L1 (t + T) + 2θ _L2 (t + t ₀ + T) -θ _L2 (t + 2t ₀ + T)}
= (Θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) = 2 × (ω _B1 + ω _B2 ) τ ₁ … (116b)
FIG. 23 shows a four-time alternation sequence when the equation (116b) is used. Further, FIG. 24 shows a four-time alternation sequence when the equation (116a) is used.

In the example of FIG. 23, the control unit 11 of the device 1 transmits the transmitted wave having an angular frequency of ω _C1 + ω _{B1 to the device 2 at the timing corresponding to t = 0 and t = t 0.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _C2 + ω _{B2 at a timing corresponding to t = 2t 0} immediately after receiving the transmitted wave.

Further, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1- ω B1 at a timing corresponding to t = T.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _{C2- ω B2 at a timing corresponding to t = t 0} + T and t = 2t ₀ + T immediately after receiving the transmitted wave.

In this way, as shown in FIG. 23, the control unit 21 of the device 2 _{acquires the phases θ H1} (t) and θ _H1 (t + t ₀ ) based on the received signals at _{the times t = 0 and t = t 0,} and obtains the time. _{The phase θ L1} (t + T) is acquired based on the received signal at t = T.

Further, the control unit 11 of the device 1 _{acquires the phase θ H2} (t + 2t _{0 ) based on the received signal at time t = 2t 0, and} is based on the received signal at time t = t ₀ + T and t = 2t ₀ + T. Acquire the phases θ _L2 (t + t ₀ + T) and θ _L2 (t + 2t ₀ + T).

The distance can be calculated by using the equation (116b) based on these phases obtained in the devices 1 and 2.

Further, in the example of FIG. 24, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1} + ω _{B1 to the device 2 at a timing corresponding to t = 0.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _C2 + ω _{B2 at a timing corresponding to t = t 0} and t = 2t ₀ immediately after receiving the transmitted wave.

Furthermore, the control unit 11 of the device 1 is the angular frequency at a timing corresponding to t = T and _{t =} t 0 + T transmits a transmission wave ω _C1 -ω _B1. Control unit 21 of the apparatus 2, at a timing corresponding to the immediately following reception of the transmitted wave t = _2t 0 + T, is the angular frequency to transmit the transmission wave ω _C2 -ω _B2.

In this way, as shown in FIG. 24, the control unit 21 of the device 2 _{acquires the phase θ H1} (t) based on the received signal at time t = 0, and the received signal at time t = T and t = t ₀ + T. The phases θ _L1 (t + T) and θ _L1 (t + t ₀ + T) are acquired based on.

Further, the control unit 11 of the device 1 _{acquires the phases θ H2} (t + t ₀ ) and θ _H2 (t + 2t ₀ ) based on the received signals at _{the time t = t 0} and t = 2t ₀ , and the time t = 2t ₀ + T. _{The phase θ L2} (t + 2t ₀ + T) is acquired based on the received signal in.

The distance can be calculated by using the equation (116a) based on these phases obtained in the devices 1 and 2.

Other configurations and operations are similar to those of the first and second embodiments.

As described above, in the present embodiment as well, the same effects as those in the first and second embodiments can be obtained.
(Fourth Embodiment) (6 times alternating sequence)
25 and 26 are explanatory views for explaining a fourth embodiment of the present invention. 25 and 26 show a transmission sequence for reducing the communication time. The hardware configuration in this embodiment is the same as that in the first embodiment. The present embodiment is different from the first to third embodiments in that a six-time police box sequence capable of measuring a distance in substantially the same communication time as the four-time police box sequence is adopted.

As shown in FIG. 25, in this transmission sequence, the device 1 _{generates and transmits the transmission wave ω C1} + ω _B1 , the device 2 generates and transmits the transmission wave ω _C2 + ω B2, and the device 1 generates and transmits the _{transmission wave ω C2 + ω B2.} Generate ω _C1 + ω _B1 and send it again. Next, the device 1 _{generates and transmits ω C1- ω B1} , the device 2 generates and transmits ω _{C2- ω B2} , and the device 1 generates and transmits the transmission wave ω _{C1- ω B1} again. As described above, the transmission sequence of FIGS. 25 and 26 is referred to as a 6-time alternating sequence because the transmission is performed by alternating 6 times.

In the equation (98) showing the transmission sequence of FIG. 15, the transmission from the device 2 to the device 1 is performed a total of four times, but _{the transmission wave at time t = t 0} and t = D is transmitted by the device 1. The signals are the same except that the phase measurement time is different. Similarly, the transmitted waves of time t = t ₀ + T and t = D + T from the device 2 are the same signal except that the phase measurement time in the device 1 is different. Therefore, in the present embodiment, the transmission time is shortened by transmitting these transmitted waves at once. That is, in the equation (98), if D = t ₀ , the following equation (98') is derived.
θ _H1 (t) + 2 θ _H2 (t + t ₀ ) + θ _H1 (t + 2t ₀ )
− {Θ _L1 (t + T) + 2θ _L2 (t + t ₀ + T) + θ _L1 (t + 2t ₀ + T)}
= 2 {(θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 )} = 4 × (ω _B1 + ω _B2 ) τ ₁ … (98')
_{This equation (98') has a delay time τ 1} , that is, by adding the phase difference obtained in the devices 1 and 2 even by the 6-fold alternation sequence and the same as the equation (98) showing the 8-fold alternation sequence described above. , It is shown that the distance between the devices 1 and 2 can be accurately measured.

FIG. 26 shows this sequence. In order to realize the sequence of FIG. 26, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1} + ω _{B1 to the device 2 at a timing corresponding to t = 0.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _C2 + ω _{B2 at a timing corresponding to t = t 0} immediately after receiving the transmitted wave. The control unit 11 of the device 1 retransmits the transmitted wave having an angular frequency of ω _C1 + ω _{B1 at the timing corresponding to t = 2t 0} immediately after receiving the transmitted wave.

Further, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1- ω B1 at a timing corresponding to t = T.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _{C2- ω B2 at a timing corresponding to t = t 0} + T immediately after receiving the transmitted wave. The control unit 11 of the device 1 retransmits the transmitted wave having an angular frequency of ω _C1 − _{ω B1 at the timing corresponding to t = 2t 0} + T immediately after receiving the transmitted wave.

In this way, as shown in FIG. 26, the control unit 21 of the device 2 _{acquires the phases θ H1} (t) and θ _H1 (t + 2t ₀ ) based on the received signals at _{the times t = 0 and t = 2t 0,} and obtains the time. _{The phases θ L1} (t + T) and θ _L1 (t + 2t ₀ + T) are acquired based on the received signals at t = T and t = 2t _{0 + T.}

The control unit 11 of the apparatus 1, the time t = acquires phase theta _H2 a _(t + t ₀₎ on the basis of the received signal at _{t 0,} the phase theta _L2 based on the received signal in the time _{t = t 0 + T (t} + t 0 + T) is acquired.

One of the devices 1 and 2 whose phase is measured in the 6-time alternation sequence transmits the phase information acquired by the own device to the other of the devices 1 and 2. Of the devices 1 and 2, the device for which the phase information is provided calculates the distance by the calculation of the above equation (98'). In this way, even when the 6-time alternation sequence is adopted, it is possible to extract only the propagation delay component and perform accurate distance measurement.

The communication time required for distance measurement in the 6-time alternation sequence is substantially the same as the communication time required for distance measurement in the 4-time alternation sequence.
(Double the maximum distance measurement distance)
By the way, in the equation (98') showing the 6-fold alternation sequence, the same equations as the above equations (99) and (100) are established, and the maximum detectable distance measurement distance is 1/2 of the 4-fold alternation sequence. It becomes. However, it is possible to extend the maximum ranging distance to the same distance as the four-time alternation sequence by modifying the equation. Hereinafter, this method will be described.

Calculate the difference between the above equation (84) showing the case where the transmitted wave is transmitted to the device 1 after receiving the transmitted wave from the device 1 in the device 2 and the above (90) used to eliminate the distance estimation error factor. Then, the following equation (101) is obtained.
θ _H1 (t) + θ _H2 (t + t ₀ ) -θ _H1 (t + t ₀ + D) -θ _H2 (t + D) = 2 {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (101)
Similarly, when the equations (86)-(94) are calculated, the following equation (102) is obtained.
θ _L1 (t) + θ _L2 (t + t ₀ ) -θ _L1 (t + t ₀ + D) -θ _L2 (t + D) = 2 {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (102) )
Since the right side is constant even if the fixed delay T is added to t on the left side of equation (102), equation (103) can be obtained.
θ _L1 (t + T) + θ _L2 (t + t ₀ + T) -θ _L1 (t + t ₀ + D + T) -θ _L2 (t + D + T)
= 2 {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (103)
By calculating Equation (101) -Equation (103), the following equation (104) is obtained.
θ _H1 (t) + θ _H2 (t + t ₀ ) -θ _H1 (t + t ₀ + D) -θ _H2 (t + D)
−θ _L1 (t + T) −θ _L2 (t + t ₀ + T) + θ _L1 (t + t ₀ + D + T) + θ _L2 (t + D + T) = 4 (ω _B1 −ω _B2 ) t ₀ … (104)
In this equation (104), when D = t ₀ , the following equation (110) is obtained.
θ _H1 (t) -θ _H1 (t + 2t ₀ ) -θ _L1 (t + T) + θ _L1 (t + 2t ₀ + T) = 4 (ω _{B1- ω B2} ) t ₀ ... (110)
The result of Eq. (110) can be obtained by the remainder system of 2π. If the left side of equation (110) is set to S _{4, the following} equation (105) can be obtained using the integer n _{4.
(Ω B1 -ω B2) t 0} = (S 4/4) + (n 4 π / 2) ... (105)
_{(Ω B1- ω B2} ) t _{0 in} Eq. (105) has an uncertainty of π / 2 period.

As the design values of the device, when the baseband local frequency is 5 [MHz], the maximum frequency error between transmission and reception is ± 40 [ppm], and the delay t ₀ is 0.1 [ms], 360 ° × (5 ×) ^{10 6 × ± 40 [ppm]} ) = a ± 7.2 °. That is, it is clear that the left side of the above equation (105) is within −π / 4 to π / 4 [rad] = 45 to 45 °, and it can be seen that uncertainty can be eliminated. Therefore, the following equation (111) can be obtained by using _{S 4} obtained between −π and π [rad].
_{(Ω B1 -ω B2) t 0} = S 4/4 ... (111)
In this way, (ω _{B1- ω B2} ) t ₀ can be uniquely obtained by the equation (111).

Next, by substituting the equations (20), (30), (40) and (50) into the equation (88) _{and setting τ 1} = τ ₂ , the following equation (107) is obtained.
θ _H1 (t) + θ _H2 (t + t ₀ )-{θ _L1 (t + T) + θ _L2 (t + t ₀ + T)}
= 2 (ω _B1 + ω _B2 ) τ ₁ +2 (ω _B1 −ω _B2 ) t ₀ … (107)
Since this equation (107) can be obtained by the remainder system of 2π, if the value on the left side is S ₆ , the following equation (108) can be obtained using _{the integer n 6.
(Ω B1 + ω B2) τ} 1 = S 6/2 + (ω B1 -ω B2) t 0 + n 6 π ... (108)
Since (ω _{B1- ω B2} ) t ₀ can be uniquely obtained from Eq. (111), by substituting this Eq. (111) into Eq. (108), (ω _B1 + ω _B2 ) τ ₁ can be changed to π. It can be obtained with the uncertainty of the cycle.

That is, since τ ₁ = (R / c), instead of directly calculating the equation (98'), (ω _{B1- ω B2} ) t ₀ is obtained from the equations (110) and (111), and (107). ) By substituting into equation (ω _B1 + ω _B2 ) τ ₁ , the maximum distance measurement distance is doubled of the 8-time alternation sequence, that is, the distance is calculated by the above equation (61) in the same manner as the 4-fold alternation sequence. It can be extended to the same maximum distance measurement distance as required.

To obtain equation (110), θ _H1 (t), θ _H1 (t + 2t ₀ ), θ _L1 (t + T), θ _L1 (t + 2t ₀ + T) are detected, and to obtain equation (107), θ _H1 (t). ), θ _H2 (t + t ₀ ), θ _L1 (t + T), θ _L2 (t + t ₀ + T). This means that by measuring the phase in the 6-fold alternation sequence shown in FIG. 26, the distance can be measured up to the maximum distance measurement distance in the 4-fold alternation sequence.

As described above, also in this embodiment, the 6-time alternation sequence is adopted to enable accurate distance measurement, and the communication time can be shortened by about 6/8 times as compared with the 8-fold alternation sequence. be. Further, even in the 6-time alternation sequence, the maximum distance measurement distance can be extended to the same maximum distance measurement distance as when the distance is obtained by the above equation (61).
(Generalization of transmission / reception frequency)
Next, an example of generalizing the transmission / reception frequency will be described.
(Generalization of frequency when phase calculation is calculated at once in 8 alternating sequences)
When the transmitted wave is ω _C + ω _B and ω _C −ω _B , the above equations (84), (20) and (30) are obtained.
θ _H1 (t) + θ _H2 (t + t ₀ ) = θ _τH1 + θ _τH2 + {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ ... (84)
θ _τH1 = (ω _C1 + ω _B1 ) τ ₁ ... (20)
θ _τH2 = (ω _C2 + ω _B2 ) τ ₂ … (30)
When the angular frequency is generalized so that the transmitted wave of the device 1 is ω _C1 + ω _H1 and ω _C1 + ω _L1 and the angular frequency of the transmitted wave of the device 2 _{is replaced with ω C2} + ω _H2 and ω _C2 + ω _L2 , the following (123) )-Equations (130) are established. The detection phase at the generalized angular frequency is expressed as Θ (t).
Θ _H1 (t) + Θ _H2 (t + t ₀ ) = Θ _τ H1 + Θ _{τ H2} + (ω _H1- ω H2) t ₀ + (ω _{C1- ω C2} ) t ₀ … (123)
Θ _H1 (t + t ₀ + D) + Θ _H2 (t + D) = Θ _τH1 + Θ _τH2- (ω _H1 −ω _H2 ) t ₀ − (ω _C1 −ω _C2 ) t ₀ … (124)
Θ _L1 (t + T) + Θ _L2 (t + t ₀ + T) = Θ _τ L1 + Θ _{τ L2} + (ω _L1- ω L2) t ₀ + (ω _{C1- ω C2} ) t ₀ … (125)
Θ _L1 (t + t ₀ + D + T) + Θ _L2 (t + D + T) = Θ _τ L1 + Θ _{τ L2-} (ω _{L1- ω L2} ) t _0- (ω _{C1- ω C2} ) t ₀ ... (126)
_{Θ τH1 = (ω C1 + ω} H1) τ 1 ... (127)
_{Θ τH2 = (ω C2 + ω} H2) τ 2 ... (128)
_{Θ τL1 = (ω C1 + ω} L1) τ 1 ... (129)
_{Θ τL2 = (ω C2 + ω} L2) τ 2 ... (130)
Therefore, the equation corresponding to the equation (98) is given by the following equation (131).
Θ _H1 (t) + Θ _H2 (t + t ₀ ) + Θ _H1 (t + t ₀ + D) + Θ _H2 (t + D)
-{Θ _L1 (t + T) + Θ _L2 (t + t ₀ + T) + Θ _L1 (t + t ₀ + D + T) + Θ _L2 (t + D + T)}
_{= 2 (Θ τH1 -Θ τL1)} +2 (Θ τH2 -Θ τL2)
= 2 (ω _{H1 -ω L1} ) τ ₁ +2 (ω _{H2- ω L2} ) τ ₂ … (131)
Here, the design values of _{ω H1} and ω _{H2 are ω H,} and _{the design values of ω L1} and ω _L2 are ω _L. Considering the target specification of the distance measuring system, omega omega for _{H H1,} error of omega _H2, omega for omega _{L L1,} the error of omega _L2 becomes the order of several 10 [ppm], if a resolution of about 1m Design There is no problem using the value. If τ ₁ = τ ₂ and _{ω H} is used instead of _{ω H1} and ω _{H2 , and ω L is used instead of ω L1} and ω _L2 , the following equation (134) is obtained.
Θ _H1 (t) + Θ _H2 (t + t ₀ ) + Θ _H1 (t + t ₀ + D) + Θ _H2 (t + D)
-{Θ _L1 (t + T) + Θ _L2 (t + t ₀ + T) + Θ _L1 (t + t ₀ + D + T) + Θ _L2 (t + D + T)}
≒ 4 (ω _H − _{ω L} ) τ ₁ … (134)
_{Τ 1} can be obtained by this equation (134), and the distance can be calculated by _{R = cτ 1.}
(Generalization of frequency when dividing phase calculation in 8 alternating sequences)
It was explained that in the 8-fold alternation sequence, the maximum distance measurement distance is halved when the distance is calculated by Eq. (61), but as in the case of the 6-fold alternation sequence, the phase calculation is divided. The maximum distance measurement distance can be extended to the same distance as when the distance is calculated by the equation (61).

When equation (104) is expressed using the generalized angular frequency, it becomes equation (135) below.
Θ _H1 (t) + Θ _H2 (t + t ₀ ) -Θ _H1 (t + t ₀ + D) -Θ _H2 (t + D)
−Θ _L1 (t + T) −Θ _L2 (t + t ₀ + T) + Θ _L1 (t + t ₀ + D + T) + Θ _L2 (t + D + T)
= 2 {(ω _{H1- ω L1} )-(ω _{H2- ω L2} )} t ₀ ... (135)
Since the above equation (135) can be obtained by the remainder system of 2π, if the left side is set to Σ ₈ , the following equation (136) can be obtained using _{the integer m 8.
{(Ω H1 -ω L1) -} (ω H2 -ω L2)} t 0 = (Σ 8/2) + m 8 π ... (136)
Here, as the design values of the device, _{the angular frequency difference between ω H1} and ω _{L1 and} the angular frequency difference between ω _H2 and ω _L2 are set to 2π × 10 [MHz], and the maximum frequency error between transmission and reception is ± 40 [ppm]. If the delay _{t 0} and 0.1 [ms], 360 ° × (10 × 10 6 × ± 40 [ppm]) = so ± 14.4 °, (136) type of left side, - [pi] /. 2 to It is clear that π / 2 [rad] = −90 to 90 °, and uncertainty can be eliminated. That is, the following equation (137) is given using _{Σ 8} obtained between −π and π [rad].
_{{(Ω H1 -ω L1) -} (ω H2 -ω L2)} t 0 = Σ 8/2 ... (137)
In this way, {(ω _{H1- ω L1} )-(ω _{H2- ω L2} )} t ₀ can be uniquely obtained from the equation (137).

The equation corresponding to the above equation (107) is obtained as the following equation (138) as in the case of deriving the equation (134).
Θ _H1 (t) + Θ _H2 (t + t ₀ )-{Θ _L1 (t + T) + Θ _L2 (t + t ₀ + T)}
_{= (Θ τH1 -Θ τL1) +} (Θ τH2 -Θ τL2) + {(ω H1 -ω L1) - (ω H2 -ω L2)} t 0
= 2 (ω _H −ω _L ) τ ₁ + {(ω _H1 −ω _L1 ) − (ω _{H2- ω L2} )} t ₀ … (138)
By substituting the result of Eq. (137) into this Eq. (138), τ ₁ can be obtained, and the distance can be obtained from the distance R = cτ ₁ . In this case, the maximum distance measurement distance that is twice as large as the case where the distance is calculated by the equation (134) can be obtained, and the maximum distance measurement distance can be extended to the same as the case where the distance is calculated by the equation (61).
(Generalization of frequency when phase calculation is divided and calculated in a 6-time alternating sequence)
In the above equation (135), when D = t ₀ , the following equation (139) is obtained.
Θ _H1 (t) -Θ _H1 (t + 2t ₀ ) -Θ _L1 (t + T)-+ Θ _L1 (t + 2t ₀ + T)
= 2 {(ω _{H1- ω L1} )-(ω _{H2- ω L2} )} t ₀ ... (139)
If the result obtained by finding the left side of the equation (139) between −π and π [rad] is Σ ₆ , the uncertainty can be eliminated as in the explanation at the time of deriving the equation (137). The following equation (140) can be obtained.
{(Ω _{H1- ω L1} )-(ω _{H2- ω L2} )} t ₀ = Σ ₆ /2… (140)
By substituting this equation (140) into the equation (138), τ ₁ can be obtained, and the distance can be obtained from the distance R = cτ ₁ .
(Generalization of frequency when phase calculation is calculated at once in a 4-fold alternating sequence)
Similarly, the above equations (116) and (122) are represented by the following equations (141) and (142), respectively, using the design values of the _{angular frequencies ω H} and ω _L.
Θ _H2 (t + 2t ₀ ) +2 Θ _H1 (t + t ₀ ) -Θ _H1 (t)-{Θ _L2 (t + 2t ₀ + T) + 2Θ _L1 (t + t ₀ + T) -Θ _L1 (t + T)}
≒ 2 (ω _H − _{ω L} ) τ ₁ … (141)
Θ _H1 (t) + ₂ Θ H2 (t + t ₀ ) -Θ _H2 (t + 2t ₀ )-{Θ _L1 (t + T) + 2Θ _L2 (t + t ₀ + T) -Θ _L2 (t + 2t ₀ + T)}
≒ 2 (ω _H −ω _L ) τ ₁ … (142)
These (ω _H − _{ω L} ) τ ₁ can be calculated with the uncertainty of the π period as in the equation (117). Therefore, by using the equations (141) and (142), the four-time alternation sequence can be applied to the distance measurement using any two waves or three or more waves.
(Fifth Embodiment) (3 frequency shortened police box sequence)
27 to 29 are explanatory views for explaining the fifth embodiment of the present invention. 27 to 29 show a three-frequency six-time alternation sequence. The hardware configuration in this embodiment is the same as that in the first embodiment. In FIG. 9 described above, an example of extending the distance that can be measured by distance measurement using three transmitted waves has been described. It is conceivable to transmit the transmitted waves of these three frequencies by the same method as the four-time alternating sequence. FIG. 27 shows the transmission signals transmitted from the devices 1 and 2 in the transmission sequence in this case, and FIG. 28 shows the phase detection in the transmission sequence of FIG. 27.

In the present embodiment, as shown in FIG. 27, the device 1 _{generates and transmits the transmission wave ω C1} + ω _H1 , the device 2 generates and transmits the transmission wave ω _C2 + ω _H2 , and the device 1 transmits. The wave ω _C1 + ω _L1 is generated and transmitted, and the device 2 generates and transmits the transmitted wave ω _C2 + ω _L2 . Further, as the third wave, the device 1 _{generates and transmits the transmission wave ω C1} + ω _M1 , and the device 2 generates and transmits the transmission wave ω _C2 + ω _M2 . Since transmission waves of three frequencies are transmitted by alternating them six times, the sequence of FIG. 28 is hereinafter referred to as a three-frequency six-time alternating sequence.

Using τ ₁ = (R / c), the following equation (143) can be obtained from the above equation (141).
(1/2) × Θ _H2 (t + 2t ₀ ) + 2Θ _H1 (t + t ₀ ) −Θ _H1 (t)-{Θ _L2 (t + 2t ₀ + T) +2Θ _L1 (t + t ₀ + T) −Θ _L1 (t + T)}
≒ (ω _H − _{ω L} ) × (R / c)… (143)
Further, it is clear that the equation (144) can be obtained by calculating in the same manner as the above description.
(1/2) × Θ _M2 (t + 2t ₀ + D) + 2Θ _M1 (t + t ₀ + D) -Θ _M1 (t + D)-{Θ _L2 (t + 2t ₀ + T) + 2Θ _L1 (t + t ₀ + T) -Θ _L1 (t + T)}
≒ (ω _M − _{ω L} ) × (R / c)… (144)
In the three-frequency six-time alternating sequence shown in FIG. 28, "the portion from the device 1 _{generating and transmitting the transmitted wave ω C1} + ω _H1 to the reception of _{the transmitted wave ω C2} + ω _H2 transmitted from the device 2". The left side of equation (143) can be calculated from the phase obtained in ”, and this value is described as Θdet. Similarly, from the phase obtained in "the portion _{from the device 1} generating and transmitting the transmission wave ω _C1 + ω _{L1 to the reception of the transmission wave ω C2} + ω _M2 transmitted from the device 2" (144). The left side of the equation can be calculated, and this value is written as Θdet1. By using Θdet and Θdet1, it is possible to extend the distance that can be measured as described with reference to FIG.

Further, in the present embodiment, as shown in FIG. 29, the transmission / reception timing of the third wave is different from that of the sequence of FIG. 28, and the transmission time of the third wave transmission wave ω _C1 + ω _M1 is shortened once. Accurate distance measurement is possible by a 3-frequency 6-time police box sequence (hereinafter, also referred to as a 3-frequency shortened police box sequence) that omits the transmission of. That is, in FIG. 29, the control unit 11 of the device 1 transmits a transmitted wave having an _{angular frequency of ω C1} + ω _{M1 to the device 2 at a timing corresponding to t = D.} The control unit 21 of the device 2 transmits a transmitted wave having an angular frequency of ω _C2 + ω _{M2 at a timing corresponding to t = t 0} + D immediately after receiving the transmitted wave. Further, the control unit 11 of the device 1 _{acquires the phase Θ M2} (t + t ₀ + D) based on the received signal at the _{time t = t 0} + D, and the control unit 21 of the device 2 sets the received signal at the time t = D. Based on this, the phase Θ _M1 (t + D) is acquired.

Hereinafter, the reason why accurate distance measurement is possible by the three-frequency shortened alternating sequence of FIG. 29 will be described.

The following four equations show the above-mentioned equations (27), (37), (47) and (57).
θ _H1 (t) =-{(ω _{C1- ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2- θ _τH1 }… (27)
θ _H2 (t) = (ω _{C1 -ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2 + θ _τH2 … (37)
_{θ L1 (t) = - {} (ω C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) -θ τL1} ... (47)
_{θ L2 (t) = (ω} C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) + θ τL2 ... (57)
In these equations (27), (37), (47) and (57), the angular frequency of the transmitted wave of the device 1 is ω _C1 + ω _H1 , ω _C1 + ω _L1 , and the angular frequency of the transmitted wave of the device 2. Is replaced with ω _C2 + ω _H2 and ω _C2 + ω _L2 and generalized, the following equations (201) to (204) are established using equations (127) to (130).
Θ _H1 (t) =-{(ω _{C1- ω C2} ) t + (ω _{H1- ω H2} ) t + (Θ _{C1- Θ C2} ) + (Θ _{H1- Θ H2} ) -Θ _τ H1}… (201)
Θ _H2 (t) = (ω _{C1 -ω C2} ) t + (ω _{H1- ω H2} ) t + (Θ _{C1- Θ C2} ) + (Θ _{H1- Θ H2} ) + Θ _τ H2… (202)
Θ _L1 (t) =-{(ω _{C1- ω C2} ) t + (ω _{L1- ω L2} ) t + (Θ _{C1- Θ C2} ) + (Θ _{L1- Θ L2} ) -Θ _τ L1}… (203)
Θ _L2 (t) = (ω _{C1 -ω C2} ) t + (ω _{L1- ω L2} ) t + (Θ _{C1- Θ C2} ) + (Θ _{L1- Θ L2} ) + Θ _τ L2… (204)
Similarly, when the third angular frequencies ω _C1 + ω _M1 and ω _C2 + ω _M2 are used, it is clear that the following equations (205) and (206) are established.
Θ _M1 (t) =-{(ω _{C1- ω C2} ) t + (ω _{M1- ω M2} ) t + (Θ _{C1- Θ C2} ) + (Θ _M1 (t) -Θ _M2 ) -Θ _τ M1}… (205)
Θ _M2 (t) = (ω _{C1 -ω C2} ) t + (ω _{M1- ω M2} ) t + (Θ _{C1- Θ C2} ) + (Θ _{M1- Θ M2} ) + Θ _τ M2… (206)
However,
_{Θ τM1 = (ω C1 + ω} M1) τ 1 ... (129a)
_{Θ τM2 = (ω C2 + ω} M2) τ 2 ... (130a)
And.

From the relationship between the above equations (201) to (206), the following equations (207) to (211) are established.
Θ _H1 (t) + Θ _H2 (t + 2t ₀ ) = Θ _{τ H1} + Θ _τ H2 + 2 {(ω _{C1- ω C2} ) + (ω _{H1- ω H2} )} t ₀ ... (207)
Θ _H1 (t + t ₀ ) + Θ _H2 (t + 2t ₀ ) = Θ _τH1 + Θ _τH2 + {(ω _{C1- ω C2} ) + (ω _{H1- ω H2} )} t ₀ … (208)
Θ _L1 (t + T) + Θ _L2 (t + 2t ₀ + T) = Θ _{τ L1} + Θ _τ L2 + 2 {(ω _{C1- ω C2} ) + (ω _{L1- ω L2} )} t ₀ … (209)
Θ _L1 (t + t ₀ + T) + Θ _L2 (t + 2t ₀ + T) = Θ _{τ L1} + Θ _{τ L2} + {(ω _{C1- ω C2} ) + (ω _{L1- ω L2} )} t ₀ … (210)
Θ _M1 (t + D) + Θ _M2 (t + t ₀ + D) = Θ _{τ M1} + Θ _{τ M2} + {(ω _{C1- ω C2} ) + (ω _{M1- ω M2} )} t ₀ … (211)
As described above, the plurality of oscillators in the device 1 oscillate in synchronization with the common reference oscillation source, and the plurality of oscillators in the device 2 also oscillate in synchronization with the common reference oscillation source. It shall be. At this time, if the ideal angular frequencies used as the design values are ω _H , ω _L , and ω _M, and the frequency error between transmission and reception is k, the following equation (212) is established.
k = (ω _{H1 -ω H2} ) / ω _H = (ω _{L1 -ω L2} ) / ω _L = (ω _{M1 -ω M2} ) / ω _M … (212)
When this k is used, the following equations (213) and (214) are established from the equations (207) to (211).
Θ _H1 (t) -Θ _H1 (t + t ₀ ) -Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)
= {(Ω _{H1 -ω H2} )-(ω _{L1- ω L2} )} t ₀
= K (ω _H −ω _L ) t ₀ … (213)
Θ _H1 (t + t ₀ ) + Θ _H2 (t + 2t ₀ )-{Θ _M1 (t + D) + Θ _M2 (t + t ₀ + D)}
_{= Θ τH1 + Θ τH2 -Θ τM1} + Θ τM2 + {(ω H1 -ω H2) - (ω M1 -ω M2)} t 0
_{= Θ τH1 + Θ τH2 -Θ τM1} + Θ τM2 + k (ω H -ω M) t 0 ... (214)
Here, assuming that k is a maximum of ± 40 [ppm], ω _H −ω _L is 2π × 10 [MHz], and delay t ₀ is 0.1 [ms] as the design values of the device, the equation (213) is used. When the right side is calculated, ± 40 [ppm] × 2π × 10 [MHz] × 0.1 [ms]) = ± 0.08π, so the left side of equation (213) can be uniquely obtained without any uncertainty of 2π. .. That is, even if k is about ± 40 [ppm], it can be seen that the uncertainty of 2π on the left side of the equation (213) can be eliminated by appropriately selecting the transmission / reception parameters.

Therefore, the following equation (215) is established from the equations (213) and (214).
Θ _H1 (t + t ₀ ) + Θ _H2 (t + 2t ₀ ) -Θ _M1 (t + D) -Θ _M2 (t + t ₀ + D)
-(Ω _{H- ω M} ) / (ω _{H- ω L} ) {Θ _H1 (t) -Θ _H1 (t + t ₀ ) -Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)}
_{= (Θ τH1 -Θ τM1) +} (Θ τH2 -Θ τM2) ≒ 2 (ω H -ω M) τ 1 ... (215)
Similarly, the following equations (216) are established from the equations (207) to (211).
Θ _L1 (t + t ₀ + T) + Θ _L2 (t + 2t ₀ + T) -Θ _M1 (t + D) -Θ _M2 (t + t ₀ + D)
− (Ω _L −ω _M ) / (ω _H −ω _L ) {Θ _H1 (t) −Θ _H1 (t + t ₀ ) −Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)}
_{= (Θ τL1 -Θ τM1) +} (Θ τL2 -Θ τM2) ≒ 2 (ω L -ω M) τ 1 ... (216)
Further, from the relationship between the equations (201) to (204), the following equation (217) is established.
Θ _H2 (t + 2t ₀ ) +2 Θ _H1 (t + t ₀ ) -Θ _H1 (t)
-{Θ _L2 (t + 2t ₀ + T) + 2Θ _L1 (t + t ₀ + T) -Θ _L1 (t + T)}
_{= (Θ τH1 -Θ τL1) +} (Θ τH2 -Θ τL2) ≒ 2 (ω H -ω L) τ 1 ... (217)
That is, it can be seen that distance measurement is possible by using any combination of the three _{angular frequencies ω H} , ω _L , and ω _M by using the equations (215), (216), and (217).

As described above, in the present embodiment, distance measurement using three frequencies is possible by the same method as the four-time alternation sequence. Then, three types of distance measurement are possible by the three-frequency six-time alternating sequence. In the three-frequency shortening alternating sequence, the phase acquisition by the device 2 at the third frequency may be performed only once, and the transmission time of the device 1 can be shortened. Considering the same, it is possible to shorten the case of 4 waves or more in the same manner. Further, the equation (213) may be obtained from the frequencies obtained by receiving twice each, and does not have to be the first two frequencies. When three or more frequencies are used, one device (for example, device 1) may be "transmitted / received" at two of the frequencies. Since these can be easily inferred from the above, the description thereof will be omitted.
(Sixth Embodiment) (Specific Example of Phase Information Transmission Method)
Next, a sixth embodiment of the present invention will be described. The hardware configuration in this embodiment is the same as that in the first embodiment.

In each of the above embodiments, one of the devices 1 and 2 transmits the phase information based on the acquired I and Q signals to the other, and the other device synthesizes the phase information obtained by the devices 1 and 2. I explained how to find the distance. In this case, if one of the devices 1 and 2 performs data communication separately in order to obtain the phase information measured by the other, the time until the distance measurement is completed is prolonged or the protocol becomes complicated in order to establish the data communication. It is conceivable that This embodiment shows a specific example that enables transmission of phase information without such data communication.

As shown in FIGS. 4 and 5 described above, the device 1 _is capable of input I _{TX1, Q TX1,} apparatus 2 _is capable of input I _{TX2, Q TX2.} In the above-mentioned ( _{transmission / reception of a transmitted wave having an angular frequency of ω C2} + ω _B2 from the device 2), when the device 2 transmits, I _TX2 = 1, Q _TX2 = 0, that is, an IQ signal having a radius of 1 and a phase of 0 degrees. Was explained as giving.

_{Now, in the device 2, it is assumed that θ D2H} or θ D2L is given as a phase offset without changing the input radius 1 and transmitted. This corresponds to shifting the phase of the carrier signal to be transmitted. That is, when the device 2 transmits at the _{angular frequency ω C2} + ω _{B2 , I TX2} = cos (θ _D2H ) and Q _TX2 = sin (θ _D2H ) are input, and the device 2 transmits _{at the angular frequency ω C2- ω B2.} I _TX2 = cos (θ _D2L ) and Q _TX2 = sin (θ _D2L ) are input to. Hereinafter, the transmission / reception signal in this case will be described.

First, phase detection in a transmitted wave having a high angular frequency ω _C2 + ω _{B2 will be described. Assuming that} the initial phases of the angular frequencies ω _C2 and ω _{B2 are θ C2} and θ _{B2 , respectively, the signal tx2 (t) of the angular frequencies ω C2} + ω _B2 transmitted from the device 2 is expressed by the following equation (301). ..
tx2 (t) = cos (ω _C2 t + θ _C2 ) {cos (ω _B2 t + θ _B2 ) cos (θ _D2H ) + sin (ω _B2 t + θ _B2 ) sin (θ _D2H )} − sin (ω _C2 t + θ _C2 ) {sin _B2 t + θ _B2 ) cos (θ _D2H ) -cos (ω _B2 t + θ _B2 ) sin (θ _D2H )}
= Cos (ω _C2 t + θ _C2 ) cos {ω _B2 t + θ _B2 −θ _D2H } − sin (ω _C2 t + θ _C2 ) sin {ω _B2 t + θ _B2 −θ _D2H }
= Cos {(ω _C2 + ω _B2 ) t + θ _C2 + θ _B2- θ _D2H }… (301)
Assuming that the distance between the device 2 and the device 1 is R and the transmitted wave from the device 2 _{is received by the device 1 after the delay time τ 2} , the received signal rx1 (t) is expressed by the following equation (302). NS.
rx1 (t) = cos {( ω C2 + ω B2) (t-τ 2) + θ C2 + θ B2 -θ D2H}
= Cos {(ω _C2 + ω _B2 ) t + θ _C2 + θ _B2- θ _D2H −θ _τH2 }… (302)
Note that θ _τH2 = (ω _C2 + ω _B2 ) τ ₂ ... (303)
Is. Therefore, from the comparison between the above equations (29) and (30) and the above equations (302) and (303), the phase θ _H2 (t) detected by the apparatus 1 is the same as that of the above equation (37). It can be easily inferred that it is given by Eq. (304).
θ _H2 (t) = (ω _{C1 -ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2 + θ _D2H + θ _τH2 … (304)
Next, the phase detection of the transmitted wave having a low angular frequency ω _{C2- ω B2 will be described. The phase θ L2} (t) detected by the device 1 can be obtained by the following equation (305) by considering the same as the derivation of the equation (304) above.
_{θ L2 (t) = (ω} C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) + θ D2L + θ τL2 ... (305)
note that,
θ _τL2 = (ω _{C2 -ω B2} ) τ ₂ … (306)
Is.

Here, consider the case where the distance is measured by the four-time alternating sequence shown in FIG. 17 described above.

Let R be the distance between the device 1 and the device 2, and let τ _{1 be} the delay time until the transmitted wave of the device 1 reaches the device 2. If I _TX1 = 1 and Q _TX1 = 0, the detection phases θ _H1 (t) and θ _L1 (t) in the apparatus 2 are the above equations (20), (27), (40) and (47). Given by. These formulas are reprinted.
θ _τH1 = (ω _C1 + ω _B1 ) τ ₁ ... (20)
θ _H1 (t) =-{(ω _{C1- ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2- θ _τH1 }… (27)
θ _τL1 = (ω _{C1 -ω B1} ) τ ₁ ... (40)
_{θ L1 (t) = - {} (ω C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) -θ τL1} ... (47)
Here, from the above equation (116), by adding the phase information obtained from the received signal in the device 2 to the initial phase and transmitting it to the device 1, the device 1 can measure the distance based on the phase information obtained from the received signal. It is inferred that The analogy will be examined below.

_{Now, it is assumed that the device 2 sets the phase offsets θ D2H} and θ _D2L shown in the following equations (307) and (308) from the detection phase of the received signal.
θ _D2H = 2θ _H1 (t + t ₀ ) −θ _H1 (t)… (307)
θ _D2L = 2θ _L1 (t + t ₀ + T) −θ _L1 (t + T)… (308)
The device 2 performs transmission using _{θ D2H} and θ _D2L calculated based on the phase information obtained from the received signal. The apparatus 1 adds the two phase information obtained from the received signals at the timings of t = 2t ₀ and t = 2t _{0 + T in FIG. 17 to obtain the following equation (309).}
θ _H2 (t + 2t ₀ ) −θ _L2 (t + 2t ₀ + T)
= (Ω _{C1 -ω C2} ) (t + 2t ₀ ) + (ω _{B1- ω B2} ) (t + 2t ₀ ) + θ _C1- θ _C2 + θ _B1- θ _B2 + θ _D2H + θ <sub>τH2
- {(ω C1 -ω C2)</sub> (t + 2t 0 + T) - (ω B1 -ω B2) (t + 2t 0 + T) + θ C1 -θ C2 - (θ B1 -θ B2) + θ D2L + θ τL2}
=-(Ω _{C1 -ω C2} ) T + (ω _{B1- ω B2} ) T + 2 (ω _{B1- ω B2} ) (t + 2t ₀ ) +2 (θ _B1- θ _B2 ) + (θ _τH2- θ _τL2 ) + θ _D2H −θ _D2L … (309)
Here, θ _D2H −θ _D2L is given by the following equation (310).
θ _D2H −θ _D2L
= 2θ _H1 (t + t ₀ ) -θ _H1 (t)-{2θ _L1 (t + t ₀ + T) -θ _L1 (t + T)}
= -2 {(ω _{C1- ω C2} ) (t + t ₀ ) + (ω _{B1- ω B2} ) (t + t ₀ ) + θ _C1- θ _C2 + θ _B1- θ _B2- θ _τH1 }
+ {(Ω _{C1- ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2- θ _τH1 }
_{+2 {(ω C1 -ω C2)} (t + t 0 + T) - (ω B1 -ω B2) (t + t 0 + T) + θ C1 -θ C2 - (θ B1 -θ B2) -θ τL1}
_{- {(ω C1 -ω C2)} (t + T) - (ω B1 -ω B2) (t + T) + θ C1 -θ C2 - (θ B1 -θ B2) -θ τL1}
= (Ω _{C1 -ω C2} ) T- (ω _{B1 -ω B2} ) T-2 (ω _{B1 -ω B2} ) (t + 2t ₀ ) -2 (θ _B1- θ _B2 )-(θ _τH1 −θ _τL1 )… ( 310)
Since the delay of the radio wave between the device 1 and the device 2 is the same regardless of the traveling direction, that is, τ ₁ = τ ₂ , the following equation (311) is established from the above equations (309) and (310).
θ _H2 (t + 2t ₀ ) −θ _L2 (t + 2t ₀ + T) = (θ _τH1 −θ _τL1 ) + (θ _τH2 −θ _τL2 ) = 2 (ω _B1 + ω _B2 ) τ ₁ ... (311)
This equation (311) means that the distance can be measured using only the phase information measured by the device 1. _{That is, if the device 2 transmits using the θ D2H} and θ _D2L given by the equations (307) and (308) based on the measured phase information, the device 1 transmits only the phase information measured by the device 1. It can be seen that it is possible to measure the distance by using it.

As described above, in the present embodiment, one of the devices 1 and 2 transmits a transmission wave in which the phase of the carrier signal to be transmitted is shifted according to the phase obtained based on the measured phase information to the other device. Distance measurement is possible with the other device. As a result, in the present embodiment, it is not necessary to separately communicate the phase information, and it is possible to prevent the time until the completion of distance measurement is prolonged and the protocol becomes complicated.
(Modification example)
Next, a modified example of the sixth embodiment will be described.

It is shown that the above equation (310) also holds when the apparatus 2 sets the _{phase offsets θ D2H} and θ _D2L shown in the following equations (312) and (313) from the detection phase of the received signal.
θ _D2H = 0 ... (312)
θ _D2L = 2θ _L1 (t + t ₀ + T) -θ _L1 (t + T)-{2θ _H1 (t + t ₀ ) -θ _H1 (t)} ... (313)
Even when the device 2 _{transmits the transmitted wave generated by using the θ D2H} and θ _D2L to the device 1, the device 1 can measure the distance using only the measured phase information.

As described above, what kind of phase is given at the time of transmission of the device 2 is a design matter, and the effect of the present embodiment can be obtained even if it is deformed in various ways.

Further, as can be seen from the equation (102), the same effect can be obtained by giving _{the same phase change to θ C2} and θ _B2. Here, as a method of shifting the phase of the carrier signal to be transmitted, the _{phase information given to ITX2 and QTX2} based on the configuration of the radio unit shown in FIGS. 4 and 5 has been described, but other configurations can also be used.

Further, if the same idea is used, it is possible to measure the distance with only the phase information measured by the device 1 in other transmission / reception sequences. That is, the end of the transmission / reception sequence is the transmission from the device 2 to the device 1, and when the device 2 transmits the signal, the device 2 performs a predetermined calculation based on the received phase information, and the phase of the device 2 is calculated based on the result. You may shift the transmission.
(7th Embodiment) (Example of a method of transmitting phase information in a 3-frequency 6-time alternating sequence)
Next, a seventh embodiment of the present invention will be described. The hardware configuration in this embodiment is the same as that in the first embodiment.

As described above, since it is not possible to detect a detection phase difference exceeding 2π, there are a plurality of distance candidates for the calculated detection phase difference. As a method of selecting the correct distance from a plurality of existing distance candidates, the above-mentioned three-frequency six-time alternation sequence of FIG. 28 is shown. This embodiment shows an example in which a separate data communication of phase information is not required in distance measurement using three or more waves, as in this three-frequency six-time alternation sequence.

When the transmitted wave is ω _C + ω _B , ω _C − _{ω B} and the device 2 _{transmits at the angular frequency ω C2} + ω _B2 , the phase offset is I _TX2 = cos (θ _D2H ), Q _TX2 = sin (θ _D2H ). When inputting and transmitting at the angular frequency ω _{C2- ω B2} , it is _{assumed that I TX2} = cos (θ D2L) and Q _TX2 = sin (θ _D2L ) are input. The transmission / reception signal in this case is indicated by the above equations reprinted below.
θ _H1 (t) =-{(ω _{C1- ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2- θ _τH1 }… (27)
θ _H2 (t) = (ω _{C1 -ω C2} ) t + (ω _{B1- ω B2} ) t + θ _C1- θ _C2 + θ _B1- θ _B2 + θ _D2H + θ _τH2 … (304)
_{θ L1 (t) = - {} (ω C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) -θ τL1} ... (47)
_{θ L2 (t) = (ω} C1 -ω C2) t- (ω B1 -ω B2) t + θ C1 -θ C2 - (θ B1 -θ B2) + θ D2L + θ τL2 ... (305)
θ _τH1 = (ω _C1 + ω _B1 ) τ ₁ ... (20)
θ _τH2 = (ω _C2 + ω _B2 ) τ ₂ … (303)
θ _τL2 = (ω _{C2 -ω B2} ) τ ₂ … (306)
θ _τL1 = (ω _{C1 -ω B1} ) τ ₁ ... (40)
First, in order to explain that distance measurement is possible at any two frequencies out of the three frequencies, a distance measurement formula when the angular frequency is generalized will be described.

The angular frequency of the transmitted wave of the device 1 is ω _C1 + ω _H1 , ω _C1 + ω _L1 , ω _C1 + ω _M1 , and the angular frequency of the transmitted wave of the device 2 is ω _C2 + ω _H2 , ω _C2 + ω _L2 , ω _C2 + ω _M2. When 2 transmits at the angular frequency ω _C2 + ω _{H2 , input I TX2} = cos (Θ _D2H ) and Q _TX2 = sin (Θ _D2H ), and when transmitting at the angular frequency ω _C2 + ω _{L2 , I TX2} = cos ( Θ _D2L ), Q _TX2 = sin (Θ _D2L ) is input, and I _TX2 = cos (Θ _D2M ) and Q _TX2 = sin (Θ _D2M ) are input when transmitting at the angular frequency ω _C2 + ω _M2. .. The following equations (320) to (332) are established by calculation in the same manner as in the above description. It should be _{noted that ω H1} > ω _M1 > ω _L1 and the notation of the detection phase at the above generalized angular frequency is Θ (t).
Θ _H1 (t) + Θ _H2 (t + 2t ₀ ) = Θ _τH1 + Θ _τH2 + Θ _D2H + 2 {(ω _{H1- ω H2} ) + (ω _{C1- ω C2} )} t ₀ … (320)
Θ _H1 (t + t ₀ ) + Θ _H2 (t + 2t ₀ ) = Θ _τH1 + Θ _τH2 + Θ _D2H + {(ω _{H1- ω H2} ) + (ω _{C1- ω C2} )} t ₀ … (321)
_{Θ L1 (t + T) +} Θ L2 (t + 2t 0 + T) = Θ τL1 + Θ τL2 + Θ D2L +2 {(ω L1 -ω L2) + (ω C1 -ω C2)} t 0 ... (322)
Θ _L1 (t + t ₀ + T) + Θ _L2 (t + 2t ₀ + T) = Θ _τL1 + Θ _τL2 + Θ _D2L + {(ω _{L1- ω L2} ) + (ω _{C1- ω C2} )} t ₀ … (323)
_{Θ M1 (t + D) +} Θ M2 (t + 2t 0 + D) = Θ τM1 + Θ τM2 + Θ D2M +2 {(ω M1 -ω M2) + (ω C1 -ω C2)} t 0 ... (324)
Θ _M1 (t + t ₀ + D) + Θ _M2 (t + 2t ₀ + D) = Θ _τM1 + Θ _τM2 + Θ _D2M + {(ω _{M1- ω M2} ) + (ω _{C1- ω C2} )} t ₀ … (325)
_{Θ τH1 = (ω C1 + ω} H1) τ 1 ... (326)
_{Θ τH2 = (ω C2 + ω} H2) τ 2 ... (327)
_{Θ τL1 = (ω C1 + ω} L1) τ 1 ... (328)
_{Θ τL2 = (ω C2 + ω} L2) τ 2 ... (329)
_{Θ τM1 = (ω C1 + ω} M1) τ 1 ... (330)
_{Θ τM2 = (ω C2 + ω} M2) τ 2 ... (331)
Here, the device 2 sets the phase offsets shown in the following equations (332) to (334) based on the acquired phase information.
Θ _D2H = 2 _{Θ H1} (t + t ₀ ) −Θ _H1 (t)… (332)
Θ _D2L = 2Θ _L1 (t + t ₀ + T) −Θ _L1 (t + T)… (333)
Θ _D2M = 2 _{Θ M1} (t + t ₀ + D) -Θ _M1 (t + D)… (334)
When transmitting a transmission wave having a phase offset set by the device 2, the above equation (221) × 2- (220) − {(223) equation × 2- (222)} can be calculated and arranged. The following equation (335) can be obtained.
Θ _H2 (t + 2t ₀ ) -Θ _L2 (t + 2t ₀ + T)
_{= (Θ τH1 -Θ τL1) +} (Θ τH2 -Θ τL2)
= (Ω _{H1 -ω L1} ) τ ₁ + (ω _{H2- ω L2} ) τ ₂ … (335)
Here, the angular frequency omega _H1, omega _H2 and omega _L1, omega _L2 their design values omega _H, be replaced by omega _L, considering the target specification of the distance measuring system, omega omega _H1 for _H, the omega _H2 omega _L1 for errors and omega _L, the error of omega _L2 are of the order of a few 10 [ppm], this replacement is not practical problem. Therefore, if τ ₁ = τ _2, and _{ω H} is used instead of _{ω H1} and ω _{H2 , and ω L is used instead of ω L1} and ω _L2 , the following equation (336) is obtained. Be done.
Θ _H2 (t + 2t ₀ ) -Θ _L2 (t + 2t ₀ + T)
≒ 2 (ω _H −ω _L ) τ ₁ … (336)
_{Τ 1} can be obtained from this equation (336), and the distance can be obtained from R = cτ _1.

Similarly, (321) the following x2- (320) formula-{(325) formula x2- (324) formula} and (325) formula x2- (324) formula-{(323) formula x2-( 322) Equation} is calculated and arranged to obtain the following equations (337) and (338).
Θ _H2 (t + 2t ₀ ) -Θ _M2 (t + 2t ₀ + D)
_{= (Θ τH1 -Θ τM1) +} (Θ τH2 -Θ τM2)
= (Ω _{H1 -ω M1} ) τ ₁ + (ω _{H2- ω M2} ) τ ₂
≒ 2 (ω _H − _{ω M} ) τ ₁ … (337)
Θ _M2 (t + 2t ₀ + D) -Θ _L2 (t + 2t ₀ + T)
_{= (Θ τM1 -Θ τL1) +} (Θ τM2 -Θ τL2)
= (Ω _{M1 -ω L1} ) τ ₁ + (ω _{M2- ω L2} ) τ ₂
≒ 2 (ω _M −ω _L ) τ ₁ … (338)
However, the angular frequency ω _M is a design value of the angular frequencies ω _M1 and ω _M2.

The above equations (336) to (338) mean that the device 1 can measure the distance using only the phase information measured by the own device. That is, the apparatus 2 is measured based on the phase information (332) to (334) below at given theta _D2H, theta _D2L, theta by transmitting the transmission waves using the _D2M, device 1 is measured by apparatus 1 It can be seen that it is possible to measure the distance using only the phase information obtained.

As described above, in the present embodiment, even in the three-frequency six-time alternating sequence, one of the devices 1 and 2 transmits a transmission wave in which the phase of the carrier signal to be transmitted is shifted according to the phase obtained based on the measured phase information. By transmitting to the other device, it is possible to measure the distance in the other device without separately communicating the phase information, and it is possible to prevent the time until the completion of the distance measurement is prolonged and the protocol becomes complicated.
(Eighth Embodiment) (Example of a method of transmitting phase information in a three-frequency shortened alternating sequence)
Next, an eighth embodiment of the present invention will be described. The hardware configuration in this embodiment is the same as that in the first embodiment.

As described above, in the three-frequency six-time police box sequence, the three-frequency shortened police box sequence shown in FIG. 29 in which one transmission / reception of the third wave is omitted can be adopted. This embodiment shows an example in which a separate data communication of phase information is not required in this three-frequency shortened alternating sequence.

Even when the three-frequency shortened alternating sequence is adopted, the above equations (320) to (323) and (326) to (329) are satisfied. Further, by using the equations (330) and (331), the following equation (339) is established.
_{Θ M1 (t + D) +} Θ M2 (t + t 0 + D) = Θ τM1 + Θ τM2 + Θ D2M + {(ω M1 -ω M2) + (ω C1 -ω C2)} t 0 ... (339)
As described above, the plurality of oscillators in the device 1 oscillate in synchronization with the common reference oscillation source, and the plurality of oscillators in the device 2 also oscillate in synchronization with the common reference oscillation source. It shall be. At this time, if the ideal angular frequencies are ω _H , ω _L , and ω _M, and the frequency error between transmission and reception is k, the following equation (340) is established.
k = (ω _{H1 -ω H2} ) / ω _H = (ω _{L1 -ω L2} ) / ω _L = (ω _{M1 -ω M2} ) / ω _M … (340)
Here, the device 2 sets the phase offsets shown in the following equations (341) to (343) based on the acquired phase information.
Θ _D2H = 2 _{Θ H1} (t + t ₀ ) −Θ _H1 (t)… (341)
Θ _D2L = 2 _{Θ L1} (t + t ₀ + T) -Θ _L1 (t + T)… (342)
Θ _D2M = Θ _M1 (t + D)-{(ω _{M- ω L} ) / (ω _{H- ω L} )} {Θ _H1 (t) -Θ _H1 (t + t ₀ )}-{(ω _{H- ω M} ) / (Ω _H −ω _L )} {Θ _L1 (t + T) −Θ _L1 (t + t ₀ + T)}… (343)
When transmitting a transmitted wave having a phase offset set by the device 2, it is clear from the comparison between FIGS. 28 and 29 that the above equation (336) holds. Further, (321)-(339)-{(ω _{H- ω M} ) / (ω _{H- ω L} )} {(320)-(321)-(322) + (323)} Is calculated, the following equation (344) is obtained.
Θ _H1 (t + t ₀ ) + Θ _H2 (t + 2t ₀ ) -Θ _M1 (t + D) -Θ _M2 (t + t ₀ + D)
-{(Ω _{H- ω M} ) / (ω _{H- ω L} )} {Θ _H1 (t) -Θ _H1 (t + t ₀ ) -Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)}
_{= Θ τH1 + Θ τH2 + Θ} D2H - {Θ τM1 + Θ τM2 + Θ D2M} + {(ω H1 -ω H2) - (ω M1 -ω M2)} t 0 - {(ω H -ω M) / (ω H - ω _L )} {(ω _{H1- ω H2} )-(ω _{L1- ω L2} )} t ₀ … (344)
By substituting the equations (340), (341) and (343) into the above equation (344), the following equation (345) is obtained.
Θ _H1 (t + t ₀ ) + Θ _H2 (t + 2t ₀ ) -Θ _M1 (t + D) -Θ _M2 (t + t ₀ + D)
-{(Ω _{H- ω M} ) / (ω _{H- ω L} )} {Θ _H1 (t) -Θ _H1 (t + t ₀ ) -Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)}
= Θ _τH1 + Θ _τH2 − (Θ _τM1 + Θ _τM2 ) + {(ω _H1 −ω _H2 ) − (ω _M1 −ω _M2 )} t ₀ − {(ω _H −ω _M ) / (ω _H −ω _L )} {(Ω _{H1- ω H2} )-(ω _{L1- ω L2} )} t ₀ + 2Θ _H1 (t + t ₀ ) -Θ _H1 (t) + {(ω _{M- ω L} ) / (ω _{H- ω L} )} { Θ _H1 (t) -Θ _H1 (t + t ₀ )} + {(ω _{H- ω M} ) / (ω _{H- ω L} )} {Θ _L1 (t + T) -Θ _L1 (t + t ₀ + T)} _{-Θ M1} ( t + D) ... (345)
By _{rearranging using τ 1} = τ ₂ , the following equation (346) is obtained.
Θ _H2 (t + 2t ₀ ) -Θ _M2 (t + t ₀ + D)
_{= (Θ τH1 -Θ τM1) +} (Θ τH2 -Θ τM2)
≒ 2 (ω _H − _{ω M} ) τ ₁ … (346)
Further, (339)-(323)-{(ω _{M- ω L} ) / (ω _{H- ω L} )} {(320)-(321)-(322) + (323)} Is calculated, the following equation (347) is obtained.
Θ _M1 (t + D) + Θ _M2 (t + t ₀ + D) -Θ _L1 (t + t ₀ + T) -Θ _L2 (t + 2t ₀ + T)-{(ω _{M- ω L} ) / (ω _{H- ω L} )} {Θ _H1 ( t) -Θ _H1 (t + t ₀ ) -Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)}
= Θ _τM1 + Θ _τM2 + Θ _D2M- {Θ _τL1 + Θ _τL2 + Θ _D2L } + {(ω _{M1- ω M2} )-(ω _{L1- ω L2} )} t ₀ -{(ω _{M- ω L} ) / (ω _H- ω _L )} {(ω _{M1- ω M2} )-(ω _{L1- ω L2} )} t ₀ … (347)
By substituting the equations (340), (342) and (343) into the above equation (347), the following equation (348) is obtained.
Θ _M1 (t + D) + Θ _M2 (t + t ₀ + D) -Θ _L1 (t + t ₀ + T) -Θ _L2 (t + 2t ₀ + T)-{(ω _{M- ω L} ) / (ω _{H- ω L} )} {Θ _H1 ( t) -Θ _H1 (t + t ₀ ) -Θ _L1 (t + T) + Θ _L1 (t + t ₀ + T)}
= Θ _{τ M1} + Θ _{τ M2} − (Θ _{τ L1} + Θ _{τ L2} ) + {(ω _M1 −ω _M2 ) − (ω _L1 −ω _L2 )} t ₀ − {(ω _M −ω _L ) / (ω _H −ω _L )} {(Ω _{M1- ω M2} )-(ω _{L1- ω L2} )} t ₀ + {(ω _{M- ω L} ) / (ω _{H- ω L} )} {Θ _H1 (t) -Θ _H1 (t + t ₀ ) }-{(Ω _{H- ω M} ) / (ω _{H- ω L} )} {Θ _L1 (t + T) -Θ _L1 (t + t ₀ + T)} + Θ _M1 (t + D) -2Θ _L1 (t + t ₀ + T) + Θ _L1 ( t + T) ... (348)
By _{rearranging using τ 1} = τ ₂ , the following equation (349) is obtained.
Θ _M2 (t + t ₀ + D) -Θ _L2 (t + 2t ₀ + T)
_{= (Θ τM1 -Θ τL1) +} (Θ τM2 -Θ τL2)
≒ 2 (ω _M −ω _L ) τ ₁ … (349)
The above equations (336), (346) and (349) mean that the device 1 can measure the distance using only the phase information measured by the own device. That is, the apparatus 2 is measured based on the phase information (341) to (343) below at given theta _D2H, theta _D2L, theta by transmitting the transmission waves using the _D2M, device 1 is measured by apparatus 1 It can be seen that it is possible to measure the distance using only the phase information obtained.

As described above, in the present embodiment, even in the three-frequency shortened alternating sequence, one of the devices 1 and 2 transmits the transmitted wave in which the phase of the carrier signal to be transmitted is shifted by the phase obtained based on the measured phase information. By transmitting to the device of No. 1, it is possible to measure the distance in the other device without separately communicating the phase information, and it is possible to prevent the time until the completion of the distance measurement is prolonged and the protocol becomes complicated.
(9th embodiment)
30 and 31 are explanatory views showing a ninth embodiment of the present invention. This embodiment shows an example in which each of the above ranging systems is applied to a smart entry system.

In FIG. 30, the key 31 can wirelessly transmit a signal that enables the door of the automobile 32 to be unlocked and locked and the engine of the automobile 32 to be started. That is, the key 31 has a data transmission / reception unit (not shown), and the data transmission / reception unit can transmit encrypted unique data for authentication. The radio wave from the data transmission / reception unit of the key 31 is received by a vehicle control device 35 (not shown) mounted on the automobile 32.

As shown in FIG. 31, the vehicle control device 35 is provided with a control unit 36. The control unit 36 controls each unit of the vehicle control device 35. The control unit 36 may be configured by a processor using a CPU or the like and operate according to a program stored in the memory 38 to control each unit.

The vehicle control device 35 is provided with a data transmission / reception unit 37. The data transmission / reception unit 37 can perform wireless communication with the data transmission / reception unit of the key 31 via the antenna 35a. The data transmission / reception unit 37 receives the unique data transmitted from the key 31 and transmits predetermined response data to the key 31 to authenticate the key 31 and the automobile 32.

The data transmission / reception unit 37 can set the electric field strength in detail, and if the key 31 is not located at a relatively close position where the transmission data of the data transmission / reception unit 37 can be received, that is, in the vicinity of the automobile 32, the authentication is performed. Is not done.

For example, as shown by the broken line in FIG. 30, it is assumed that the key 31 is located sufficiently close to the automobile 32. In this case, the data transmission / reception unit 37 can communicate with each other with the key 31, and the data transmission / reception unit 37 authenticates the key 31 by collating with the unique data recorded in the memory 37a. The data transmission / reception unit 37 outputs a signal indicating that the key 31 has been authenticated to the control unit 36. As a result, the control unit 36 controls the unlocking / locking device 39 to give permission for unlocking and locking.

In FIG. 30, the relay devices 33 and 34 are possessed by the attacker of the relay attack. The relay device 33 can communicate with the key 31, the relay device 34 can communicate with the data transmission / reception unit 37 in the automobile 32, and the relay devices 33 and 34 can communicate with the key 31. The communication with the unit 37 is relayed. As a result, even when the key 31 is sufficiently separated from the automobile 32 as shown in FIG. 30 and the key 31 and the data transmission / reception unit 37 cannot directly communicate with each other, the data transmission / reception can be performed via the relay devices 33 and 34. The unit 37 can authenticate the key 31.

Therefore, in the present embodiment, whether or not the control unit 36 permits unlocking and locking, engine start, and the like based on the authentication result of the data transmission / reception unit 37 and the distance measurement result from the second device 2. It is supposed to decide.

The key 31 has a built-in first device 1 according to each of the above embodiments. On the other hand, the vehicle control device 35 is equipped with the second device 2 according to each of the above embodiments. The transmitted wave from the device 1 is received by the device 2 via the antenna 27a, and the transmitted wave from the device 2 is received by the device 1 via the antenna 27a. The transmitted wave from the device 1 may be directly received by the antenna 27a or may be received by the antenna 27a via the relay devices 33 and 34. Similarly, the transmitted wave from the second device 2 may be received directly from the antenna 27a to the device 1 or may be received from the antenna 27a to the device 1 via the relay devices 34 and 33.

Assuming that the phases of the transmitted waves from the devices 1 and 2 do not change in the relay devices 33 and 34, the device 2 calculates the distance to the key 31 based on the phases obtained in the devices 1 and 2. Can be done. The device 2 outputs the calculated distance to the control unit 36. The memory 38 stores a distance threshold value that allows authentication of the key 31, and the control unit 36 authenticates the key 31 when the distance calculated by the device 2 is within the distance threshold value read from the memory 38. As a result, unlocking and locking, starting the engine, etc. are permitted. Further, the control unit 36 does not allow the authentication of the key 31 when the distance calculated by the device 2 is larger than the distance threshold value read from the memory 38. Therefore, in this case, unlocking and locking, starting the engine, etc. are not permitted.

It is assumed that the relay devices 33 and 34 can change the phase of the transmitted wave from the device 1 and the device 2. Even in this case, since the initial phases of the devices 1 and 2 are unknown, the amount of phase shift required for the distance calculated by the device 2 to be within the distance threshold value read from the memory 38 is set as the relay device. It cannot be obtained at 33 and 34. Therefore, even if the relay devices 33 and 34 are used, the possibility that the authentication of the key 31 is permitted is sufficiently small.

As described above, in the present embodiment, by using the distance measuring system in each of the above embodiments, it is possible to prevent the vehicle from being unlocked or the like by the relay attack on the smart entry system.

The present invention is not limited to the above embodiment, and can be variously modified at the implementation stage without departing from the gist thereof. For example, in FIG. 17, the device 2 is described as receiving the transmission wave of the same frequency transmitted from the device 1 twice, but of course, it may be received more than twice. .. When a signal on which noise or impulse disturbance is superimposed is received, signal processing such as increasing the number of receptions to average or removing abnormal values is generally performed, and the present invention can be applied even in that case. Further, paying attention to the fact that the phase calculation formula for calculating the distance depends on the reception interval t0, various formulas can be modified or combined according to the change in the reception interval, and the reception interval is known. If it is (so-called predetermined interval), it can be easily understood that it is not always necessary to transmit and receive at equal intervals.

In addition, the above-described embodiment includes inventions at various stages, and various inventions can be extracted by an appropriate combination in a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of effect of the invention can be solved. If is obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.

1,2 ... device, 11,21 ... control unit, 12,22 ... memory, 13,23 ... oscillator, 14,24 ... transmitter unit, 15,25 ... receiver unit, 17,27 ... antenna circuit.

Claims (3)

In a distance measuring device that calculates the distance between a first device and a second device that can move at least one of them based on the phases of the first to fourth known signals transmitted at a plurality of carrier frequencies.
The first reference signal source and the output of the first reference signal source are used to correspond to the first known signal corresponding to the first carrier frequency and a second carrier frequency different from the first carrier frequency. A first transmitter / receiver that transmits the second known signal and receives the third known signal corresponding to the first carrier frequency and the fourth known signal corresponding to the second carrier frequency. The first device provided and
A second reference signal source that operates independently of the first reference signal source, the third known signal corresponding to the first carrier frequency using the output of the second reference signal source, and the second reference signal source. The second apparatus including a second transmitter / receiver for transmitting the fourth known signal corresponding to a carrier frequency and receiving the first known signal and the second known signal.
The first phase detector provided in the first device and
A second phase detector provided in the second device and
It is provided in the first device or the second device, and includes a calculation unit for calculating the distance between the first device and the second device.
The first transmitter / receiver and the second transmitter / receiver transmit / receive the first known signal in the first period, transmit / receive the third known signal in the second period, and transmit / receive the first known signal in the third period. Signals are transmitted and received, the second known signal is transmitted and received in the fourth period, the fourth known signal is transmitted and received in the fifth period, and the second known signal is transmitted and received in the sixth period.
The second phase detector detects the first phase of the first known signal during the first period, and the first phase detector detects the second phase of the third known signal during the second period. The second phase detector detects the third phase of the first known signal in the third period, and the second phase detector detects the second phase in the fourth period. The first phase detector detects the fourth phase for the known signal, the first phase detector detects the fifth phase for the fourth known signal during the fifth period, and the second phase detector detects the sixth phase. Detecting the sixth phase for the second known signal during the period,
The calculation unit uses the detected first to sixth phases to perform a difference calculation between the first phase and the fourth phase and a difference calculation between the second phase and the fifth phase. The distance between the first device and the second device is calculated by calculation according to the detection interval of the included phase.
One of the first and second transmitters / receivers adds phase information detected by the first or second phase detector based on a received signal to the other of the first and second transmitters / receivers as a phase offset. A distance measuring device that transmits the known signal generated by the above. In a distance measuring device that calculates the distance between a first device and a second device that can move at least one of them based on the phases of the first to fourth known signals transmitted at a plurality of carrier frequencies.
The first reference signal source and the output of the first reference signal source are used to correspond to the first known signal corresponding to the first carrier frequency and a second carrier frequency different from the first carrier frequency. A first transmitter / receiver that transmits the second known signal and receives the third known signal corresponding to the first carrier frequency and the fourth known signal corresponding to the second carrier frequency. The first device provided and
A second reference signal source that operates independently of the first reference signal source, the third known signal corresponding to the first carrier frequency using the output of the second reference signal source, and the second reference signal source. The second apparatus including a second transmitter / receiver for transmitting the fourth known signal corresponding to a carrier frequency and receiving the first known signal and the second known signal.
The first phase detector provided in the first device and
A second phase detector provided in the second device and
It is provided in the first device or the second device, and includes a calculation unit for calculating the distance between the first device and the second device.
The first transmitter / receiver and the second transmitter / receiver transmit / receive the first known signal in the first period, transmit / receive the third known signal in the second period, and transmit / receive the third known signal in the third period. The known signal is transmitted and received, and the fourth known signal is transmitted and received during the fourth period.
When the first phase detector detects the first phase of the third known signal in the second period, the second phase detector will perform the first phase at predetermined time intervals in the first period. The second and third phases of the first known signal are detected by performing two phase detections, and the second phase detector makes a first phase for the first known signal during the first period. When detecting, the first phase detector detects the second and third phases of the third known signal by performing phase detection twice at a predetermined time interval in the second period. death,
When the first phase detector detects the fourth phase of the fourth known signal in the fourth period, the second phase detector will perform the third period at predetermined time intervals. The phase detection is performed twice to detect the fifth and sixth phases of the second known signal, and the second phase detector performs the fourth phase for the second known signal in the third period. When detecting, the first phase detector detects the fifth and sixth phases of the fourth known signal by performing phase detection twice at a predetermined time interval in the fourth period. death,
The calculation unit uses the detected first to sixth phases to perform a difference calculation between the second phase and the third phase and a difference calculation between the fifth phase and the sixth phase. The distance between the first device and the second device is calculated by calculation according to the phase detection interval including the above.
The first transmitter / receiver uses the output of the first reference signal source to transmit a fifth known signal corresponding to a third carrier frequency different from the first carrier frequency and the second carrier frequency. Upon receiving the sixth known signal corresponding to the third carrier frequency,
The second transmitter / receiver transmits the sixth known signal and receives the fifth known signal by using the output of the second reference signal source.
The first transmitter / receiver and the second transmitter / receiver receive the first transmission / reception of the first and third known signals and the transmission / reception of the second and fourth known signals once, and then the first transmission / reception of the second and fourth known signals. The 5th and 6th known signals are transmitted and received once, respectively.
The second transmitter / receiver receives the fifth known signal twice at predetermined intervals in each transmission / reception of the fifth and sixth known signals.
The second transmitter / receiver omits one of the two receptions of the fifth known signal in each transmission / reception of the fifth and sixth known signals.
One of the first and second transmitters / receivers adds phase information detected by the first or second phase detector based on a received signal to the other of the first and second transmitters / receivers as a phase offset. A distance measuring device that transmits the known signal generated by the above. A distance measuring method that calculates the distance between a first device and a second device that can move at least one of them based on the phases of the first to fourth known signals transmitted at a plurality of carrier frequencies.
The first transmitter / receiver provided in the first apparatus transmits the first known signal corresponding to the first carrier frequency by using the output of the first reference signal source.
A second transmitter / receiver provided in the second apparatus receives the first known signal using the output of the second reference signal source that operates independently of the first reference signal source, and after this reception. A third known signal corresponding to the first carrier frequency is transmitted,
The first transmitter / receiver receives the third known signal using the output of the first reference signal source, and after this reception, uses the output of the first reference signal source to receive the first known signal. Send and
The second transmitter / receiver receives the first known signal using the output of the second reference signal source.
The first transmitter / receiver uses the output of the first reference signal source to transmit a second known signal corresponding to a second carrier frequency different from the first carrier frequency.
The second transmitter / receiver receives the second known signal using the output of the second reference signal source, and after this reception, transmits a fourth known signal corresponding to the second carrier frequency.
The first transmitter / receiver receives the fourth known signal using the output of the first reference signal source, and after this reception, uses the output of the first reference signal source to receive the second known signal. Send and
The second transmitter / receiver receives the second known signal using the output of the second reference signal source.
A second phase detector provided in the second apparatus detects the phase of the first and second known signals received by the second transmitter / receiver.
The first phase detector provided in the first apparatus detects the phase of the third and fourth known signals received by the first transmitter / receiver.
The first device and the calculation unit provided in the first device or the second device are based on the phases of the first to fourth known signals detected by the first and second phase detectors. A distance measuring method for calculating the distance to the second device.

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