JP6912301B2 - Distance measuring device - Google Patents

Description

Embodiments of the present invention relates to a distance measuring equipment.

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 the door 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 in which 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 and the output power is limited by the Radio Law, the distance that can be measured by the distance measuring technology using the reflected wave is relatively small. Not enough to use as a countermeasure.

Japanese Unexamined Patent Publication No. 8-166443

Embodiment, an object to provide a distance measuring equipment capable of a distance between two devices employ a communication distance measuring determined by the communication between the devices to permit calculation of the correct distance.

The distance measuring device of the embodiment is a distance measuring device that calculates a distance based on carrier phase detection, and the first device and the first device are based on phase information acquired by at least one of the movable first device and the second device. It has a calculation unit that calculates the distance between the two devices, and the first device has two or more first devices having different frequencies from each other by using the output of the first reference signal source and the first reference signal source. The second transmitter / receiver includes a first transmitter / receiver that transmits a carrier signal and receives two or more second carrier signals set to the same frequency as each frequency of the two or more first carrier signals. The device transmits the two or more second carrier signals using the output of the second reference signal source that operates independently of the first reference signal source and the output of the second reference signal source, and at the same time, the two or more. The second transmitter / receiver for receiving the first carrier signal of the above is provided, and the calculation unit performs phase calculation using the phase detection result obtained by receiving the first and second carrier signals set to the same frequency. The distance is calculated, and the first and second reference signal sources use the first and second carriers during the period when the first and second carrier signals are transmitted and received by the first and second transmitters and receivers. It operates continuously to continuously change the phase of each signal, and one of the first and second devices is a carrier from the other of the first and second devices. A carrier signal obtained by adding the phase detection result obtained by receiving the signal to the initial phase is generated and transmitted to the other device .

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 demonstrating the principle of distance measurement by a phase detection method using a reflected wave and its problem. Explanatory drawing for demonstrating 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. The circuit diagram which shows an example of the specific structure of the transmission part 14 and the receiving part 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 which transmits the 3rd transmission wave with a different angular frequency 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 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. Explanatory drawing for demonstrating the 2nd Embodiment. The block diagram which shows the 3rd Embodiment of this invention. Explanatory drawing which shows the 4th Embodiment of this invention. Explanatory drawing which shows the 4th Embodiment of this invention. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows various sequences. Explanatory drawing which shows the relationship between a transmission sequence and a period for maintaining an initial phase. Explanatory drawing which shows the carrier frequency used for distance measurement. A flowchart showing a modified example. Explanatory drawing which simplifies an example of the structure of the oscillator 13, the transmission unit 14, and the reception unit 15 of the apparatus 1. The explanatory view which shows a simplified example of the structure of the oscillator 23, the transmission part 24 and the receiving part 25 of apparatus 2. Explanatory drawing which simplifies an example of the structure of the oscillator 13, the transmission unit 14, and the reception unit 15 of the apparatus 1. The explanatory view which shows a simplified example of the structure of the oscillator 23, the transmission part 24 and the receiving part 25 of apparatus 2. FIG. 4 is a circuit diagram specifically showing an example of a circuit for generating signals given to the multipliers TM11 and TM12. FIG. 5 is a circuit diagram specifically showing an example of a circuit for generating signals given to the multipliers TM21 and TM22. The circuit diagram which shows an example of the specific structure of the transmission part 14 and the receiving part 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 circuit diagram which shows an example of the specific structure of the transmission part 14 and the receiving part 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. FIG. 5 is a flowchart showing an example in which the second device transmits phase information to the first device in accordance with FIG. 11A. The flowchart which shows the example corresponding to FIG. 47.

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 reception of one device to the other device, it is possible to obtain an accurate distance in the other device. be.

First, the principle of distance measurement by the phase detection method using reflected waves and its problems will be described with reference to the explanatory diagrams of FIGS. 2A and 2B.
(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.

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 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 of the angular frequency ω _C1 + ω _{B1 is received, and θ L1 be the} amount of phase shift that occurs before the transmission signal of _{the 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 arrival 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 a delay amount of 1 = R / c (s) from the object, and the amplitude is attenuated by the attenuation L1 according to the distance R. Therefore, the following (10) It is represented by an expression.
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 a carrier signal (transmission signal) 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. 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 transmission and reception 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). The component (I signal) and the orthogonal component (Q signal) are separated and demodulated. 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 and Q demodulation processing 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.
(Distance measuring 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 performed 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.
(Constitution)
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 so as to be separated 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 may operate according to a program stored in a memory (not shown) 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.

The transmission unit 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 20. The control unit 21 may be configured by a processor using a CPU or the like, and may operate according to a program stored in a memory (not shown) 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.

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 the local angular frequency for high frequency, here ω _C1 or ω _C2, is the center, and when the higher angular frequency band is demolished, the lower angular frequency band is used. The signal is attenuated, and when the lower angular frequency band is demoted, 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.

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 TM11 and TM12 and an adder TS11. _{Oscillation signals having an angular frequency of ω C1} and phases different from each other by 90 degrees are given to the multipliers TM11 and TM12 from the oscillator 13. _{Further, oscillation signals having angular frequencies of ω B1} and phases different from each other by 90 degrees are given to the multipliers TM11 and TM12, respectively. Further, the multiplier TM12 is also given an inverted signal of an oscillation signal having an _{angular frequency of ω B1 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 adds 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 TM21, TM22, RM21 to RM26 and the adders TS21, RS21, RS22 are the configurations of the multipliers TM11, TM12, RM11 to RM16 and the adders TS11, RS11, RS12 of FIG. 4, respectively. Is similar to. Since the frequency and phase of the oscillation signal of the oscillator 23 are different from those of the oscillator 13, in FIG. 5, the local angular frequency ω _{B2 for the base band is input instead of the angular frequency ω B1} of FIG. 4, and the angular frequency ω of FIG. 4 is input. _The only difference is that ω _{C2 is input instead of C1.} 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.} ..

Further, when transmitting an oscillation signal having an angular frequency of ω _B1 , the control unit 11 generates I and Q signals obtained by adding the phase information of the received signal _{having an angular frequency of ω B2} to the initial phase of the oscillation signal having an angular frequency of ω _B1. 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.

Next, the operation of the embodiment configured in this way will be described with reference to the flowchart of FIG. 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 during 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)}
By a multiplier TM11, TM12 and adder TS11 constituting the transmission unit 14, second transmission wave of angular frequency from the device 1 ω _C1 + ω _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, after ₂ signal tx2 (t) is the delay τ of the angular frequency omega _C2 + omega _B2 transmitted from the device 2, in the case where received by the apparatus 1, is detected by the device 1 I (t), Q ( t) _{The phase θ H2} (t) obtained from the signal is obtained.
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 _{τ L1} = (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 _H1 (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 _H1 (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 _τH1 (t) shown in the above equations (27) and (47). And θ _τL1 (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 _τH2 (Phase θ τH2) shown in the above equations (37) and (57). t) and θ _τL2 (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 equation (58).
{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)
The above equation (61) is a value proportional to twice the distance R by adding 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. Indicates that _{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 −π (rad) or less, or may be larger than π (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 × 5M, 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 ... (62)
Δθ ₂₁ = θ _τH2 −θ _τL2 = −6.0737… (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 and Δθ 12} indicated by the second arrow from the inside, which rotates clockwise with respect to the phase 0 degree, is the addition of _{+ Δθ 21} indicated by the third arrow from the inside. It is shown in the phase (thick broken line) added by the minute (dashed line). 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 + Δθ indicated by the third arrow from the inside. _It is shown in the phase (thick broken line) in which only the added amount (broken line) of 21 is added. 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 a third transmission wave having a different angular frequency and a method of determining by the received power.

FIG. 9 is an explanatory diagram showing an example of transmitting a third transmitted wave having a different angular frequency with a distance on the horizontal axis and a phase on the vertical axis.

From the above equation (61), the following equation (64) can be obtained.
(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, the propagation attenuation of 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 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)
Distinguished from the sum theta _det distances R ₁ and R ₂ between the detected phase difference the received power becomes 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 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 the angular frequencies are set in the first and second devices, respectively. Find the two phases of two different received signals. Then, the obtained phase information is transmitted from 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.
(Second Embodiment)
11A is a flowchart according to the second embodiment of the present invention, and FIGS. 11B to 15B are explanatory views according to the second embodiment. The hardware configuration of this embodiment is the same as that of the first embodiment. Further, the method of transmitting two transmitted waves to each other in the devices 1 and 2 and receiving each other and calculating the distance based on the addition result of the phase difference detected from the received signal is the same as that of the first embodiment.
{Θ _H1 (t) -θ _L1 (t)} + {θ _H2 (t) -θ _L2 (t)} = (θ _τH1- θ _τL1 ) + (θ _τH2- θ _τL2 )… (58)
_{In the first embodiment, 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 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 and received in chronological order, the broken line portion is as shown in FIG. 11A.

Similar to the first embodiment, in the devices 1 and 2 which are separated from each other by a distance R, the phase (shift amount) when the signal of _{the angular frequency ω C1} + ω _{B1 transmitted from the device 1 is detected by the device 2 is θ. H1 , the phase 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 _{L1, and the signal of the angular frequency ω C2} + ω _B2 transmitted from the device 2 is detected in the device 1. Let the phase (shift amount) be θ _{H2, and let θ L2} be the phase when the signal of _{the angular frequency ω C2- ω B2} transmitted from the device 2 is detected by the device 1.

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 (120), 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… (120)
The final term of the above equation (120) is the phase added by time series transmission / reception. This added phase is the result of multiplying the local angular frequency, which is substantially the same as the angular frequency of the received RF (radio 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 too large to measure the distance correctly. I understand.

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 (121).
{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… (121)
The final term of Eq. (121) 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 local frequency is 5 MHz, the frequency error is 40 ppm, and the delay T is 0.1 ms, 360 ° × 0.08 = 28.8 °, which shows that the distance can be measured more accurately than in the previous example.

However, even in this case, whether or not the error amount is within the margin of error of the system specifications 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.
(Specific procedure)
First, consider the effect of transmission delay.

The following equation (122) 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 ) (122)
In addition, here
θ _H1 (t) + θ _H2 (t) = θ _τH1 + θ _τH2 … (123)
θ _L1 (t) + θ _L2 (t) = θ _τL1 + θ _τL2 … (124)
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 transmission 1 after _{t 0 after the device 1 transmits.} The following equation (125) can be obtained from the equations (111) and (112).
θ _H1 (t) + θ _H2 (t + t ₀ ) = θ _τH1 + θ _τH2 + {(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (125)
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 (125). 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 (126) 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 … (126)
The right side of the above equation (126) and the right side of the above equation (125) 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 (127) and (128) 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 ... (127)
θ _L1 (t + T) + θ _L2 (t + t ₀ + T) = θ _τL1 + θ _τL2 + {-(ω _{B1- ω B2} ) + (ω _{C1- ω C2} )} t ₀ … (128)
From the above consideration, consider _{a sequence in which the angular frequency ω C1- ω B1} signal is transmitted and received after the bidirectional transmission and reception of _{the angular frequency ω C1} + ω _B1. 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 the (125) and (128) below Equation (129) 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 … (129)
The final term on the left side of the above equation (129) 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 example, 2π × 5 MHz) for the baseband. 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 (129), which is a factor of the distance estimation error, will be described.

From the above equations (27) and (37), the following equation (130) 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 … (130)
Even if a predetermined delay D is added to the left side of the equation (130), the value on the right side does not change as described above. Therefore, the following equation (131) can be 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 … (131)
By adding the above equations (125) and (131), the following equation (132) 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 )… (132)
The left side of FIG. 14 shows the state of the above equation (132). _{When D = t 0} in this equation (132), the following equation (133) is obtained.
θ _H1 (t) + 2 θ _H2 (t + t ₀ ) + θ _H1 (t + 2t ₀ ) = 2 (θ _τH1 + θ _τH2 )… (133)
The right-hand side of the above equation (133) 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 (134) 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 … (134)
Even if a predetermined delay D is added to the left side of the equation (134), the value on the right side does not change. Therefore, the following equation (135) is 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 … (135)
By adding the above equations (127) and (135), the following equation (136) 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 )… (136)
In this equation (136), when D = t ₀ , the following equation (137) is obtained.
θ _L1 (t) + 2 θ _L2 (t + t ₀ ) + θ _L1 (t + 2t ₀ ) = 2 (θ _{τ L1} + θ _{τ L2} )… (137)
The right-hand side of the above equation (137) is only a term of radio wave propagation delay according to a distance that does not depend on time.

Above (133) and (137) expression system and the phase detection a 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 (136), 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 )… (138)
From the above equations (132) and (138), the following equation (139) 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 … (139)
Above (139) expression 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 (139) 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 (139). 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 present embodiment, 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 first 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.
(Third Embodiment)
FIG. 16 is a block diagram showing a third embodiment of the present invention. FIG. 16 shows a transmitter / receiver used in place of the transmitter / receiver by the transmitter 14 and the receiver 15 of FIG. 4 and the transmitter / receiver by the transmitter 24 and the receiver 25 of FIG. In this embodiment, the configuration of the transmitter / receiver is different from that in the first embodiment.

In the first embodiment, the angular frequency omega _C1 + omega _B1 from the apparatus 1, the phase received by the transmission signal 2 wave device 2 of _{ω C1 -ω B1 θ H1 (t} ), θ L1 a (t) detected, the angular frequency omega _C2 + omega _B2 from the device 2 receives the transmission signal two waves of omega _C2 - [omega] _B2 in apparatus 1 phase theta _H2 (t), to detect the theta _L2 (t), one of these 4 The distance was calculated by using the phase.

However, in general, a bandpass filter (BPF) that suppresses frequencies other than the frequency components near the desired wave is inserted between the transmitter / receiver and the antenna. Since this filter is required to have a steep frequency characteristic, the order is generally high, and therefore the delay of the signal passing through the filter is also large. For example, in the 900 MHz band BPF, a delay of about 10 ns occurs. _{If τ 1} increases by 10 ns due to the delay of the BPF of the transmitter / receiver, the calculated distance will increase by 3 m. Moreover, the delay amount of BPF has a temperature characteristic, and may increase or decrease by 10% or more depending on the surrounding environment. Therefore, the distance cannot be accurately obtained unless the BPF delay time is compensated at the time of distance measurement. The present embodiment compensates for such a delay time of BPF.

In FIG. 16, the multiplier TMIX1 corresponds to the multipliers TM11 and TM21 of FIG. 4 or FIG. Similarly, the multipliers TMIX2, RMIX1 to RMIX6 correspond to the multipliers TM12,22 and the multipliers RM11,21 to RM16,26. Further, the adders TSUM1, RSUM1 and RSMU2 correspond to the adders TS11 and TS21, the adders RS11 and RS21, and the adders RS12 and RS22.

The transmitter including the multipliers TMIX1 and TMIX2 and the adder TSUM1, the receiver including the multipliers RMIX1 to RMIX6 and the adders RSUM1 and RSUM2 adopts the image suppression method as in FIGS. 4 and 5. In the present embodiment, the multipliers RSMIX1 and RSMIX2 are provided in parallel with the multipliers RMIX1 and RMIX2.

The RF (radio frequency) input terminal RX1 is connected to the RX terminal of the switch SW1, the RF output terminal TX1 is connected to the TX terminal of the switch SW1, and the FIL terminal of the switch SW1 is connected to the input terminal of the bandpass filter BPF. The DET terminal of the switch SW2 is connected to the added RF input terminal sRX1, that is, the common input terminal of the multiplier RMIX1 and the multiplier RMIX2, and the FIL_I terminal of the switch SW2 is coupled to the input terminal of the bandpass filter BPF by a coupler (not shown). , The FIL_O terminal of the switch SW2 is coupled to the output terminal of the bandpass filter BPF by a coupler (not shown). The output terminal of the bandpass filter BPF is connected to the antenna ANT terminal. The switches SW1 and SW2 are controlled by the control unit 11 (or the control unit 21).

In the present embodiment, the delay time of the bandpass filter BPF (hereinafter referred to as BPF delay time) is measured and subtracted from the delay time calculated at the time of phase detection to perform accurate distance measurement. ing. The BPF delay time is obtained by giving the transmission signal from the transmitter to the receiver via the switches SW1 and SW2 and obtaining the signal delay time, and by giving the transmission signal from the transmitter to the receiver via the switches SW1 and the bandpass filters BPF and SW2. Obtained by the difference from the signal delay time.

That is, when measuring the BPF delay time, the switch SW1 selects the TX terminal, and the switch SW2 is connected to either the FIL_I terminal or the FIL_O terminal. In this state, the transmitters are operated by the control units 11 and 21, the receiver turns off only the multipliers RMIX1 and RMIX2, and the other circuit blocks are operated.

The BPF delay time is obtained by detecting the transmission signal from the transmitter via the switch SW2 and the multipliers RSMIX1 and RSMIX2. Here, the reason why the multiplier RMIX1 and the multiplier RMIX2 are turned off is to prevent the signal from leaking from the TX terminal of the switch SW1 to the RX terminal and being added to the detection signal to increase the error. If the multiplier RMIX1 and the multiplier RMIX2 are turned off, the isolation of the multiplier RMIX1 and the multiplier RMIX2 is added to the isolation of the switch SW1, so that the signal leaked directly from the transmitter can be significantly attenuated. It will be possible.

In order to detect the BPF delay time, the switch SW2 is first connected to the FIL_I terminal to detect a signal via the FIL_I terminal, and then connected to the FIL_O terminal to detect a signal via the FIL_O terminal. Alternatively, the opposite sequence may be adopted, but here, a case where the connection is made to the FIL_I terminal and then to the FIL_O terminal will be described. The transmitter and receiver for detecting the BPF delay time are in the same device, and a common local signal can be used. Therefore, there is no problem with the initial phase and frequency shift.

Assuming that the angular frequency of the transmitted wave is ω _C1 + ω _B1 and the initial phase is θ _C1 + θ _B1 , the signal of the TX1 terminal is given by the following equation (169).
tx1 (t) = cos {(ω _C1 + ω _B1 ) t + θ _C1 + θ _B1 }… (169)
Since the signal delay due to the switch SW1, the coupler (not shown), and the switch SW2 can be ignored, the signal represented by the equation (169) is input to the multipliers RSMIX1 and RSMIX2. _{The phase θ H1I} (t) detected at this time is obtained by the above equation (27). That is, it is the result of imposing the conditions of _{ω C1} = ω _C2 , ω _B1 = ω _B2 , θ _C1 = θ _C2 , θ _B1 = θ _B2 , and θ _{τH1 = 0.}
θ _H1I (t) = 0 ... (170)
Similarly, assuming that the angular frequency of the transmitted wave is ω _{C1- ω B1} and the initial phase is θ _C1- θ _B1 , the signal at the TX1 terminal is given by the following equation (171).
tx1 (t) = cos {(ω _{C1- ω B1} ) t + θ _C1- θ _B1 }… (171)
Also in this case, the signals input to the multipliers RSMIX1 and RSMIX2 are equal to the equation (171). _{The phase θ L1I} (t) detected in this case can be obtained from the above equation (47). That is, the result is that the conditions of ω _C1 = ω _C2 , ω _B1 = ω _B2 , θ _C1 = θ _C2 , θ _B1 = θ _B2 , and θ _τL1 = 0 are imposed.
θ _L1I (t) = 0 ... (172)
Next, the switch SW2 is connected to the FIL_O terminal. Assuming that the BPF delay is τ _BPF , the two-frequency signals input to the multipliers RSMIX1 and RSMIX2 via the switch SW1, the coupler (not shown), and the switch SW2 are given by the following equations (173) and (174), respectively. ..
rx1 (t) = cos {(ω _C1 + ω _B1 ) t + θ _C1 + θ _B1- θ _BPFH }… (173)
rx1 (t) = cos {(ω _{C1- ω B1} ) t + θ _C1- θ _B1- θ _BPFL }… (174)
here,
θ _BPFH = (ω _C1 + ω _B1 ) τ _BPF … (175)
θ _BPFL = (ω _{C1 -ω B1} ) τ _BPF … (176)
Is. From the above equations (27) and (47), the phases θ _H10 (t) and θ _L10 (t) are represented by the following equations (177) and (178).
θ _H10 (t) = θ _BPFH … (177)
θ _L10 (t) = θ _BPFL … (178)
From the above equations (170), (171), (177), and (178), the following equation (179) is derived.
{Θ _H10 (t) -θ _L10 (t)}-{θ _H1I (t) -θ _L1I (t)} = θ _{BPFH -θ BPFL} = 2ω _B1 τ _BPF ... (179)
The BPF delay time can be obtained by this equation (179). Other configurations and operations are similar to those of the first embodiment. That is, in actual use, the control units 11 and 21 cause the switch SW1 to select the TX terminal at the time of transmission and the RX terminal at the time of reception.

_{The control units 11 and 21 calculate the distance R after correcting τ 1} in the calculation of the above equation (61) with the BPF delay time obtained from the equation (179).

In the above description, the phase of the bandpass filter BPF input end is assumed to be equal to the TX output phase, but if there is a delay in the switch SW, coupler 1, etc., the phase difference including the delay is detected. Will be. However, even in actual use, a signal including a delay of the switch SW1 or the coupler appears at the output end of the bandpass filter BPF and is supplied to the antenna ANT, so that there is a delay up to the input end of the bandpass filter BPF. Even if it does, it can be measured correctly. The control units 11 and 21 may obtain the BPF delay time at the start of actual use, for example.

By the way, a bandpass filter BPF is mainly considered as an environment-dependent element. Therefore, if the phase when the switch SW2 is connected to the FIL_I terminal, that is, the phase at the BPF input end of the bandpass filter that is not easily affected by the environment, is detected in advance and saved in the memory, the subsequent BPF delay There is no problem even if the value saved in the memory is used when calculating the time. That is, in this case, the switch SW2 can always be connected to the FIL_O terminal (bandpass filter BPF output end) after the phase detection at the bandpass filter BPF input end. As a result, it is possible to prevent a sudden change in power and a large spurious generation due to the switching of the switch SW2 during transmission.

As described above, the present embodiment has the advantages that the same effects as those of the above-described embodiments can be obtained, and that the influence of the delay time due to the bandpass filter can be removed to enable accurate distance measurement.

In this embodiment, the multiplier RSMIX1 and the multiplier RSMIX2 used when calculating the BPF delay time are adopted in order to avoid a measurement error due to insufficient isolation of the switch SW1. However, if the isolation of the switch SW1 can be sufficiently obtained, it is also possible to connect the DET terminal of the switch SW2 to the RX1 terminal and measure the delay via the multiplier RMIX1 and the multiplier RMIX2. In this case, at the time of reception, the switch SW1 is connected to the RX1 terminal, and the switch SW2 is connected to or opened from the FIL_I terminal. In this case, the multiplier RSMIX1 and the multiplier RSMIX2 may be omitted.
(Fourth Embodiment)
17 and 18 are explanatory views showing a fourth 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. 17, 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. 18, 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. 17, 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. 17, 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. 17 and direct communication between the key 31 and the data transmission / reception unit 37 cannot be performed, 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 second device 2 according to each of the above embodiments is built in the key 31. On the other hand, the vehicle control device 35 is equipped with the device 1 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 may be directly received from the antenna 27a to the device 1 or may be directly received from the antenna 27a to the device 1 via the relay devices 33 and 34.

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. It is permitted to unlock and lock and start the engine. 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.
(Transmission sequence)
19 to 54 are explanatory views showing various sequences that can be adopted in each of the above embodiments.
(Example of 2 waves)
First, various sequences in which two waves are transmitted from the devices 1 and 2 respectively will be described with reference to FIGS. 19 to 32.

Now, it is assumed that the two transmitted waves output from the device 1 are the transmitted waves A1 and A2, and the frequencies of the transmitted waves A1 and A2 are f _A1 and f _A2 , respectively. Further, it is assumed that the two transmission waves output from the device 2 are the transmission waves B1 and B2, and the frequencies of the transmission waves B1 and B2 are f _B1 and f _B2 , respectively. As described above, in consideration of the existence of frequency bands in which simultaneous transmission / reception is prohibited by the Radio Law, these transmitted waves A1, A2, B1 and B2 should be transmitted in a predetermined sequence in time series. It has become.

FIG. 19 shows a sequence in which carrier sense is performed, there is no response, and there is no repeated alternation.

The device 1 performs _{carrier sense at the frequency f A1} for, for example, 128 μS (seconds), and then transmits the transmitted wave A1. Further, the apparatus 1 transmits the transmission wave A2 after performing carrier sense at the _{frequency f A2 for, for example, 128 μS.}

The device 2 does not respond to the reception of the transmission wave A2 (no response), and after a predetermined period after the transmission of the transmission wave A2 from the device 1, _{performs carrier sense at the frequency f B1} for, for example, 128 μS, and then transmits. Wave B1 is transmitted. Further, the device 2 transmits the transmission wave B2 after performing carrier sense at the _{frequency f B2 for, for example, 128 μS.} The device 2 may reflect the phase detected by the device 2 in the phases of the transmission waves B1 and B2 in a predetermined period (may include a carrier sense period) after the transmission wave A2 from the device 1 is transmitted. good.

An example of this sequence is to determine the presence or absence of a ranging frequency by carrier sense. When it is detected by the carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence described later.

FIG. 20 shows a sequence in which carrier sense is performed, there is no response, and there is a repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Further, the device 1 transmits the transmitted wave A2 after performing carrier sense at the _{frequency f A2} for, for example, 128 μS, without waiting for the response of the transmitted wave from the device 2. _{Further, the device 1 performs carrier sense at the frequency f A1} for, for example, 128 μS without waiting for the response of the transmitted wave from the device 2, and then transmits the transmitted wave A1 again (with repeated alternation).

On the other hand, the device 2 transmits the transmission wave B1 after performing carrier sense at the _{frequency f B1} for, for example, 128 μS, after a predetermined period after the transmission of the transmission wave A2 from the device 1. Further, the device 2 transmits the transmitted wave B2 after performing carrier sense _{at the frequency f B2} for, for example, 128 μS, without the response of the transmitted wave from the device 1. _{Further, the device 2 performs carrier sense at the frequency f B1} for, for example, 128 μS without a response of the transmitted wave from the device 1, and then transmits the transmitted wave B1 again (with repeated alternation).

The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 21 shows a sequence in which carrier sense is performed, there is a response, and there is no repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception.

Further, the device 1 transmits the transmitted wave A2 after performing carrier sense at the _{frequency f A2} for, for example, 128 μS, after a predetermined period after receiving the transmitted wave B1 from the device 2. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 22 shows a sequence in which carrier sense is performed, there is a response, and there is a repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception.

Further, the device 1 transmits the transmitted wave A2 after performing carrier sense at the _{frequency f A2} for, for example, 128 μS, after a predetermined period after receiving the transmitted wave B1 from the device 2. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception.

_{Further, in this example, the device 1 performs carrier sense at the frequency f A1} for, for example, 128 μS after a predetermined period after receiving the transmitted wave B2 from the device 2, and then transmits the transmitted wave A1 again (repeated alternation). Yes). Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 again in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 23 shows a sequence in which carrier sense is performed or not performed, and there is no response and no repeated alternation.

The device 1 continuously transmits the transmitted waves A1 and A2 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.}

The device 2 continuously transmits the transmission waves B1 and B2 after performing carrier sense at the _{frequency f B1} for, for example, 128 μS, after a predetermined period after receiving the transmission wave A2 from the device 1. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

In the example of this sequence, the presence or absence of the ranging frequency is determined by the carrier sense only at the start of transmission. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 24 shows a sequence in which carrier sense is performed or not performed, and there is a response and there is no repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. When the device 1 receives the transmission wave B1 from the device 2, the device 1 transmits the transmission wave A2 without performing carrier sense, for example, 0 μ to 2 seconds after the reception.

Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

In the example of this sequence, the presence or absence of the ranging frequency is determined by the carrier sense only at the start of transmission. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 25 shows a sequence with no carrier sense, no response, and no repetitive alternation.

The device 1 transmits the transmitted wave A1 without performing carrier sense. Further, the device 1 transmits the transmission wave A2 without performing carrier sense several tens of seconds after the transmission of the transmission wave A1. The device 2 transmits the transmission wave B1 without performing carrier sense, for example, 100 msec after receiving the transmission wave A1 from the device 1. Further, the device 2 transmits the transmission wave B2 without performing carrier sense several tens of seconds after the transmission of the transmission wave B1.

FIG. 26 shows a sequence with no carrier sense, no response, and no repetitive alternation.

The device 1 transmits the transmitted wave A1 without performing carrier sense. Further, the device 1 transmits the transmitted wave A2, stops the wave once, and then transmits the transmitted wave A2 without performing carrier sense. In the drawing, the wave stop section is described as 0us to 2ms. Immediately after receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B1 without performing carrier sense. In the drawing, it is described that the transmission wave B1 is transmitted after receiving the transmission wave A2 from the device 1, for example, 2ms from 0us. Further from the device 2, the device 2 transmits the transmission wave B2 after transmitting the transmission wave B1 and then stopping once, and then transmitting the transmission wave B2 without performing carrier sense. In the drawing, the wave stop section is described as 0us to 2ms.

FIG. 27 shows a sequence with no carrier sense, no response, and repeated alternation.

The device 1 transmits the transmitted wave A1 without performing carrier sense. The device 1 transmits the transmission wave A2 without performing carrier sense several tens of seconds after the transmission of the transmission wave A1. Further, the device 1 transmits the transmission wave A1 again without performing carrier sense several tens of seconds after the transmission of the transmission wave A2. The device 2 transmits the transmission wave B1 without performing carrier sense, for example, 100 msec after receiving the transmission wave A1 from the device 1. Further, the device 2 transmits the transmission wave B2 without performing carrier sense, for example, 100 msec after the transmission of the transmission wave B1. Further, the device 2 transmits the transmission wave B1 without performing carrier sense, for example, 100 msec after the transmission of the transmission wave B2.

FIG. 28 shows a sequence with no carrier sense, response, and no repeated alternation.

The device 1 transmits the transmitted wave A1 without performing carrier sense. Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. The device 1 transmits the transmission wave A2 without performing carrier sense several tens of seconds after the transmission of the transmission wave A1. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception.

FIG. 29 shows a sequence with no carrier sense, with response, and with repeated alternation.

The device 1 transmits the transmitted wave A1 without performing carrier sense. Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. The device 1 transmits the transmission wave A2 without performing carrier sense several tens of seconds after the transmission of the transmission wave A1. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. Further, the device 1 transmits the transmission wave A1 again without performing carrier sense several tens of seconds after the transmission of the transmission wave A2. Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 again in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception.

FIG. 30 shows a sequence in which carrier sense is performed or not performed, and there is a response and there is a repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. Apparatus 1 after receiving the transmission waves B1 of a few tens of m seconds after the transmission of the transmission wave A1, after performing inter carrier sense for example 128μS at frequency f _A2, it transmits a transmission wave A2. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. After receiving the transmission wave B1 several tens of seconds after the transmission of the transmission wave A1, the device 1 transmits the transmission wave A1 again without executing carrier sense this time. Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 again in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

In the example of this sequence, the presence or absence of the ranging frequency is determined by the carrier sense only before the repeated alternation. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 31 shows a sequence in which carrier sense is performed or not performed, and there is no response and no repeated alternation.

The device 1 continuously transmits the transmitted waves A1 and A2 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} After receiving the transmission wave A2, the device 2 performs _{carrier sense at the frequency f B1} for, for example, 128 μS, and then continuously transmits the transmission waves B1 and B2. Further, the device 2 continuously transmits the transmission waves B1 and B2 again after performing carrier sense at the _{frequency f B1} for, for example, 128 μS, for example, 100 msec after the transmission of the transmission wave B2. After receiving the transmission wave B2 from the device 2, the device 1 performs _{carrier sense at the frequency f A1} for, for example, 128 μS, and then continuously transmits the transmission waves A1 and A2. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

In the example of this sequence, the presence or absence of the ranging frequency is determined by the carrier sense only at the start of each transmission. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 32 shows a sequence in which carrier sense is performed or not performed, and there is a response and there is no repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. After receiving the transmission wave B1 from the device 2, the device 1 transmits the transmission wave A2 without performing carrier sense. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception.

Further, the device 2 transmits the transmission wave B1 after performing carrier sense at the _{frequency f B1} for, for example, 128 μS, for example, 100 msec after the transmission of the transmission wave B2. When the device 1 receives the transmission wave B1 from the device 2, the device 1 transmits the transmission wave A1 in response to the transmission wave B1 without performing carrier sense. After receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B2 without performing carrier sense. When the device 1 receives the transmission wave B2 from the device 2, the device 1 transmits the transmission wave A2 in response to the transmission wave B2 without performing carrier sense. The device 2 may reflect the received and detected phase in the phases of the transmitted waves B1 and B2 in the spare time until the response.

In the example of this sequence, the presence / absence of the ranging frequency is determined by the carrier sense only at the start of transmission of the devices 1 and 2. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 33 shows a sequence with carrier sense, response, and repeated alternation.

The device 1 transmits the transmission wave A1 after performing carrier sense at the _{frequency f A1 for, for example, 128 μS.} Upon receiving the transmission wave A1 from the device 1, the device 2 transmits the transmission wave B1 in response to the transmission wave B1 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. Further, the device 2 transmits the transmitted wave B1 after _{performing carrier sense at the frequency f B1} for, for example, 128 μS after transmitting the transmitted wave B1. When the device 1 receives the transmission wave B1 from the device 2, the device 1 transmits the transmission wave A1 in response to the transmission wave B1 without performing carrier sense. Further, the device 1 transmits _{the transmitted wave A2 after performing carrier sense at the frequency f A2} for, for example, 128 μS after transmitting the transmitted wave A1. Upon receiving the transmission wave A2 from the device 1, the device 2 transmits the transmission wave B2 in response to the transmission wave B2 without performing carrier sense, for example, 0 μsec to 2 msec after the reception. Further, the device 2 transmits the transmitted wave B2 after _{performing carrier sense at the frequency f B2} for, for example, 128 μS after transmitting the transmitted wave B2. When the device 1 receives the transmission wave B2 from the device 2, the device 1 transmits the transmission wave A2 in response to the transmission wave B2 without performing carrier sense.

An example of this sequence is to determine the presence or absence of a ranging frequency by carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.
(Example of 3 waves)
Next, various sequences in which three waves are transmitted from the devices 1 and 2 respectively will be described with reference to FIGS. 34 to 44.

Now, it is assumed that the three transmitted waves output from the device 1 are the transmitted waves A1, A2, and A3, and the frequencies of the transmitted waves A1, A2, and 3 are f _A1 , f _A2 , and f _A3 , respectively. Further, it is assumed that the three transmitted waves output from the device 2 are the transmitted waves B1, B2 and B3, and the frequencies of the transmitted waves B1, B2 and B3 are f _B1 , f _B2 and f _B3 , respectively. As described above, in consideration of the existence of frequency bands in which simultaneous transmission / reception is prohibited by the Radio Law, these transmitted waves A1 to A3 and B1 to B3 are transmitted in a predetermined sequence. ..

The method of describing the transmission / reception sequence in FIGS. 34 to 44 is the same as that in FIGS. 19 to 32, and the specific transmission / reception sequence will be omitted below.

FIG. 34 shows a sequence in which carrier sense is performed, there is no response, and there is no repeated alternation. An example of this sequence is to determine the presence or absence of a ranging frequency by carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 35 shows a sequence in which carrier sense is performed, there is no response, and there is a repeated alternation. The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 36 shows a sequence in which carrier sense is performed, there is a response, and there is no repeated alternation. The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 37 shows a sequence in which carrier sense is performed, there is a response, and there is a repeated alternation. The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 38 shows a sequence with no carrier sense, no response, and no repetitive alternation.

FIG. 39 shows a sequence with no carrier sense, no response, and repeated alternation.

FIG. 40 shows a sequence with no carrier sense, with response, and without repeated alternation.

FIG. 41 shows a sequence with no carrier sense, with response, and with repeated alternation.

FIG. 42 shows a sequence with and without carrier sense, with response and without repeated alternation. The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 43 shows a sequence in which carrier sense is performed, there is a response, and there is a repeated alternation. The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.

FIG. 44 shows a sequence in which carrier sense is performed, there is a response, and there is a repeated alternation. The example of this sequence also determines the presence or absence of the ranging frequency by the carrier sense. When sensed by carrier sense, (a) it may be started from the beginning again after a predetermined time (for example, several ms), or (b) it may be started by the carrier sense exclusion rule sequence.
(Modification example)
45 to 47 show a modified example. This modification explains the period during which the initial phase should be fixed. FIG. 45 is an explanatory diagram showing the relationship between the transmission sequence and the period for maintaining the initial phase. FIG. 46 is an explanatory diagram showing a carrier frequency used for distance measurement, and FIG. 47 is a flowchart showing a modified example.

In the first embodiment, simultaneous transmission and simultaneous reception of each of the two frequencies from the devices 1 and 2 are assumed. Then, during this transmission / reception period, the oscillators 13 and 23 continue to oscillate so that the initial phase does not change. On the other hand, in the second embodiment, it is defined that only one wave can be transmitted and received between the devices 1 and 2 at the same time, and at least four waves necessary for distance measurement are transmitted and received in chronological order. At the same time, by repeatedly alternating the carrier signals from the devices 1 and 2, accurate distance measurement is possible even when performing time-series transmission / reception.

For example, as described above, in the example of FIG. 15, _{the transmission / reception of the transmission wave of the angular frequency ω C1} + ω _B1 from the device 1, the transmission / reception of the transmission wave of the angular frequency ω _C2 + ω _B2 from the device 2 twice, and the device 1 The transmitted wave of the angular frequency ω _C1 + ω _{B1 from} is transmitted and received.

Further, transmission / reception of the transmission wave of the angular frequency ω _{C1- ω B1} from the device 1, transmission / reception of the transmission wave of the angular frequency ω _{C2- ω B2} from the device 2 twice, and transmission / reception of the transmission wave of the angular frequency ω _{C1- ω B1 from the device 1.} Sends and receives the transmitted wave of.

The phase addition results obtained in the devices 1 and 2 by transmitting and receiving the first four waves in FIG. 15 are shown in the first half portion (first to fourth terms) of the above equation (139). _{The addition result of the first to fourth terms is 2 (θ τH1} + θ _τH2 ) as shown in the above equation (132), and as shown in the above equations (20) and (30), the initial phase Does not include terms. That is, since the phase calculation result obtained by transmitting and receiving the first four waves in FIG. 15 does not include the initial phase information, the calculation of the first to fourth terms in the above equation (139) is performed on these four waves. If the initial phase is not changed only during the transmission / reception period of, the correct result will be obtained.

Similarly, the phase addition results obtained in the devices 1 and 2 by transmitting and receiving the last four waves in FIG. 15 are shown in the latter half of the above equation (139) (paragraphs 5 to 8). _{The addition result of the fifth to eighth terms is 2 (θ τL1} + θ _τL2 ) as shown in the above equation (138), and as shown in the above equations (40) and (50), the initial phase Does not include terms. That is, since the phase calculation result obtained by transmitting and receiving the last four waves in FIG. 15 does not include the initial phase information, the calculation of the fifth to eighth terms in the above equation (139) is performed on these four waves. If the initial phase is not changed only during the transmission / reception period of, the correct result will be obtained.

Figure 45 shows this state, the angular frequency omega _C1 + omega _B1, while maintaining the initial phase constant in the distance measurement period using omega _C2 + omega _B2, an angular frequency _{ω C1 -ω B1, ω C2 -ω} B2 It is shown that the initial phase is kept constant during the ranging period using.

That is, for example, when the sequence of FIG. 15 is adopted, the oscillations of the oscillators 13 and 23 are continued so that the initial phase does not change during the transmission / reception period of the first four waves, and the transmission / reception period of the last four waves. It suffices to continue the oscillation of the oscillators 13 and 23 so that the initial phase does not change in Even if is changed, an accurate distance can be calculated based on the above equation (139).

On the other hand, the oscillator 13, 23 is operated continuously, the initial phase when changing the frequency error in ω _{C +} ω _B ranging section and omega _C - [omega] _B ranging interval changes. That is, _{distance measurement is possible without changing the frequency setting in the ω C} + ω _B distance measurement section, and similarly, distance measurement is possible without changing the frequency setting in the ω _C − _{ω B} distance measurement section. This will be described in detail below (for the two carrier signals).

By the way, in each of the above embodiments, the two carrier signals transmitted by the devices 1 and 2 are, for example, the sum of _{relatively high angular frequencies ω C1} and ω _C2 and, for example, relatively low angular frequencies ω _B1 and ω _B2. An example of the difference frequency is shown. The angular frequencies ω _C1 and ω _C2 are set to substantially the same frequency, and the angular frequencies ω _B1 and ω _B2 are set to substantially the same frequency.
(About two carrier signals)
However, in the distance measurement in each of the above embodiments, the devices 1 and 2 may transmit two carrier signals having a predetermined frequency difference, respectively, as shown below.

The angular frequency ω _C + ω _B and the angular frequency ω _C −ω _B can be transformed as follows.
_{ω C + ω B = (ω} C -Δω C) + (Δω C + ω B) = ω 'C + ω H ... (201)
_{ω C -ω B = (ω C} -Δω C) + (Δω C -ω B) = ω 'C + ω L ... (202)
Now, f _C a transmission wave of angular frequency omega _C and an angular frequency omega _B on the frequency _axis, when expressed as f _B, the transmitted wave of angular frequency ω _{C +} ω _B and the angular frequency omega _C - [omega] _B Figure It is shown on the left side of 46.

Above (201) and (202) below, without changing the frequency, which has changed the representation, transmission waves of angular frequency ω _{C +} ω _B is the angular frequency omega _'C and an angular frequency omega is obtained by the sum of the _H, the transmission wave of the angular frequency omega _C - [omega] _B shows that the angular frequency omega _'C and angular frequency obtained by the sum of the omega _L.

Center of FIG. 46 shows the transmission wave based on this representation, showing angular frequency ω _{C 'C,} ω _H and omega _L f transmission waves on each frequency _axis', f _H, as f _L. A transmission wave of the left frequency _f C -f _B in FIG. 46, the transmission wave of frequency _f C + _{f B,} expressed as a transmission wave 'transmission wave and f the _{C + f L' C + f} H f each identical frequency It shows that it can be done.

That is, in the above equations (201) and (202), the two carriers transmitted by the devices 1 and 2 need not be obtained by the sum and difference of the two frequencies, and the devices 1 and 2 have a predetermined frequency difference. It shows that two carriers having two carriers should be generated and transmitted.

_{As an example of obtaining a transmitted wave having an angular frequency ω C} + ω _B and an angular frequency ω _C −ω _B shown on the left side of FIG. 46, for example, in the oscillators 13 and 23 of FIG. A local signal with an angular frequency of ω _C is generated as a LO frequency) and a local signal with an _{angular frequency of ω B} is generated as a relatively low local frequency (hereinafter, IF-LO frequency). The sum and difference signals of are generated as transmission signals.

In contrast, the transmission wave in the middle of Figure 46 is adapted to generate a local signal of the angular frequency omega _'C as a RF-LO frequency, the angular frequency as the IF-LO frequency omega _L, the two local signals omega _H It is generated and obtained by generating a signal of the sum of these local frequencies as a transmission signal in the transmission units 14 and 24. That is, by fixing the RF-LO frequency and changing the IF-LO frequency, the transmitted wave in the center of FIG. 46 can be obtained.

Further, the angular frequency ω _C − _{ω B} can be deformed as follows.
ω _C −ω _B = (ω _C- 2ω _B ) + (2ω _B −ω _B ) = ω ” _C + ω _B … (203)
The right side of FIG. 46 shows the transmission wave based on the representation of the (203) type, indicating "transmission waves from the _C f on the frequency axis" is the angular frequency ω as _C, the left side of FIG. 46 the frequency f _C - transmission wave f _B indicate that that can be represented as a transmitted wave f "C ₊ f _B of the same frequency.

For example, the right side of the transmission wave of Figure 46 is adapted to generate a local signal and the angular frequency omega "local signal _C of the angular frequency omega _'C as a RF-LO frequency, the angular frequency as the IF-LO frequency is omega _B Local It is obtained by generating a signal and generating a signal of the sum of these local frequencies as a transmission signal at the transmission units 14 and 24. That is, the transmission wave on the right side of FIG. 46 has a fixed IF-LO frequency. Obtained by changing the RF-LO frequency.
(Change of carrier frequency)
In this way, the devices 1 and 2 may transmit two carrier signals having a predetermined frequency difference at the time of distance measurement. Moreover, as in the sequence of FIG. 15, when the transmission and reception of the high frequency carrier of the two carriers is performed alternately, and then the transmission and reception of the low frequency carrier are performed alternately, the high frequency carrier is performed. The initial phase may be different between the transmission and reception of and the transmission and reception of low frequency carriers.

Further, only high frequency carriers are used in the calculation of the above equation (132), which is a decomposition of the above equation (139), and only low frequency carriers are used in the calculation of the above equation (138). That is, the calculation of the above formula (132) and the calculation of the above formula (138) may be performed independently, and the carrier frequency is changed between the transmission / reception period of the high frequency carrier and the transmission / reception period of the low frequency carrier. May be good.

If such a change in the initial phase and a change in the carrier angular frequency are allowed, the flow shown in FIG. 47 can be adopted instead of the flow shown in FIG. 11A.

In the flow of FIG. 47, the first local (LO) frequency is set in the device 1 before the one-wave transmission signal is generated, and the first local is set in the device 2 before the reception of the one-wave transmission wave from the device 1. (LO) Set the frequency. The device 1 uses the local signal of the first LO frequency to generate a high frequency carrier as, for example, a one wave transmission signal, and the device 2 receives the one wave transmission wave using this high frequency carrier and I, Acquire the Q signal.

Further, the device 1 sets the second local (LO) frequency after acquiring the I and Q signals based on the transmitted wave from the device 2 and before generating the next one-wave transmitted signal. Similarly, the device 2 sets the second local (LO) frequency after transmitting the one-wave transmitted wave to the device 1 and before receiving the next one-wave transmitted wave. In the device 1, a carrier having a low frequency is generated by using a local signal having a second LO frequency, for example, as a one-wave transmission signal. Further, the device 2 receives the transmitted wave of the device 1 using the carrier having a low frequency and acquires the I and Q signals.
(Example of oscillator and transmitter / receiver configuration)
As described above, the devices 1 and 2 need only be able to generate and transmit two carrier signals having a predetermined frequency difference, and the oscillators 13 and 23, the transmitting units 14 and 24 and the receiving units 15 and 25 in FIG. 1 are various. A circuit having the above configuration can be adopted.

FIG. 48A is an explanatory diagram showing an example of the configuration of the oscillator 13, the transmitting unit 14, and the receiving unit 15 of the apparatus 1 in a simplified manner. Further, FIG. 48B is an explanatory diagram showing an example of the configuration of the oscillator 23, the transmitting unit 24, and the receiving unit 25 of the device 2 in a simplified manner.

The apparatus 1 and the apparatus 2 include an oscillator that generates an IF-LO frequency and an oscillator that generates an RF-LO frequency, as shown in FIGS. 48A and 48B. The oscillation frequencies of these oscillators are fixed, for example, and by adding or subtracting the IF-LO frequency to the RF-LO frequency, two carrier signals having a frequency difference can be generated.

FIG. 49A is an explanatory diagram showing an example of the configuration of the oscillator 13, the transmitting unit 14, and the receiving unit 15 of the apparatus 1 in a simplified manner. Further, FIG. 49B is an explanatory diagram showing an example of the configuration of the oscillator 23, the transmitting unit 24, and the receiving unit 25 of the device 2 in a simplified manner.

The examples of FIGS. 49A and 49B are examples in which two carrier signals having a frequency difference are generated by a frequency-variable oscillator and a frequency divider (N-div).

Further, FIG. 50 is a circuit diagram specifically showing an example of a circuit for generating signals given to the multipliers TM11 and TM12 in FIG. 4, and FIG. 51 is a circuit diagram showing a signal given to the multipliers TM21 and TM22 in FIG. It is a circuit diagram which shows concretely an example of the circuit which generates.

In Figure 50, the multiplier TM15 gives the result of multiplying the local signal _{cos (ω B1 t + θ B1} ) from _{I T} signal and the oscillator 13 to the adder TS15, multiplier TM16 is from _{Q T} signal and the oscillator 13 The multiplication result with the local signal ± sin (ω _B1 t + θ _B1 ) is given to the adder TS15. The adder TS15 adds two inputs and gives the addition result to the multiplier TM11.

Also, the multiplier TM17 gives the result of multiplying the local signal ± sin from _{I T} signal and the oscillator _{13 (ω B1 t + θ B1} ) to the adder TS16, multiplier TM18 is local from _{Q T} signal and the oscillator 13 The multiplication result with the signal cos (ω _B1 t + θ _B1 ) is given to the adder TS16. The adder TS16 subtracts the output of the multiplier TM18 from the output of the multiplier TM17 and gives the subtraction result to the multiplier TM12. Other configurations are the same as in FIG.

In Figure 51, the multiplier TM25 gives the result of multiplying the local signal _{cos (ω B2 t + θ B2} ) from _{I T} signal and the oscillator 23 to the adder TS25, multiplier TM26 is from _{Q T} signal and the oscillator 23 The multiplication result with the local signal ± sin (ω _B2 t + θ _B2 ) is given to the adder TS25. The adder TS25 adds two inputs and gives the addition result to the multiplier TM21.

Also, the multiplier TM27 gives the result of multiplying the local signal ± sin from _{I T} signal and the oscillator _{23 (ω B2 t + θ B2} ) to the adder TS26, multiplier TM28 is local from _{Q T} signal and the oscillator 23 The multiplication result with the signal cos (ω _B2 t + θ _B2 ) is given to the adder TS26. The adder TS26 subtracts the output of the multiplier TM28 from the output of the multiplier TM27 and gives the subtraction result to the multiplier TM22. Other configurations are the same as in FIG.

FIG. 52 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. 53 is a circuit diagram showing an example of a specific configuration of the transmitting unit 24 and the receiving unit 25 in FIG. Note that FIGS. 52 and 53 show a transmitter / receiver having a heterodyne configuration.

In Figure 52, the multiplier TM1A gives the result of multiplying the local signal _{cos (ω B1 t + θ B1} ) from _{I T} signal and the oscillator 13 to the adder TS1a, multiplier TM1B is from _{Q T} signal and the oscillator 13 The multiplication result with the local signal sin (ω _B1 t + θ _B1 ) is given to the adder TS1A. The adder TS1A subtracts the output of the multiplier TM1B from the output of the multiplier TM1A and gives the subtraction result to the multiplier TM1C. The multiplier TM1C multiplies the output of the adder TS1A and the local signal cos (ω _C1 t + θ _C1 ), and outputs the multiplication result as a transmission signal tx1.

Also, the multiplier RM1A multiplies the received signal rx1 and the local signal _{cos (ω C1 t + θ C1} ) to obtain _{I 1} signal, the multiplier RM1B, and outputs the RM1C. The multiplier RM1B _{outputs the multiplication result of the I 1} signal and the local signal cos (ω _B1 t + θ _B1 ) as an I signal. Further, the multiplier RM1C outputs the multiplication result of the _{I 1} signal and the local signal sin (ω _B1 t + θ _{B1) as a Q signal.}

In Figure 53, the multiplier TM2A gives the result of multiplying the local signal _{cos (ω B2 t + θ B2} ) from _{I T} signal and the oscillator 23 to the adder TS2A, multiplier TM2B is from _{Q T} signal and the oscillator 23 The multiplication result with the local signal sin (ω _B2 t + θ _B2 ) is given to the adder TS2A. The adder TS2A subtracts the output of the multiplier TM2B from the output of the multiplier TM2A and gives the subtraction result to the multiplier TM2C. The multiplier TM2C multiplies the output of the adder TS2A and the local signal cos (ω _C2 t + θ _C2 ), and outputs the multiplication result as a transmission signal tx2.

Also, the multiplier RM2A multiplies the received signal rx2 and the local signal _{cos (ω C2 t + θ C2} ) to obtain _{I 1} signal, the multiplier RM2B, and outputs the RM2C. The multiplier RM2B _{outputs the multiplication result of the I 1} signal and the local signal cos (ω _B2 t + θ _B2 ) as an I signal. Further, the multiplier RM2C outputs the multiplication result of the _{I 1} signal and the local signal sin (ω _B2 t + θ _{B2) as a Q signal.}

Further, FIG. 54 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. 55 is a circuit diagram showing an example of a specific configuration of the transmitting unit 24 and the receiving unit 25 in FIG. In addition, FIG. 54 and FIG. 55 show a transmitter / receiver adopting a direct conversion method.

In Figure 54, the multiplier TM1D gives the result of multiplying the local signal _{cos (ω C1 t + θ C1} ) from _{I T} signal and the oscillator 13 to the adder TS1C, multiplier TM1E is from _{Q T} signal and the oscillator 13 The multiplication result with the local signal sin (ω _C1 t + θ _C1 ) is given to the adder TS1C. The adder TS1C subtracts the output of the multiplier TM1E from the output of the multiplier TM1D and outputs the subtraction result as a transmission signal tx1.

Further, the multiplier RM1D multiplies the received signal rx1 and the local signal cos (ω _C1 t + θ _C1 ) and outputs the multiplication result as an I signal. Further, the multiplier RM1E multiplies the received signal rx1 and the local signal sin (ω _C1 t + θ _C1 ) and outputs the multiplication result as a Q signal.

In Figure 55, the multiplier TM2D gives the result of multiplying the local signal _{cos (ω C2 t + θ C2} ) from _{I T} signal and the oscillator 23 to the adder TS2C, multiplier TM2E is from _{Q T} signal and the oscillator 23 The multiplication result with the local signal sin (ω _C2 t + θ _C2 ) is given to the adder TS2C. The adder TS2C subtracts the output of the multiplier TM2E from the output of the multiplier TM2D and outputs the subtraction result as a transmission signal tx2.

Further, the multiplier RM2D multiplies the received signal rx2 and the local signal cos (ω _C2 t + θ _C2 ) and outputs the multiplication result as an I signal. Further, the multiplier RM2E multiplies the received signal rx2 and the local signal sin (ω _C2 t + θ _C2 ) and outputs the multiplication result as a Q signal.
(Example of transmission of phase information)
In each of the above embodiments, the phase information is transmitted from one of the first device and the second device to the other, but as described above, the method of transmitting the phase information is not particularly limited. .. For example, the phase information may be transmitted by shifting the phase of the carrier signal to be transmitted by the phase obtained from the received signal.

For example, in this case, the broken line portion in FIG. 6 can be replaced with the flow in FIG. 56, and the flow in which steps S7, S8, and S18 in FIG. 6 are omitted can be adopted.

FIG. 56 is a flowchart showing an example in which the second device transmits phase information to the first device in accordance with FIG. 11A. FIG. 56 includes a step of adding the reception phase and the initial phase between the step of acquiring the I and Q signals in the second apparatus of FIG. 11A and the step of generating the one-wave transmission signal. As a result, a carrier signal is generated in which the phase detected from the received signal is added to the initial phase of the device 2. The device 1 can acquire the phase information obtained by the device 2 by receiving the carrier signal from the device 2 and obtaining the phase.

As an extension of the addition of the reception phase and the initial phase, for example, in the 8-time repeating alternation sequence shown in FIG. 15, the sequence of θ _L2 , θ _L2 , and θ _L1 , that is, the signal is sent twice from the device 2 to the device 1. After that, consider the case where a signal is sent from the device 1 to the device 2. The reception phase to be added to the initial phase at the time of the last θ _{L1 transmission may be the phase of the immediately preceding θ L2} , or may be a value in consideration of the phase detection result of the _{previous θ L2.} That is, not only the result received immediately before is reflected, but also the result reflecting the past phase may be added. In this case, generally speaking, adding to the initial phase is the result of performing a predetermined operation on the past detected phase. Further, in the case of the sequence shown in FIG. 15, since the device 2 finally receives the signal, the device 2 becomes a device for calculating the distance. In this case, the device 1 does not necessarily have to calculate the distance.

Further, FIG. 57 is a flowchart showing an example corresponding to FIG. 47. The flow of FIG. 57 includes a step of adding the reception phase and the initial phase between the step of acquiring the I and Q signals in the second apparatus of FIG. 47 and the step of generating the one-wave transmission signal. Assuming the eight-time repeating alternating sequence shown in FIG. 15, a predetermined calculation result with respect to the past detected phase is added to the initial phase as described above. Further, the device 2 becomes a device for calculating the distance. In this way, even when the carrier frequency is changed during distance measurement, the phase information may be included in the phase information of the carrier signal transmitted for distance measurement and transmitted.
(Double the distance measurement distance)
By the way, the result of the above equation (139) is a remainder system of 2π, that is, a value between 0 and 2π. The distance R is R = τ ₁ / C, when obtaining the R and the left side of the (139) type as _{S A,} the following (210) is obtained.
_{R = (S A / 4)} × {c / (ω B1 + ω B2)} ... (210)
The maximum value of _{S A} above (210) formula is 2 [pi, when the _{(ω B1 + ω B2) =} 2πΔf, the maximum value _{R MAX} of the distance R is expressed by the following (211) below.
R _MAX = c / 4Δf ... (211)
That is, the above-mentioned equation (211) is the above-mentioned FIG. 9 in the sequence of FIG. And the maximum distance that can be measured without adopting the method shown in FIG. 10 is shown. On the other hand, when four waves are transmitted at the same time and the distance is obtained by the above equation (61), R _MAX = c / 2Δf. That is, in the eight-time alternating sequence of FIG. 15, the distance that can be measured is half that of the simultaneous transmission of four waves.

Therefore, a method of increasing the distance that can be measured in the eight-time alternating sequence of FIG. 15 will be considered. Now, _{let ω B1- ω B2} be the beat angle frequency, and let A (= 2 (ω _{B1- ω B2} ) t ₀ ) be _{the result of multiplying this beat angle frequency by the time t 0.} A can be obtained by the following equation (212) using the eight measured phases.

A = [mod {(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)) + π, 2π} -π] / 2 ... (212)
Here, when the following equation (213) is satisfied, the distance can be expressed by the following equation (214) by modifying the equation (129).
| 2 (ω _{B1- ω B2} ) t ₀ | ≤ π / 2 ... (213)
R = [{θ _H1 (t) + θ _H2 (t + t ₀ )-(θ _L1 (t + T) + θ _L2 (t + t ₀ + T)) −A} / 2] × c / (ω _B1 + ω _B2 )… (214)
_{Therefore, the maximum value R MAX} of the distance R in this case is expressed by the equation (215).
R _MAX = c / 2Δf ... (215)
That is, by performing distance measurement using the above equation (214), even in the eight-time alternating sequence of FIG. 15, the maximum distance that can be transmitted distance measurement is possible without adopting the method shown in FIGS. 9 and 10 described above. Can be set to the same distance measurement distance as when transmitting four waves at the same time.

For example, if ω _B1 = 2π × 5 [MHz], the error of ω _{B2 with respect to ω B1} is 40 [ppm], and t ₀ = 100 [μs], the left side of the above equation (213) is
2 (ω _{B1- ω B2} ) t ₀ = 2 × 2π × 5 × 40 × ^10-6 × 100 = 0.08π, and it is relatively easy to design the system so as to satisfy the above equation (213). Is.

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. 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 (4)

In a distance measuring device that calculates a distance based on carrier phase detection
It has a calculation unit that calculates the distance between the first device and the second device based on the phase information acquired by at least one of the movable first device and the second device.
The first device is
The first reference signal source and
Using the output of the first reference signal source, two or more first carrier signals having different frequencies are transmitted, and two sets to the same frequency as each frequency of the two or more first carrier signals. A first transmitter / receiver for receiving the above second carrier signal is provided.
The second device is
A second reference signal source that operates independently of the first reference signal source,
A second transmitter / receiver for transmitting the two or more second carrier signals using the output of the second reference signal source and receiving the two or more first carrier signals is provided.
The calculation unit calculates the distance by phase calculation using the phase detection result obtained by receiving the first and second carrier signals set to the same frequency.
The first and second reference signal sources keep the phases of the first and second carrier signals continuous during the period when the first and second carrier signals are transmitted and received by the first and second transmitters and receivers, respectively. Continue to work and change to
One of the first and second devices generates a carrier signal by adding the phase detection result obtained by receiving the carrier signal from the other of the first and second devices to the initial phase. to Ranging device that sends to the other device. The first transmitter / receiver transmits two first carrier signals and receives two or more second carrier signals using the output of the first reference signal source.
The second transmitter / receiver transmits the two or more second carrier signals and receives the two first carrier signals by using the output of the second reference signal source.
The calculation unit calculates the distance based on the four phase detection results obtained by receiving the first and second carrier signals.
One of the first and second devices generates a carrier signal by adding the phase detection result obtained by receiving the carrier signal from the other of the first and second devices to the initial phase. The distance measuring device according to claim 1 , wherein the device is transmitted to the other device. The calculation unit has a first phase difference between the phases of the two second carrier signals obtained by the first transmitter / receiver and a first phase difference of each phase of the two first carrier signals obtained by the second transmitter / receiver. The distance is calculated by adding the two phase differences.
One of the first and second devices generates a carrier signal by adding the phase detection result obtained by receiving the carrier signal from the other of the first and second devices to the initial phase. The distance measuring device according to claim 2 , wherein the device is transmitted to the other device. In a distance measuring device that calculates a distance based on carrier phase detection
It has a calculation unit that calculates the distance between the first device and the second device based on the phase information acquired by at least one of the movable first device and the second device.
The first device is
The first reference signal source and
Using the output of the first reference signal source, two or more first carrier signals having different frequencies are transmitted, and two sets to the same frequency as each frequency of the two or more first carrier signals. A first transmitter / receiver for receiving the above second carrier signal is provided.
The second device is
A second reference signal source that operates independently of the first reference signal source,
A second transmitter / receiver for transmitting the two or more second carrier signals using the output of the second reference signal source and receiving the two or more first carrier signals is provided.
The calculation unit calculates the distance by phase calculation using the phase detection result obtained by receiving the first and second carrier signals set to the same frequency.
The first and second reference signal sources keep the phases of the first and second carrier signals continuous during the period when the first and second carrier signals are transmitted and received by the first and second transmitters and receivers, respectively. Continue to work and change to
The first transmitter / receiver transmits two first carrier signals and receives two or more second carrier signals using the output of the first reference signal source.
The second transmitter / receiver transmits the two or more second carrier signals and receives the two first carrier signals by using the output of the second reference signal source.
The calculation unit calculates the distance based on the eight phase detection results obtained by receiving the first and second carrier signals.
The first transmitter / receiver transmits the first wave of the first carrier signal using the output of the first reference signal source.
The second transmitter / receiver receives the first wave from the first transmitter / receiver using the output of the second reference signal source, and then transmits the first wave of the second carrier signal, and then transmits the first wave of the second carrier signal. After transmitting the first wave of the carrier signal, the first wave of the second carrier signal is transmitted again one hour after the reception of the first wave from the first transmitter / receiver.
The first transmitter / receiver receives the first wave from the second transmitter / receiver twice using the output of the first reference signal source, and then transmits the first wave of the first carrier signal again. After transmitting the first wave of the first carrier signal again, the second wave of the first carrier signal is transmitted two hours after the transmission of the first wave of the first carrier signal.
The second transmitter / receiver receives the first wave and the second wave from the first transmitter / receiver in order using the output of the second reference signal source, and then transmits the second wave of the second carrier signal. Then, after transmitting the second wave of the second carrier signal, the second wave of the second carrier signal is transmitted again one hour after the reception of the second wave from the first transmitter / receiver.
The first transmitter / receiver receives the second wave from the second transmitter / receiver twice using the output of the first reference signal source, and then transmits the second wave of the first carrier signal again.
The second transmitter / receiver is a distance measuring device that receives the second wave from the second transmitter / receiver using the output of the second reference signal source.

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