1. A distance measuring device which employs communication type distance measurement based on a phase detection method, comprising:

a transmission circuit configured to transmit a transmission signal obtained by modulating transmission data, the transmission signal being capable of being transmitted through a plurality of channels used for data communication; and

and a control circuit for controlling the transmission circuit to generate a plurality of continuous waves having different frequencies in the same channel as a continuous wave used for ranging by the phase detection method.

2. The ranging apparatus of claim 1,

the transmission circuit obtains the transmission signal by FSK modulation,

the distance measuring device includes a distance measuring signal transmission processing circuit for generating consecutive 1 s and consecutive 0 s as the transmission data and applying the generated consecutive 1 s and consecutive 0 s to the transmission circuit,

in the ranging mode, the control circuit causes the ranging signal transmission processing circuit to generate successive 1 s and successive 0 s and supply them to the transmission circuit in order to generate a plurality of continuous waves in the same channel.

3. The ranging apparatus of claim 2,

the ranging signal transmission processing circuit gives the consecutive 1 and the consecutive 0 to the transmission circuit in a time-division manner,

the transmission circuit generates a continuous wave based on the continuous 1 and a continuous wave based on the continuous 0 in the same channel in a time division manner.

4. A ranging system in which, in a ranging system,

comprising a plurality of distance measuring devices according to claim 1,

the plurality of ranging devices transmit and receive a plurality of continuous waves having different frequencies in the same channel to obtain a ranging result.

5. The ranging system of claim 4,

the method includes correcting the folding back of the ranging result obtained by generating a plurality of continuous waves using the plurality of channels and transmitting and receiving the plurality of continuous waves between the plurality of ranging devices, using the ranging result obtained by transmitting and receiving the plurality of continuous waves in the same channel between the plurality of ranging devices.

6. A distance measurement method adopts communication type distance measurement based on a phase detection mode, wherein,

consecutive 1 s and consecutive 0 s are generated as transmission data,

the continuous 1 and the continuous 0 are applied to a transmission circuit which performs FSK modulation on transmission data and transmits a transmission signal, thereby generating a plurality of continuous waves having mutually different frequencies in a predetermined channel among a plurality of channels for data communication as a transmission signal for ranging.

Background

Conventionally, the distance measurement system includes a time detection system, a frequency difference detection system, a phase detection system, and the like, but a distance measurement system using a communication type phase detection system for obtaining a distance between devices by communication between the devices is attracting attention from the viewpoint of ease of installation.

It is conceivable to incorporate such a ranging system into a data communication device employed in a portable terminal or the like. However, when a circuit for data communication and a circuit for distance measurement are combined, the circuit scale increases.

Further, when a signal for ranging is transmitted using a channel for data communication, there is a disadvantage that a distance over which ranging can be performed is short because a channel interval for data communication is generally large.

Disclosure of Invention

Embodiments provide a ranging apparatus, a ranging system, and a ranging method, which can perform ranging and data communication while suppressing an increase in circuit scale by sharing a receiver circuit and can perform ranging over a relatively long distance.

A distance measuring device of an embodiment employs communication type distance measurement based on a phase detection method, and the distance measuring device includes: a transmission circuit configured to transmit a transmission signal obtained by modulating transmission data, the transmission signal being capable of being transmitted through a plurality of channels used for data communication; and a control unit configured to control the transmission circuit to generate a plurality of continuous waves having different frequencies in the same channel as a continuous wave used for ranging by the phase detection method.

Drawings

Fig. 1 is a block diagram showing a distance measuring device according to an embodiment of the present invention.

Fig. 2 is an explanatory diagram for explaining an example of a ranging system for performing communication-type ranging.

Fig. 3 is an explanatory diagram showing an example of transmission signals of the device 30 and the device 40.

Fig. 4 is an explanatory diagram for explaining frequency components of the ranging signal.

Fig. 5 is a flowchart for explaining the operation of the embodiment.

Fig. 6 is an explanatory diagram for explaining a modification.

Detailed Description

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

(embodiment mode)

Fig. 1 is a block diagram showing a distance measuring device according to an embodiment of the present invention. The distance measuring device of the present embodiment is also a data communication device using FSK (Frequency Shift Keying) modulation, and is configured to share a transmission/reception circuit in a circuit part for distance measurement and a circuit part for data communication. In the present embodiment, a relatively long distance ranging is possible by using a plurality of CWs (Continuous waves) in a frequency band within 1 channel of a transmission channel used for data communication for ranging.

In this embodiment, an example of communication type ranging in which a phase detection method using CW that is an unmodulated carrier is used to obtain a distance between devices by communication will be described.

Fig. 2 is an explanatory diagram for explaining an example of a ranging system for performing communication-type ranging. The ranging system of fig. 2 is a system for ranging a distance between the devices 30 and 40 through communication between the ranging devices 30 and 40.

The apparatus 30 and the apparatus 40 have the same configuration. The device 30 includes a transmission unit 32 and a reception unit 33. The transmitter 32 generates CW (hereinafter, also referred to as a ranging signal) for ranging. The ranging signal from the transmitter 32 is supplied to the antenna 34 via the switch 35, and is transmitted to the device 40. Further, the ranging signal from device 40 reaches antenna 34 of device 30. The ranging signal is supplied to and received by the receiving unit 33 via the switch 35.

The transmission unit 42, the reception unit 43, the antenna 44, and the switch 45 of the device 40 have the same configurations as the transmission unit 32, the reception unit 33, the antenna 34, and the switch 35 of the device 30, respectively. Thereby, the ranging signal from device 30 is received at device 40, and the ranging signal from device 40 is received at device 30.

The digital units 31 and 41 have the same configuration, and control the respective units of the device 30 and the device 40. That is, the digital unit 31 causes the transmission unit 32 to generate a ranging signal to be transmitted to the device 40, and causes the reception unit 33 to receive the ranging signal from the device 40. Similarly, digital unit 41 causes transmission unit 42 to generate a ranging signal to be transmitted to device 30, and causes reception unit 43 to receive the ranging signal from device 30.

(example of distance measurement calculation)

Next, an example of the distance measurement calculation will be described with reference to the method described in japanese patent laid-open publication No. 2018-155724 (hereinafter, referred to as a prior art document).

Device 30 and device 40 transmit and receive frequency f to each other_LAnd a distance measurement signal (CW) as a non-modulated carrier, and mutually transmit and receive the frequency f_HI.e. the ranging signal (CW). Using the angular frequency ω of the oscillation signal generated by the oscillator, not shown, of the device 30, 40_B、ω_CIs set to a frequency of 2 pi f_L＝ω_C-ω_BAnd is expressed as 2 pi f_H＝ω_C+ω_B. The frequencies of oscillation signals of oscillators, not shown, of the devices 30 and 40 are not strictly the same. Taking this deviation into account, the device 30 transmits an angular frequency ω_C1+ω_B1And the angular frequency of_C1-ω_B1The transmission signal of 2 waves. Likewise, the device 40 transmits an angular frequency ω_C2+ω_B2And the angular frequency of_C2-ω_B2The transmission signal of 2 waves. The devices 30, 40 receive a transmission signal from each other.

Further, the angular frequency of the device 30 is set to ω_C1Has an initial phase of theta_C1Frequency of ω_B1Has an initial phase of theta_B1Angular frequency of the device 40 is ω_C2Has an initial phase of theta_C2Frequency of ω_B2Has an initial phase of theta_B2。

Will be delayed in the arrangement 40 by tau₁And then receives the angular frequency ω in the transmission signal transmitted from the device 30 to the device 40_C1+ω_B1The amount of phase shift generated before the transmission of the signal is set to theta_H1(t) the angular frequency ω will be received in the device 40_C1-ω_B1The amount of phase shift generated before the transmission of the signal is set to theta_L1(t)。

Also, τ will be delayed in device 30₂And then receives the angular frequency ω in the transmission signal transmitted from the device 40 to the device 30_C2+ω_B2The amount of phase shift generated before the transmission of the signal is set to theta_H2(t) the angular frequency ω will be received in the device 30_C2-ω_B2The amount of phase shift generated before the transmission of the signal is set to theta_L2(t)。

In this case, the following expression (1) is shown to be established in the prior art document.

{θ_H1(t)-θ_L1(t)}+{θ_H2(t)-θ_L2(t)}

＝(θ_τH1-θ_τL1)+(θ_τH2-θ_τL2)……(1)

Wherein the content of the first and second substances,

θ_τH1＝(ω_C1+ω_B1)τ₁……(2)

θ_τH2＝(ω_C2+ω_B2)τ₂……(3)

θ_τL1＝(ω_C1-ω_B1)τ₁……(4)

θ_τL2＝(ω_C2-ω_B2)τ₂……(5)

delay τ of radio wave between device 30 and device 40₁、τ₂Since the same is true regardless of the traveling direction, the following expression (6) can be obtained from expression (1).

{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)τ₁……(6)

When the speed of the radio wave is c, the distance between the device 30 and the device 40 is R, and the delay time is τ, τ is R/c. By substituting this into the formula (6), the following formula (7) can be obtained.

(1/2)×{(θ_τH1-θ_τL1)+(θ_τH2-θ_τL2)}

＝(ω_B1+ω_B2)×(R/c)……(7)

As can be seen from equation (7), the angular frequency ω can be determined_B1、ω_B2And the distance R between the device 30 and the device 40 is calculated as the result of adding the phase difference obtained from the 2 frequencies received by the device 30 and the phase difference obtained from the 2 frequencies received by the device 40.

Equation (7) above is an example of a case where the devices 30 and 40 perform transmission and reception processes simultaneously. However, according to the regulations of the japanese radio wave act, there are frequency bands in which transmission and reception cannot be performed simultaneously. Therefore, an example corresponding to the case of time-series transmission and reception is disclosed in the prior art document.

Fig. 3 is an explanatory diagram showing an example of transmission signals of the device 30 and the device 40 in this case by arrows. In the sequence shown in fig. 3, the following expression (8) holds. Here, t₀D, T shows the delay time shown in fig. 3.

θ_H1(t)+θ_H2(t+t₀)+θ_H1(t+t₀+D)+θ_H2(t+D)

-{θ_L1(t+T)+θ_L2(t+t₀+T)+θ_L1(t+t₀+D+T)+θ_L2(t+D+T)}

＝2{(θ_τH1-θ_τL1)+(θ_τH2-θ_τL2)}＝4×(ω_B1+ω_B2)τ₁……(8)

That is, in the sequence of fig. 3, the device 30 transmits an angular frequency ω at a predetermined timing_C1+ω_B1The transmission wave (hereinafter, referred to as transmission wave H1A). The device 40 transmits an angular frequency ω immediately after receiving the transmitted wave H1A_C2+ω_B2The transmission wave of (2) (hereinafter, referred to as transmission wave H2A). Further, after transmitting the transmission wave H2A, the device 40 transmits the angular frequency ω again_C2+ω_B2The transmission wave of (2) (hereinafter, referred to as transmission wave H2B). Device 30 transmits angular frequency ω again after receiving transmission wave H2B of 2 nd time_C1+ω_B1The transmission wave (hereinafter, referred to as transmission wave H1B).

Further, the device 30 transmits an angular frequency ω_C1-ω_B1The transmission wave of (2) (hereinafter, referred to as transmission wave L1A). The device 40 transmits an angular frequency ω immediately after receiving the transmitted wave L1A_C2-ω_B2The transmission wave of (2) (hereinafter, referred to as transmission wave L2A). Further, after transmitting the transmission wave L2A, the device 40 transmits the angular frequency ω again_C2-ω_B2The transmission wave of (2) (hereinafter, referred to as transmission wave L2B). The device 30 transmits again the angular frequency ω after receiving the 2 nd transmission wave L2B_C1-ω_B1The transmission wave of (2) (hereinafter, referred to as transmission wave L1B).

Thus, as shown in fig. 3, the device 40 acquires the phase θ based on the transmission wave H1A at a predetermined time from the predetermined reference time 0_H1(t) at a time t₀The phase θ of the transmission wave H1B is obtained at a predetermined time from + D_H1(t+t₀+ D), and the phase θ of the transmission wave L1A is acquired at a predetermined time from the time T_L1(T + T) at a time T₀The phase θ based on the transmitted wave L1B is obtained at a predetermined time from + D + T_L1(t+t₀+D+T)。

Furthermore, device 30 is operating at slave time t₀The phase theta of the transmission wave H2A is obtained at a predetermined time_H2(t+t₀) The phase θ based on the transmission wave H2B is acquired at a predetermined time from the time D_H2(t + D) at the slave time t₀Acquisition at a predetermined time from + TPhase θ based on transmission wave L2A_L2(t+t₀+ T), and the phase θ based on the transmission wave L2B is acquired at a predetermined time from the time D + T_L2(t+D+T)。

At least one of the devices 30 or 40 transmits phase information, that is, the calculated 4 phases or 2 phase differences or the calculation result of the above equation (8) of the phase difference to the other. The control unit of the device 30 or 40 that receives the phase information calculates the distance by the calculation of the above-described expression (8).

(constitution)

Fig. 1 shows an example of a specific configuration of the apparatus 30 (or 40) shown in fig. 2. The transmission/reception circuit 20 corresponds to the transmission units 32 and 42 and the reception units 33 and 43 in fig. 2. In fig. 1, the digital units 31 and 41 in fig. 2 are configured by the control unit 11, the transmission data processing unit 12, the ranging signal transmission processing unit 13, the reception data processing unit 14, the ranging processing unit 15, and the switches 16 and 17.

The control unit 11 controls each unit of the distance measuring apparatus of fig. 1. The control Unit 11 may be configured by a processor using a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or the like, and may control each Unit by operating according to a program stored in a memory (not shown), or may realize a part or all of the functions by an electronic circuit of hardware.

The transmission data processing unit 12 and the reception data processing unit 14 are respectively configured by a transmission data processing circuit and a reception data processing circuit for data communication, and the ranging signal transmission processing unit 13 and the ranging processing unit 15 are respectively configured by a ranging signal transmission processing circuit and a ranging processing circuit for ranging. The transceiver circuit 20 is a circuit commonly used for data communication and ranging.

The output of the transmission data processing unit 12 and the output of the ranging signal transmission processing unit 13 are supplied to the transmission/reception circuit 20 via the switch 16. The switch 16 is controlled by the control unit 11, and selectively applies the output of the transmission data processing unit 12 or the output of the ranging signal transmission processing unit 13 to the transmission/reception circuit 20.

The transmission data processing unit 12 is controlled by the control unit 11, generates transmission data, and outputs the transmission data to the switch 16. The switch 16 selects the output of the transmission data processing unit 12 at the time of data communication and outputs the selected output to the transmission/reception circuit 20.

The transceiver circuit 20 performs the following processing: a transmission signal is generated by FSK modulation, and a reception signal is FSK demodulated to generate a baseband signal. That is, the data generator 21 of the transmitting/receiving circuit 20 is given transmission data via the switch 16. The data generator 21 generates data for FSK modulation based on the transmission data and outputs to the oscillator 22. The oscillator 22 changes the oscillation frequency in accordance with the input data.

In this manner, the transmission data is FSK modulated to obtain a transmission signal from the oscillator 22. In addition, the oscillator 22 can generate transmission signals of a plurality of frequencies corresponding to a plurality of channels. The control unit 11 can control the frequency (channel) of the transmission signal generated by the oscillator 22.

The output of the oscillator 22 is given to a power amplifier 23. The power amplifier 23 amplifies the transmission signal and outputs the amplified signal to the antenna 25 via the switch 24. The switch 24 is controlled by the control unit 11, and connects the power amplifier 23 to the antenna 25 at the time of transmission, and connects the antenna 25 to the received signal acquisition unit 26 at the time of reception. In this manner, at the time of transmission, the antenna 25 transmits the transmission signal from the power amplifier 23.

The antenna 25 receives a reception signal at the time of reception, and gives the reception signal to the reception processing unit 26 via the switch 24. The reception processing unit 26 performs FSK demodulation processing on the received signal and outputs a demodulated signal.

The demodulated signal from the reception processing unit 26 of the transceiver circuit 20 is supplied to the switch 17. The switch 17 is controlled by the control unit 11, and selectively supplies the output of the reception processing unit 26 to the reception data processing unit 14 or the ranging processing unit 15. The switch 17 outputs the reception signal from the reception processing unit 26 to the reception data processing unit 14 at the time of data communication. The reception data processing unit 14 recovers reception data from the input reception signal.

In the present embodiment, the ranging signal transmission processing unit 13 is controlled by the control unit 11, and generates a signal for outputting the 2-frequency ranging signal. In the present embodiment, the ranging signal transmission processing unit 13 continuously generates and outputs, for example, a high level ("H") corresponding to a logical value "1" in consideration of transmission in the FSK modulation scheme. In the following description, the succession of "1" or "H" is referred to as "succession 1".

In the ranging, the control unit 11 causes the switch 16 to select the output of the ranging signal transmission processing unit 13, and supplies the output of the reception processing unit 26 to the ranging processing unit 15 through the switch 17. The sequence 1 from the ranging signal transmission processing unit 13 is given to the data generator 21 via the switch 16. The operation of the transceiver circuit 20 is the same as that in data communication even in the case of ranging. When the continuation 1 is input to the data generator 21, the oscillator 22 outputs an oscillation output having a frequency corresponding to the continuation 1.

That is, at the time of ranging, the transmission signal of the oscillator 22 becomes CW which is a non-modulated carrier. For example, when a frequency shift with respect to a logical value "1" is set to 200kHz, CW of a frequency of +200kHz with respect to the center frequency of a predetermined transmission channel is output from the oscillator 22 when consecutive 1 s are input to the transmission circuit 20. The transmission channel of the transmission signal from the oscillator 22 is set by the control unit 11.

However, it is conceivable to generate the 2 nd wave in correspondence with the continuation 1 by a method of generating the 1 st wave in correspondence with the continuation 1. For example, 2 transmission channels are used to generate 2 CWs corresponding to consecutive 1 s.

However, in the distance measurement using 2 waves, the distance that can be measured is { light speed c/(f) }_H-f_L) } × (1/2). In the case of generating 2 CWs using 2 channels, the distance that can be measured is limited by the channel spacing. For example, when the channel interval of the transmission channel is 3MHz, the ranging result is folded back at about 50m, and thus the range that can be measured is about 50 m.

Therefore, in the present embodiment, control is performed so that 2-wave ranging signals are generated in the same channel. That is, the control unit 11 controls the ranging signal transmission processing unit 13 to generate consecutive 1 s and to continuously generate and output a low level ("L") signal corresponding to a logical value "0". In addition, the succession of consecutive "0" or "L" is referred to as "consecutive 0".

When a continuous 0 is input, the data generator 21 outputs an oscillation output having a frequency corresponding to a logical value "0" from the oscillator 22. That is, in this case, the transmission signal from the oscillator 22 is also CW which is an unmodulated carrier. For example, in the case where the frequency shift with respect to the logical value "0" is set to-200 kHz, when consecutive 0 s are input to the transmission circuit 20, CW of a frequency of-200 kHz with respect to the center frequency of the prescribed transmission channel is output from the oscillator 22.

In the present embodiment, control is performed as follows: of the 2 waves of the ranging signal, for example, CW generated in a predetermined channel corresponding to consecutive 1 is used as the 1 st wave, and CW generated in the same channel as the 1 st wave corresponding to consecutive 0 is used as the 2 nd wave.

In the ranging, the control unit 11 causes the switch 16 to select the output of the ranging signal transmission processing unit 13, and supplies the output of the reception processing unit 26 to the ranging processing unit 15 through the switch 17. Consecutive 1 s or consecutive 0 s from the ranging signal transmission processing unit 13 are given to the data generator 21 via the switch 16. The operation of the transceiver circuit 20 is the same as that in data communication even in the case of ranging. The data generator 21 outputs an oscillation output of a frequency corresponding to the consecutive 1 from the oscillator 22 when the consecutive 1 is input, and outputs an oscillation output of a frequency corresponding to the consecutive 0 from the oscillator 22 when the consecutive 0 is input. That is, in the ranging, the transmission signal of the oscillator 22 becomes CW which is a non-modulated carrier, and the difference between the frequencies of the 2-wave transmission signals corresponds to the frequency shift amounts set in correspondence with the logical values "1" and "0".

For example, when a frequency shift with respect to a logical value "1" is set to 200kHz, CW of a frequency of +200kHz with respect to the center frequency of a predetermined transmission channel is output from the oscillator 22 when consecutive 1 s are input to the transmission circuit 20. In the present embodiment, CW in this case is used as the frequency f of the 2 waves of the ranging signal_HOf the signal of (1).

In the present embodiment, the frequency shift with respect to the logical value "0" is set to-200 kHz, and when 0 is continuously input to the receiving/transmitting circuit 20, the oscillator 22 outputs a phase reference signalHaving a frequency f_HThe center frequency of the transmission channel of (2), CW of a frequency of 200 kHz. In the present embodiment, CW in this case is used as the frequency f of the 2 waves of the ranging signal_LOf the signal of (1).

Next, the operation of the embodiment thus configured will be described with reference to fig. 4 and 5. Fig. 4 is an explanatory diagram for explaining frequency components of the ranging signal, and fig. 5 is a flowchart for explaining the operation of the embodiment.

The horizontal axis of fig. 4 indicates frequency, which indicates the transmission band of predetermined N channels (ch) used for data communication, and the upward arrows indicate the center frequencies of the respective channels. In the present embodiment, data communication and ranging are performed using N transport channels shown in fig. 4. The transmission channel in fig. 4 shows an example in which each channel has a frequency band of 3MHz (the channel interval is 3MHz), but the channel interval is not particularly limited.

In the example of fig. 4, the band of a predetermined 1 channel is shown in the lower stage by being enlarged, and an upward broken-line arrow corresponds to the center frequency of the adjacent 2 channels. An example of the oscillator 22 is shown constituted as follows: an oscillating output is generated with a frequency shift of 200kHz corresponding to data "1" and a frequency shift of-200 kHz corresponding to data "0".

In step S1 of fig. 5, the control unit 11 determines whether the ranging mode or the data communication mode is set. For example, the control unit 11 may set the ranging mode and the data communication mode in response to a request from a host computer, not shown. For example, the host may also specify a ranging mode and a data communication mode according to a user operation.

If it is determined that the ranging mode is not set, the control unit 11 performs a process corresponding to the data communication mode (step S2). That is, the control unit 11 controls the transmission data processing unit 12 and the reception data processing unit 14 to perform data communication. The transmission data processing section 12 generates transmission data. The transmission data is supplied to the data generator 21 of the transceiver circuit 20 via the switch 16. The data generator 21 generates data for FSK modulation based on the transmission data to vary the oscillation frequency of the oscillator 22. Thereby, an FSK modulated signal corresponding to the transmission data is generated from the oscillator 22. An FSK modulated signal (transmission signal) from the oscillator 22 is amplified by the power amplifier 23, and then supplied to the antenna 25 via the switch 24 to be transmitted.

The reception signal induced in the antenna 25 is supplied to the reception processing unit 26 via the switch 24. The reception processing unit 26 performs FSK demodulation on the received signal to obtain a demodulated signal. In the data communication mode, the demodulated signal is supplied to the reception data processing unit 14 via the switch 17. The reception data is recovered from the inputted reception signal by the reception data processing unit 14. In this manner, data is transmitted and received in the data communication mode.

If it is determined that the distance measurement mode is set, the controller 11 proceeds to step S3 from step S1. For example, when the user wants to obtain the distance between the terminal including the distance measuring device of fig. 1 and the other device, the user designates the distance measuring mode. When the ranging mode is designated, the control unit 11 determines whether or not the 1 st wave transmission timing is reached in step S3, determines whether or not the 2 nd wave transmission timing is reached in step S6 if the determination is no, and determines whether or not the reception timing is reached in step S9 if the determination is no.

For example, the control unit 11 may perform control so that the ranging mode is executed in a predetermined packet in data communication to transmit and receive a ranging signal. If the transmission timing of the 1 st wave is detected in step S3, the control unit 11 generates consecutive 1S in the ranging signal transmission processing unit 13 (step S4).

The continuation 1 from the ranging signal transmission processing section 13 is supplied to the data generator 21 via the switch 16. The data generator 21 generates an oscillation output corresponding to continuous 1, that is, CW, which is an unmodulated carrier wave having an oscillation frequency of +200kHz which is the center frequency of the channel, as a 1 st wave output from the oscillator 22 (step S5). For example, the data generator 21 generates a ranging signal CW1 of the center frequency +200kHz of the nth channel (ch) of fig. 4 as the 1 st wave from the oscillator 22. The 1 st wave is amplified by the power amplifier 23, supplied to the antenna 25 via the switch 24, and transmitted.

Next, when it is determined in step S3 that the timing is not the 1 st wave transmission timing, the controller 11 determines in step S6 whether or not the timing is the 2 nd wave transmission timing. The control unit 11 transmits the 2 nd wave of the ranging signal if it is determined that the 2 nd wave transmission timing is reached.

In the present embodiment, the control unit 11 causes the ranging signal transmission processing unit 13 to generate consecutive 0S in order to generate the 2 nd-wave ranging signal in the same channel as the 1 st wave (step S7). The consecutive 0 s from the ranging signal transmission processing section 13 are supplied to the data generator 21 via the switch 16. The data generator 21 generates, as a 2 nd wave output, CW which is an unmodulated carrier wave having an oscillation frequency of-200 kHz from the center frequency of the channel including the 1 st wave, which is an oscillation output corresponding to the continuous 0, from the oscillator 22 (step S5). For example, in the case where the 1 st wave is the ranging signal CW1 of fig. 4, the data generator 21 generates the ranging signal CW2 of the center frequency of the n-th channel (ch) -200kHz as the 2 nd wave from the oscillator 22. The 2 nd wave is amplified by the power amplifier 23, supplied to the antenna 25 via the switch 24, and transmitted.

In this manner, the transceiver circuit 20 outputs 2-wave ranging signals in the same channel. In the example of fig. 4, the frequency interval between these ranging signals CW1 and CW2 is 400 kHz. Therefore, in this case, the distance measurement result is folded back at about 375m, and thus the distance that can be measured can be extended to about 375 m. When 2-wave ranging signals are CW1 and CW3 of adjacent channels, the range that can be measured is only about 50m as described above.

If it is determined in step S6 that the timing is not the 2 nd wave transmission timing, the controller 11 determines whether or not the timing is the reception timing in step S9. If it is determined that the reception timing is reached, the control unit 11 controls the switch 24 to supply the reception signal induced in the antenna 25 to the reception processing unit 26, and obtains a demodulated signal by FSK demodulation. The distance measurement processing unit 15 takes in the demodulated signal via the switch 17 and detects the phase. The distance measurement processing unit 15 performs distance measurement calculation for obtaining the distance between the own device and the other device using the detection result of the phase.

In addition, in the case of the method of the prior art document, the local device or another device needs to transmit the detection result of the phase to the other device. The control unit 11 may transmit the phase information to the partner apparatus by data communication using the transmission data processing unit 12, for example. Alternatively, the control unit 11 may receive the phase information from the partner apparatus by data communication.

As described above, in the present embodiment, the transmitter/receiver circuit can be shared between the circuit portion for data communication using FSK modulation and the circuit portion for distance measurement, and an increase in the circuit scale can be suppressed. In the present embodiment, a plurality of CWs in a frequency band within 1 channel of a transmission channel used for data communication are used as a ranging signal, and ranging over a relatively long distance can be performed.

In the present embodiment, CW that generates 2 waves in 1 transmission channel can increase the number of CWs that can be used for the ranging signal, and can improve the ranging accuracy, compared to the case where only 1 CW is generated in 1 transmission channel using only consecutive 1.

Although fig. 1 shows a device including both a transmitting device and a receiving device in distance measurement and data communication, the transmitting device and the receiving device may be configured separately, and the distance measurement transmitting device may be configured by the control unit 11, the transmission data processing unit 12, the distance measurement signal transmission processing unit 13, the switch 16, the data generator 21, the oscillator 22, the power amplifier 23, and the antenna 25 in fig. 1. Similarly, the distance measurement receiving apparatus can be configured by the control unit 11, the reception data processing unit 14, the distance measurement processing unit 15, the switch 17, the reception processing unit 26, and the antenna 25 in fig. 1.

Not only the control unit 11, but also the transmission data processing unit 12, the distance measurement signal transmission processing unit 13, the reception data processing unit 14, and the distance measurement processing unit 15 may be configured by a processor using a CPU, an FPGA, or the like, may be operated according to a program stored in a memory not shown to control each unit, or may be implemented by a hardware electronic circuit as a part or all of the functions.

(modification example)

In the above embodiment, the example in which the 2-wave ranging signal is generated in 1 transmission channel was described, but the 2-wave ranging signal may be generated in a different transmission channel. For example, CW3 in the (n-1) channel and CW2 in the n channel in fig. 4 may be used as the 2-wave ranging signals.

In this case, the distance that can be measured can be extended by a little.

(modification example)

Fig. 6 is an explanatory diagram for explaining a modification. In fig. 6, the horizontal axis represents distance and the vertical axis represents phase, and 2 measurement results are shown.

Since the detection phase difference exceeding 2 pi cannot be detected, a return occurs in the distance measurement result, and there are a plurality of distance candidates for the calculated detection phase difference. In the above embodiment, 2-wave CW (ranging signal) in the same channel is generated, and the distance of the return can be increased. However, it is considered that the ranging accuracy of the ranging result using the CW of 2 waves in the same channel is low. Therefore, in the present modification, the CW of 2 waves in the same channel is used only for the correction of the folding back, and the ranging result is obtained using another CW group.

In fig. 6, the results of ranging by a group of 2-wave CWs (hereinafter referred to as a group of ranging CWs) other than a group of 2-wave CWs (hereinafter referred to as a group of folding-back CWs) in the same channel are shown by solid lines. The group of the ranging CWs selects a transmission channel so that the frequency difference of 2 CWs becomes relatively large. Therefore, in the ranging using the group of CWs for ranging, the distance to be folded back is relatively short, but the ranging accuracy is relatively high.

In FIG. 6, the left side of the above expression (7) is represented by θ_detAnd represents the distances R and theta_detThe relationship between them. The solid line in fig. 6 is an example of a group using a CW for ranging, and the broken line is an example of a group using a CW for foldback correction. In addition, the sum θ of the detected phase differences calculated in the above expression (7) is used_detIt is also possible to take values other than-pi (rad) and pi (rad), but the sum of the detected phase differences θ shown in FIG. 6_detTo between-pi (rad) and pi (rad). This is because, in general, the range [ - π (rad), π (rad)]Internal display phaseAnd (4) an angle.

As shown by the solid line in fig. 6, it is understood that the sum θ of the detected phase difference and the group using the CW for ranging_detThe distance change with respect to the change of (2) is small, and therefore high distance measurement accuracy can be obtained. If a group using a CW for ranging is assumed, the sum of detected phase differences θ can be obtained_det0In this case, as shown in fig. 6, R exists as a distance candidate of the distance measurement result₁、R₂、R₃。

On the other hand, the broken line in fig. 6 indicates the relationship between the sum of the detected phase differences obtained using the set of the folding correction CWs and the distance. The broken line in fig. 6 indicates that the folding distance is relatively long. In order to select an accurate distance from among R1, R2, and R3 as a distance measurement result, a distance in the vicinity of a distance obtained by adding the detected phase differences obtained from the group using the folding correcting CW may be selected among these distances. For example, θ is detected in the group using the CW for the fold correction_det1In the case of (3), the distance R obtained using the group of CW for distance measurement can be used₂And judging the result as a correct ranging result. In this way, the group of CWs of 2 waves in the same channel is used for correction of the return of the ranging result.

Fig. 6 shows an example in which only 1 set is used as a set of CWs for ranging, but a plurality of sets may be used. As the group of CWs for ranging, a CW of a predetermined channel corresponding to consecutive 1 and a CW of another channel corresponding to consecutive 0 may be used, or a CW of mutually different channels corresponding to consecutive 1 or consecutive 0 may be used.

Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the scope equivalent thereto.