Ranging device, ranging method, and recording medium

1. A ranging device including transducers, the ranging device comprising:

a transmission circuit configured to cause at least one of the transducers to transmit a transmission wave;

a reception circuit configured to output a received signal obtained by digitizing a reflected wave of the transmission wave by using a sampling frequency equal to or more than a frequency of the transmission wave, the reflected wave being received by each of the transducers;

a transfer data generation circuit configured to

separate, into a target period and a non-target period, time-series received signals output from the reception circuit, the target period being a period in which a wave height is equal to or more than a threshold, the non-target period being a period in which a wave height is less than the threshold,

perform thinning-out processing on received signals in the non-target period, and

generate waveform information indicating a waveform received by the transducer; and

a transfer circuit configured to output the waveform information generated by the transfer data generation circuit.

2. The ranging device according to claim 1 , wherein

the transfer data generation circuit is configured to specify the target period from a waveform of the time-series received signals output from the reception circuit.

3. The ranging device according to claim 1 , wherein

the transfer data generation circuit is configured to specify, as the target period, a period in which the wave height is equal to or more than the threshold and predetermined periods before and after the period, the target period being specified from the time-series received signals output from the reception circuit.

4. The ranging device according to claim 1 , wherein

the waveform information includes one or more of a start time of the target period, an end time of the target period, and a sampling cycle of the target period.

5. The ranging device according to claim 1 , wherein

the transfer data generation circuit is configured to

clock a time elapsed from when the transmission wave is transmitted, and

change processing of generating the waveform information in accordance with a value of the clocked time.

6. The ranging device according to claim 1 , wherein

the transfer data generation circuit is configured to

clock a time elapsed from when the transmission wave is transmitted, and

specify the target period in accordance with a value of the clocked time.

7. The ranging device according to claim 5 , wherein

the transfer data generation circuit is configured to

clock a time elapsed from when the transmission wave is transmitted, and

change, in accordance with a value of the clocked time, one or both of the number of bits of a wave height value and a temporal resolution.

8. The ranging device according to claim 1 , wherein

the transfer data generation circuit is configured to

clock a time elapsed from when the transmission wave is transmitted, and

specify, as the target period, a period other than a period from a start of the time clocking until a stop of reverberation generated in the transducer having transmitted the transmission wave.

9. The ranging device according to claim 8 , wherein

the waveform information generated by the transfer data generation circuit includes information on a transmission signal.

10. The ranging device according to claim 1 , further comprising a signal processing circuit configured to

perform envelope detection processing on the received signal output from the reception circuit, and

generate an envelope signal being a processing result of the envelope detection processing.

11. The ranging device according to claim 1 , further comprising a signal processing circuit configured to

perform logarithmic transformation processing on the received signal output from the reception circuit after envelope detection processing, and

generate an envelope signal being a processing result of the logarithmic transformation processing.

12. The ranging device according to claim 10 , wherein

the transfer data generation circuit is configured to specify, as the target period, a period in which a wave height of the envelope signal is equal to or more than the threshold and predetermined periods before and after the period.

13. The ranging device according to claim 12 , wherein

the transfer data generation circuit is configured to output the envelope signal generated by the signal processing circuit.

14. The ranging device according to claim 10 , wherein

the transfer data generation circuit is configured, in a period during which the received signal or the envelope signal is in a saturated state, to output, as the waveform information, information indicating the saturated state and a start time and an end time of the period.

15. The ranging device according to claim 1 , further comprising a signal processing circuit configured to

perform quadrature detection processing on the received signal output from the reception circuit, and

generate an I value and a Q value being a processing result of the quadrature detection processing.

16. The ranging device according to claim 15 , wherein

the transfer data generation circuit is configured to specify, as the target period, a period in which wave heights of the I value and the Q value are equal to or more than the threshold.

17. The ranging device according to claim 15 , wherein

the transfer data generation circuit is configured to output the I value and the Q value generated by the signal processing circuit.

18. A ranging method performed by a ranging device including transducers, the ranging method comprising:

causing at least one of the transducers to transmit a transmission wave;

outputting a received signal obtained by digitizing a reflected wave of the transmission wave by using a sampling frequency equal to or more than a frequency of the transmission wave, the reflected wave being received by each of the transducers;

separating, into a target period and a non-target period, time-series received signals output by the outputting, the target period being a period in which a wave height is equal to or more than a threshold, the non-target period being a period in which a wave height is less than the threshold;

performing thinning-out processing on received signals in the non-target period;

generating waveform information indicating a waveform received by the transducer; and

outputting the waveform information generated by the generating.

19. A non-transitory computer-readable recording medium on which programmed instructions are recorded, the instructions being executable by a computer serving to control a ranging device including transducers, the instructions causing the computer to:

cause at least one of the transducers to transmit a transmission wave;

output a received signal obtained by digitizing a reflected wave of the transmission wave by using a sampling frequency equal to or more than a frequency of the transmission wave, the reflected wave being received by each of the transducers;

separate, into a target period and a non-target period, time-series received signals, the target period being a period in which a wave height is equal to or more than a threshold, the non-target period being a period in which a wave height is less than the threshold;

perform thinning-out processing on received signals in the non-target period;

generate waveform information indicating a waveform received by the transducer; and

output the waveform information.