Patent ID: 11899097
Assignee: TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 8:
9. The distance measurement device according to claim 1, wherein
the first transmitter-receiver samples the second phase information for one period of the second demodulated signal or longer,
the second transmitter-receiver performs, twice or more, sampling of the first phase information for one period of the first demodulated signal or longer,
when k is a natural number, the calculation unit obtains, for each of the second demodulated signal and the first demodulated signal, two samples, phase change of which is maximized through subtraction of a temporally previous sample of a sample, and sets a reference sample to be a temporally later sample among the two samples, phase change of which is maximized, and
for three samples of the reference sample and two samples temporally k samples before and k samples after the reference sample, the calculation unit
calculates, by using the three samples of the first demodulated signal for a first time, an elapsed time tb1 of the second device from a time point at which the reception of the first demodulated signal is started, to a time point at which the first demodulated signal is sampled is obtained,
calculates, by using the three samples of the second demodulated signal, an elapsed time ta1 of the first device from a time point at which the reception of the second demodulated signal is started, to a time point at which the second demodulated signal is sampled is obtained,
calculates, by using the three samples of the first demodulated signal for a second time, an elapsed time tb2 of the second device from a time point at which the reception of the first demodulated signal is started, to a time point at which the first demodulated signal is sampled is obtained,
calculates a first flight time tx,err1 including error by

tx,err1=(TS−ta1−tb1)/2

where TS represents the first or second sampling period,
calculates a second flight time tx,err2 including error by

tx,err2=(TS−ta1−tb2)/2

calculates an average flight time by averaging the first flight time tx,err1 and the second flight time tx,err2, and
calculates the distance based on the average flight time.