POSITION DETERMINATION SYSTEM, TRANSMITTING DEVICE, RECEIVING DEVICE, AND POSITION DETERMINATION METHOD

摘要

The positions of a plurality of transmitting devices are precisely detected by using a direct wave that first arrives at a receiving device, without being affected by other ultrasonic signals from the transmitting devices. A position determination system comprises: a movable body including a transmitting device for simultaneously transmitting a trigger signal and an ultrasonic signal modulated based on pseudo-random sequence data having a high autocorrelation; and a reception processing device for detecting the position of the movable body. The reception processing device includes: at least two ultrasonic wave receiving means for receiving an ultrasonic signal; a means for calculating a correlation value between the received waveform of the ultrasonic signal and a modulation reference waveform of a pseudo-random sequence predetermined according to the movable body; a means for calculating, from a time point when the trigger signal is received and another time point when the first peak value of the correlation value is detected, an ultrasonic wave transmission time for the ultrasonic wave to reach the two ultrasonic wave receiving means; and a means for calculating the position of the movable body based on the ultrasonic wave transmission time and the distance length between the two ultrasonic wave receiving means. A different sequence having a low cross-correlation is used as the pseudo-random sequence.