Patent ID: 9157984
Filing Date: 2015-10-13
Classification: G01S,G06F

Abstract:
1. A position detection system, comprising: at least one moving body including a transmission device which simultaneously sends out a trigger signal indicative of transmission timing and an ultrasonic signal obtained by modulating a signal of a frequency as a reference by pseudo random sequence data having high self-correlativity; and a reception device which receives said trigger signal and said ultrasonic signal to detect a position of said moving body, wherein said reception device comprises at least two ultrasonic reception units provided at a predetermined interval which receive said ultrasonic signal, a unit which calculates a correlation value between a waveform of said ultrasonic signal and a model waveform of said pseudo random sequence determined in advance according to said moving body, after respectively filtering said waveform of said ultrasonic signal and said model waveform by a same band filter that remains an intrinsic band of each of said at least one moving body, a unit which subjects the waveform of said ultrasonic signal and the model waveform of said pseudo random sequence determined in advance according to said moving body to filtering to calculate a correlation value between the two waveforms, a unit which detects a first peak of any said correlation value calculated and calculates a time of propagation of each ultrasonic to arrive at each of said two ultrasonic reception units from a time point of reception of said trigger signal and a time point of detection of the correlation peak, and a unit which calculates a position of said moving body based on said ultrasonic propagation time calculated and the interval length between said ultrasonic reception units, and wherein as said pseudo random sequence, a different sequence whose cross-correlativity is low is used.