Patent ID: 8459119

Claim:
A position detection system, comprising: at least one mobile body including a transmission device which simultaneously transmits a trigger signal indicative of transmission timing and an ultrasonic signal modulated by pseudo random-sequence data having high self-correlativity in each fixed transmission cycle, and a reception device which receives said trigger signal and said ultrasonic signal to detect a position of said mobile body, wherein said reception device comprises: an ultrasonic reception unit which receives said ultrasonic signal, and a data processing unit which generates an ultrasonic model waveform of a pseudo random-sequence of said ultrasonic signal, calculates a correlation value between a waveform of a received ultrasonic signal and said ultrasonic model waveform generated, detects a first peak of the calculated correlation value and calculates an ultrasonic propagation time from a time point of reception of said trigger signal and a time point of detection of the correlation peak, as well as determining a position of said mobile body based on said ultrasonic propagation time calculated, wherein said transmission device transmits said ultrasonic signal, and an electromagnetic wave signal including said trigger signal and data which defines said pseudo random-sequence in each fixed transmission cycle, and wherein said pseudo random-sequence is an M-sequence and data defining said pseudo random-sequence which said electromagnetic wave signal includes is M-sequence initial condition data.