Patent ID: 8427905
Filing Date: 2013-04-23
Classification: G01S

Abstract:
1. An optimum pseudo random sequence determining method of a reception device for detecting a position of a transmission device by receiving an ultrasonic signal transmitted from said transmission device, comprising the steps: a) sending, from said transmission device, an ultrasonic signal modulated by data of a pseudo random sequence generated based on data which defines a pseudo random sequence having high self-correlativity; b) receiving the ultrasonic signal at said reception device, generating an ultrasonic model waveform of a pseudo random sequence of said ultrasonic signal and executing processing of correlation between the ultrasonic model waveform and the received ultrasonic signal to detect a correlation waveform; and c) at said reception device, with respect to data of different pseudo random sequences, repeatedly executing said Steps (a) and (b), detecting said correlation waveform in plural, detecting a smallest secondary peak among secondary peaks appearing in each correlation waveform when said ultrasonic model waveform and the received ultrasonic signal coincide in part and determining data of a pseudo random sequence corresponding to the smallest secondary peak as data of an optimum pseudo random sequence for assigning to said transmission device.