Patent ID: 8726733
Filing Date: 2014-05-20
Classification: G01S

Abstract:
1. An ultrasonic measuring method that uses a coded spread spectrum ultrasonic signal, which has a predetermined carrier frequency and which has been modulated with codes that have a coding period synchronized with the carrier frequency, to estimate at least one of the propagation distance and propagation orientation of the coded spread spectrum ultrasonic signal, the method comprising the steps of: (A) receiving the coded spread spectrum ultrasonic signal in at least two receivers, and generating at least two received signals; (B) performing an quadrature detection on the at least two received signals using the carrier frequency, and producing I and Q components of the received signals; (C) performing phase difference processing on the I and Q components of the received signals with a coding period that is synchronized with the period of the carrier frequency, and obtaining I′ and Q′ components from which a phase shift caused by a Doppler shift has been canceled; (D) despreading the I′ and Q′ components of the received signals using different codes from the codes at time intervals that are synchronized with the carrier frequency, and obtaining despread I″ and Q″ components; (E) obtaining information about the amplitudes and phases of the respective received signals by carrying out computations on the I″ and Q″ components of the received signals; and (F) calculating at least one of the propagation distance and propagation orientation of the ultrasonic wave based on the information about the amplitudes and phases that has been obtained from the respective received signals.