| 摘要 |
An ultrasonic measuring method includes: (A) receiving a coded spread spectrum ultrasonic signal in at least two receivers, and generating at least two received signals; (B) performing an quadrature detection on the 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 with a coding period synchronized with that 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 signals using different codes at time intervals synchronized with the carrier frequency, and obtaining despread I″ and Q″ components; (E) computing the amplitude and phase information based on the I″ and Q″ components; and (F) calculating the propagation distance and/or orientation of the ultrasonic wave based on the amplitude and phase information. |
