Method and circuit for indirectly measuring ultrasonic transmission time

The invention discloses a method and a circuit for indirectly measuring ultrasonic transmission time. The method for indirectly measuring the ultrasonic transmission time is based on a reference signal. The measurement of the non-full-period flight time of the forward and reverse flow relative reference signals is converted into the measurement of the pulse width; the time measurement precision isimproved by adopting measurement of a certain number of continuous pulse widths, a pulse width modulation and phase shift circuit is designed in order to solve the influence of signal period deviation on flight time measurement, and measurement errors are reduced by designing a correction circuit. 本发明公开了一种间接测量超声波传输时间的方法及电路。本发明的间接测量超声波传输时间的方法基于参考信号，将顺、逆流相对参考信号的非整周期飞行时间的测量转换为脉冲宽度的测量，通过采用一定数量连续脉冲宽度的测量提高时间测量的精度，为解决信号周期偏差对飞行时间测量的影响，设计了脉宽调制和移相电路，并通过校正电路的设计，减小测量误差。