Circuit arrangement for determining physical parameters of flowing media by the ultrasonic method

Abstract From the Canadian patent

The invention relates to a circuit for determining the arrival time of an ultrasonic signal. The circuit includes a differentiator for transforming an ultrasonic signal to a substantially linearly increasing signal and a threshold value, detector for transforming the linearly increasing signal to an arrival delay signal. A phase detector in the form of a D-type flip-flop determines the phase position of the arrival delay signal relative to a reference signal. The phase detector generates early signals on early arrival of the delay signal and late signals on late arrival of the delay signal. A regulator integrator is provided between the phase detector and the differentiator for producing an …