METHOD FOR DELAY MEASUREMENT FOR AN ULTRASONIC SIGNAL IN A FLOWING FLUID

The present invention relates to a method for ultrasonic delay measurement in a fluid, in which a fluid flowing through a measurement path is subjected to a first transmission signal, generated by an ultrasonic transducer, at a first frequency f1 and to a second transmission signal, generated by the ultrasonic transducer, at a second frequency f2, the first and second transmission signals are received by an ultrasonic transducer and first and second received signals each having multiple waves are generated, the delay difference is determined from the received signals, a phase difference (PD) between the first received signal at the first frequency f1 and the second received signal at the second frequency f2 is measured, and the position of a measurement point in the region of the waves (wave train) of the received signal is derived from the measured phase difference (PD).