Measurement of the ultrasonic velocity in bubble-containing liquids and suspensions

The application of ultrasonic methods to the continuous measurement of mate rial properties for the process control of liquid systems often raises prob lems if the sound propagation is disturbed by gas bubbles. A new measuring method is presented which enables the measurement of the sound velocity in bubble-containing liquids and suspensions with improved accuracy and reliab ility. This method comprises the measurement of the phase shift between a c ontinuous reference signal and a burst-like received signal at two differen t sound frequencies. By using a second frequency, it will also be possible to measure phase shifts greater than one signal period.