Abstract: There is disclosed a liquid velocity measuring apparatus comprising an actuable generator for providing a relatively high frequency signal to a transmitting transducer for directing an ultrasonic wave into a conduit through which liquid is directed. A receiver transducer is disposed to receive the acoustical wave as reflected from the liquid, and to provide an output signal to be amplified and demodulated to provide a train of high frequency pulses, the frequency of which is indicative of the velocity of the liquid directed through the conduit. The train of pulses is applied to a counter and a decoder for respectivey counting and decoding the pulses to provide a signal to a display whereby a digital indication of the liquid velocity is given.

Abstract: A liquid velocity measuring system is described utilizing ultrasonic waves to measure the velocity of a liquid and in particular, the velocity of blood as directed through a conduit external of the patient's body. The liquid velocity measuring system comprises an ultrasonic soundwave transmitting transducer energized by a continuous wave generator, preferably at a frequency of 3.13 MHz. The transmitting transducer is disposed with respect to the conduit such that the transmitted ultrasonic waves are backscattered or reflected from ultrasonic reflection centers in the blood. This signal is received and detected by a second ultrasonic transducer. The reflected ultrasonic wave is frequency-shifted dependent upon the velocity of the liquid directed through the conduit and is detected by the second transducer to be amplified and demodulated subsequently, before being applied to a microbubble detection circuit in accordance with the teachings of this invention.