Universal doppler flowmeter tester

摘要

A circuit simulating the electrical signal response of a flowing liquid whose velocity is to be measured by a Doppler flowmeter. The circuit takes the electrical flowmeter transmit signal from a Doppler flowmeter and modifies its frequency to derive a simulated Doppler shifted signal. The latter signal is used to modulate the transmit signal in a double side band, balanced modulator which suppresses the frequency of the transmit signal and produces upper and lower side band frequencies mimicking a Doppler shifted return signal. The latter signal is fed to the signal receiving transducer of a Doppler flowmeter for test purposes.