Signal synthesizer

摘要

A signal synthesizer is provided for producing pulses simulating characteristics of echo pulses generated during ultrasonic scanning so that the simulated pulses can be used in the calibration of equipment for processing the outputs of ultrasonic transducers. The synthesizer produces an envelope signal of selectively variable amplitude and rise and fall time and multiplies this envelope respectively with a high frequency pulse train and a substantially zero amplitude signal in a dual matched multiplier so that the subtractively combined outputs of the multiplier are free of unwanted feedthrough components introduced by the mulitplier.