Generalized Logic Circuitry for the Control of Coherent Detection Applied to the Measurement of Ultrasonic Pulse-Echo Attenuation

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Abstract
Coherent signal detection techniques are applied to conventional ultrasonic pulse-echo measuring apparatus to achieve a 20–25 dB improvement in the minimum useful signal. Logic circuitry is described which generates all the reference and trigger waveforms required by the sampling oscilloscope, lock-in amplifier, and other equipment. No other pulse generators are required. Amplitude adjustment of the pulsed rf comparator is determined to be equal that of the echo by a null indication of the lock-in voltmeter.

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