USA As Represented by Secretary of the Navy

Harry M Crain

Lynn A Poole

A combined analog and digital ratio detector circuit produces a gated out whenever the average amplitude of an information pulse exceeds a fixed preset threshold in the presence of an interfering noise background. The circuit also has the capability of tracking the average value of the noise to null it out, thereby maintaining the preset signal-to-threshold ratio over a wide range of slowly varying noise amplitudes. The circuit's functional breakdown is as follows: (1) an input operational amplifier has a time constant related to the information pulse duration; (2) a noise voltage tracking and nulling loop has a time constant related to the background noise characteristics; (3) a logic interface between a system clock and a counter (part of item 2) prevents 'racing'; and (4) an adjustable threshold gate sets the false alarm rate at an acceptable information retrieval probability.

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State College, PA, United States of America

Harry M Crain