Time dependant, variable amplitude threshold output circuit for frequency variant and frequency invariant signal discrimination

Abstract From the Canadian patent

A voice signal compression system wherein the compression threshold may be adjusted to a calibrated level. The system includes a variable gain amplifier for amplifying a voice input signal based on the application of a variable control voltage. A driver increases the power gain of the amplified input signal to provide a power-boosted output signal. In addition to applying the power-boosted output signal to an acoustic output transducer, the power-boosted output is also applied both to a peak detecting comparator and to a threshold reset timer. The comparator produces a digital output that triggers an attack/decay timing generator which produces the control voltage for the variable gain …