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US 4,359,780 AGranted
High speed squelch circuit
AssigneeMotorola, Inc. (Corporate Offices)
InventorCharles M. Day
Life of this patent
Estimating the term…
Abstract
A high frequency squelch circuit for communications receivers with relatively long time delay when operating on weak signals with a short time delay on strong signals which completely eliminates any audible noise burst, and with continuously variable delay as an inverse function of signal strength at intermediate signal levels. The high speed squelch performance is achieved without degrading chatter performance by operating at frequencies above the audio range and utilizing wider noise bandwidth.
Claims8
A communications receiver squelch circuit operable in response to detected noise voltage comprising:
- (a) filter means, adapted to receive the detected noise voltage and being responsive to high frequency noise, for filtering the detected noise voltage to develop a filtered noise voltage;
- (b) comparator means, having an input and an output for comparing the filtered noise voltage to a reference voltage and for generating a control signal at the output when said filtered noise voltage exceeds said reference voltage;
- (c) variable shunt means, having an input and an output coupled to the comparator means output, for generating a voltage inversely dependent upon a signal coupled to the input;
- (d) capacitor means, for coupling the output of the variable shunt means to the output of the comparator means;
- (e) integrator means, coupled to the comparator means input, for integrating filtered noise voltage and coupling the integrated noise voltage to the shunt means input.
2 more elements
Dependencies are inferred from the claim text.