Automatic threshold squelch
First Claim
1. An automatic threshold squelch circuit, for radio receiver having a demodulator responsive to noise signals from the receiver demodulator for generating a mute signal when no transmission is being received by the receiver, said squelch circuit comprising:
- noise detector means for producing a unidirectional signal level as a function of the noise signal from the demodulator;
memory means, coupled to the noise detector means, for sampling and storing the unidirectional signal level when no transmissions are being received by the receiver;
comparator means, coupled to the detector means and the memory means, for comparing the unidirectional signal level from the noise detector means to the stored signal level, and generating an unmute signal when the uni-directional signal level is less than the store signal level.
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Accused Products
Abstract
An automatic threshold squelch circuit, responsive to noise signals from the receiver demodulator, having automatic means for setting the squelch level. A noise detector is coupled to the demodulator and to a comparator and sample and hold circuit such that a predetermined portion of the detected noise signal level is stored in the sample and hold circuit when no signal is being received. The stored noise level is then compared to the detected noise signal from the noise detector and a mute signal is generated in response to the detected noise level exceeding the stored signal level.
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Citations
13 Claims
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1. An automatic threshold squelch circuit, for radio receiver having a demodulator responsive to noise signals from the receiver demodulator for generating a mute signal when no transmission is being received by the receiver, said squelch circuit comprising:
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noise detector means for producing a unidirectional signal level as a function of the noise signal from the demodulator; memory means, coupled to the noise detector means, for sampling and storing the unidirectional signal level when no transmissions are being received by the receiver; comparator means, coupled to the detector means and the memory means, for comparing the unidirectional signal level from the noise detector means to the stored signal level, and generating an unmute signal when the uni-directional signal level is less than the store signal level. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Communications receiving apparatus which operates in response to incoming signals, comprising:
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radio receiver apparatus including RF, mixer, IF, demodulator, and audio sections; noise detector means for producing a unidirectional signal level in response to noise signals from the receiver demodulator; memory means having an input coupled to the noise detector means, for storing the unidirectional signal of the highest level applied to the memory means input; comparator means, coupled to the detector means and the memory means, for comparing the unidirectional signal level from the noise detector means to the stored signal level and for generating an unmute signal when the uni-directional signal level is less than the stored signal level. - View Dependent Claims (8, 9, 10)
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11. In communications receiving apparatus having a demodulator, a method of providing automatic squelch, comprising the steps of:
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(a) producing a unidirectional signal level as a function of a noise signal level from the receiver demodulator; (b) storing the unidirectional signal level in response to a predetermined condition producing a stored signal level; (c) comparing the unidirectional signal level to the stored signal level and generating a squelch control signal when the unidirectional signal level is less than the stored signal level. - View Dependent Claims (12, 13)
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Specification