The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 15, 1988
Filed:
Sep. 30, 1986
Kenneth G Voyce, Bellevue, WA (US);
The Boeing Company, Seattle, WA (US);
Abstract
A squelch trigger circuit for use in an RF receiver for receiving a modulated carrier signal having a predetermined information band, and producing a squelch trigger signal. The squelch trigger circuit includes a bandpass filter connected to receive the modulated carrier signal and having a passband that includes the information band. The output of the bandpass filter is connected to an AGC circuit that includes a detector for producing a detection signal indicative of the level of the AGC output signal. The detection signal is input to a high pass filter having a corner frequency selected such that the noise signal includes only frequency components higher than one-half of the passband of the bandpass filter, such that the noise signal produced by the high pass filter corresponds to the out of band noise components of the AGC output signal. The noise signal is input to a noise detector for producing a noise level signal, and the noise level signal is compared to a threshold to produce the squelch trigger signal. The threshold may be temperature compensated to model thermal noise in the AGC circuit.