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:
Jan. 13, 1987
Filed:
Jul. 02, 1985
Richard A Kennedy, Russiaville, IN (US);
Fredrick A Aldridge, Russiaville, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A noise blanking signal generator for an AM radio receiver includes a product detector adapted to receive an IF signal modulated by an AF signal and synchronously detect the AF signal, a first low pass filter adapted to derive from the product detector a filtered voltage indicating the average IF signal strength, a second low pass filter adapted to derive from the product detector an AF signal voltage and a reference voltage generating circuit ratiometrically related to the product detector through a common DC power supply and effective to generate a reference voltage substantially equal to the filtered voltage in the absence of an IF signal. A voltage divider comprising a pair of resistors connected in series across the outputs of the first and second low pass filters has an output at the junction of the resistors, the resistors being of such ratio as to generate, when the AF signal equals a predetermined modulation level with reference to the IF signal strength, a voltage equal to the reference voltage at the voltage divider output, a comparator effective to compare the voltage at the output of the voltage divider with the reference voltage and generate a noise blanking signal when the former exceeds the latter and offset means effective to bias the comparator do not generate the noise blanking signal when the voltage at the output of the voltage generator does not exceed the reference voltage.