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:
Apr. 25, 1995
Filed:
Sep. 03, 1992
Ryoichi Yokoyama, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An FM noise reduction circuit including a level detection circuit receiving an intermediate frequency signal. The level detection circuit rectifies the intermediate frequency signal, and outputs a rectified intermediate frequency signal. A first frequency filter passes the rectified intermediate frequency signal in a first frequency range, and outputs a first voltage responsive to the portion of the rectified intermediate frequency signal passed in the first frequency range. A first interference signal detection circuit includes a second frequency filter. The second frequency filter passes the rectified intermediate frequency signal in a second frequency range and outputs a second voltage responsive to the portion of the rectified intermediate frequency signal passed in the second frequency range. The second interference signal detection circuit includes a third frequency filter. The third frequency filter passing the rectified intermediate frequency signal in a third frequency range, and outputs a third voltage responsive to the portion of the rectified intermediate frequency signal passed in the third frequency range. The first, second, and third frequency ranges are different. A control circuit controls muting, high frequency components, and blending of a demodulated audio output responsive to the first, second, and third voltages, to reduce FM noise.