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:
May. 02, 1978
Filed:
Mar. 29, 1977
Yoshiro Sugai, Kawagoe, JA;
Pioneer Electronic Corporation, Tokyo, JA;
Abstract
A noise limiting circuit for an FM stereo receiver comprises a filter circuit 13 for grounding high frequency components in the detector output signal through a transistor switch 14 in response to a low field strength signal supplied by the IF amplifier. The filter circuit, when activated, also grounds the 19 KHz pilot signal to automatically switch from a stereo to monaural mode, which further improves the S/N ratio. The pilot signal grounding effect may be enhanced by including an inductor in the filter circuit which, in combination with the filter capacitor, is tuned to the pilot signal frequency. The transistor 14 is switched in a rapid on -- slow off mode by providing a storage capacitor 20 and discharge resistors 17, 19 in the base control circuit of the transistor, and the filter switching or squelch level may be adjusted by a variable resistor 22.