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:
Jun. 25, 1991
Filed:
Dec. 22, 1989
Oliver L Richards, Jr, N. Grosvenor Dale, CT (US);
Thomas L Field, Rutland, MA (US);
Allegro Microsystems, Inc., Worcester, MA (US);
Abstract
An FM stereo decoding and separating circuit has an (AM) demodulator multiplier to which is connected the FM stereo composite signal and a signal of dominant frequency equal to and in phase (0.degree.) with respect to the pilot signal for retrieving the L-R signal from the composite signal. This demodulator also has a blend control circuit for diminishing the magnitude of the L-R signal as a function of a blend control voltage that may be applied to the input of the blend control circuit. The decoding circuit also includes a special multiplier to which is connected the FM stereo composite signal and a signal of dominant frequency equal to that of the 38 KHz subcarrier but shifted 90.degree. with respect to the phase of the pilot, for AM demodulating the composite signal with respect to the subcarrier, and a low pass filter connected to the special mixer output for producing an output containing only demodulated noise originally appearing about the pilot in the composite signal, and a rectifier connected to the filter output and to the blend-control input for effecting blending to a degree directly related to the amount of noise in a narrow band about the pilot in the composite signal.