Brian L Hoover

US Patent:

44570112, Jun 26, 1984

Filed:

Sep 30, 1982

Appl. No.:

6/432075

Inventors:

Brian L. Hoover - South Bend IN

International Classification:

H04H 500

US Classification:

381 2

Abstract:

An FM broadcast band demodulator and stereo decoder which can be connected to an existing frequency modulated, or FM broadcast tuner or receiver. The unit includes four basic sections; FM demodulation, stereo decoding, audio amplification, and tuning error detection. The FM demodulation is done by an integrated circuit directly coupled to a second integrated circuit which performs the stereo decoding function. The function output signals of the second integrated circuit are re-centered to a direct current or d-c level of zero by voltage dividers and amplified by operational amplifiers to drive a load. The tuning error indicator is connected between the first and second integrated circuits and nullifies the d-c components from the output signal of the first integrated circuit before integrating the output signal to remove the audio portion and leave only an average d-c component. The remaining d-c signal is amplified and applied through a bridge rectifier to a light emitting diode or LED. The LED is lighted upon an imbalance of. +-.