Scientific-atlanta, Inc.

David P Womble

Joseph Graham Mobley

Luis A Rovira

Allen Walter

Robert Dennison

A multiplication circuit for use in an FM television transmitter and receiver is provided. The multiplication circuit includes a limiting circuit for limiting a subcarrier supplied thereto and a dividing circuit coupled to the limiting circuit and dividing the output of the limiting circuit by a predetermined factor. A mixer is coupled to the dividing circuit and mixes the output of the dividing circuit with the subcarrier.

Method of subcarrier multiplication which preserves AM Information in FM

A FM demodulator system which provides threshold extension by frequency selective phase modulation of the input FM signal in a band pass filter to reduce phase error between the input and output of the filter. The output of the filter is applied to an FM discriminator which provides a base band signal. This base band signal is applied to a frequency selective phase compensation network to derive a signal which phase modulates the band pass filter. The filter rejects uncorrelated thermal noise so as to effect threshold extension in the demodulator system.

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Doraville, GA, United States of America

David P Womble