Delco Electronics Corporation

Gordon Phillip Howlett

Gregory J Manlove

Thomas Gerard Block

Detlef Griessman

John Norris Reigler

A multipath interference reduction system and method for smoothly reducing noise associated with FM stereo signal reception with an adjustable blend. The system includes a peak detector for detecting noise present in the received signal. When the detected noise exceeds a first threshold limit, stereo separation reduction is provided. The amount of stereo separation reduction may be adjusted so as to provide a greater reduction at higher noise frequencies than at lower noise frequencies to enhance the audio sound. When the determined noise exceeds a second higher threshold limit, stereo separation is further reduced to provide primarily monoaural reception.

Multipath interference reduction system and method

A synchronous AM detector and processor requiring a reduced number of external components and fewer integrated circuit pins comprises an audio processor having a first filter operation controlled by a control voltage and an AM stereo decoder including a lock detector and a phase locked loop having a second filter operation controlled by the control voltage. A single control node is coupled to the audio processor and the phase locked loop, the control node providing the control voltage for the audio processor and the phase locked loop. The voltage at the control node is biased normally high, capable of being pulled low by the audio processing circuit and capable of being pulled low by the lock detector. An RC circuit decays the rise time of the control voltage at the control node after the control voltage has been pulled low. Circuitry is added to control the first filter operation of the audio processing circuitry responsive to the control voltage at the control node. Additional circuitry is added to control the second filter operation of the phase locked loop in response to the control voltage level.

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Greentown, IN, United States of America

Gordon Phillip Howlett