Importance

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Abstract

To counter the effects of multipath on the signal received at the receiver of an FM stereophonic broadcasting system utilizing companding of the stereo difference signal, the normal operation of the expander embodied in the receiver is automatically modified in response to detection of multipath so as to minimize such effects and thereby improve the quality of the reproduced signal. In the preferred embodiment, a substantially fixed or steady control voltage replaces the normal dynamically varying control signal for the variable gain element of the expander during occurrences of multipath disturbances in excess of a predetermined severity. Another aspect of this embodiment is that a D.C. correction voltage having an amplitude proportional to the severity of the detected disturbances is combined with the fixed control voltage for the variable gain element in a manner to reduce the gain of the element thereby to further reduce the effect of the disturbance.

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First Claim