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.

Abstract: An electronic organ includes a plurality of buffers for receiving solo keyswitch status information, accompaniment keyswitch status without octave information, and depressed keyswitch status from an arpeggio keyboard. A scan circuit and a microprocessor gate the buffers into an input memory which retains an image of the solo, accompaniment, and arpeggio keyboards. A control program, stored in ROM, is responsive to the input memory, shared registers, and harmony switches actuable in several modes, to produce one or plural harmony notes in either open or closed harmony, and to assign different note names to the actuated keyswitches on the arpeggio keyboard. The resulting harmony and arpeggio notes are stored in an output memory and are transferred to a transistor matrix which activates solo keyers to produce harmony and arpeggio notes with solo voicing. A rhythmic harmony modulator is actuable to modulate the harmony notes in a rhythmic pattern of individual and delayed beats.