Predictive distortion reduction appts. for AM stereo transmitters - subtractively combines distortion cancelling components with stereo difference signal in multiplex modulation channel

摘要

The apparatus for generating a composite AM stereo broadcast signal in which a carrier is angle modulated with stereo difference information contained in a first supplied signal. The angle-modulated carrier is then amplitude modulated with stereo sum information contained in a second supplied signal, in which distortion is predicted by the use of a simulated transmitter and receiver. A correction signal is generated having distortion representative components. Correction signals developed in this manner are used to modify the angle-modulating signal utilising a feedback technique, a subtractive technique, or both. This reduces distortion in the output of the stereo difference signal channel of actual AM stereo receivers which receive the composite AM stereo signal.