A Monolothic 4-Channel/Stereophonic Decoder for an FM Broadcast System With Pilots

The General Electric Company has expanded the 2-channel FM stereo broadcast systeml into a discrete 4-channel system2,3,4, that is compatible with present day stereo and monaural receiver equipments. Future receiver systems designed to decode the discrete 4-channel signal must incorporate a low cost decoder which is also functionally compatible with monaural and stereo transmissions. Consideration in the design of the decoder include the format of the composite signal, desired performance levels, technology selection and cost.