Radio broadcasting system with code signalling

摘要

FM radio broadcasting is disclosed with code signalling by means of a subcarrier wave in the free frequency range around the stereo pilot on one side of said pilot (or of two subcarrier waves in said frequency range on both sides of the stereo pilot). The subcarrier wave, which is derived from the stereo pilot on the transmission side, is binary phase-modulated with the code signal, and is detected on the reception side with an unmodulated wave which is derived from the received stereo pilot.