Audio equipment incorporating RDS receiver - includes muting circuit for suppression of noise emission during intervals of reception interference of mobile antenna

摘要

The audio equipment has a source selector (19) which switches compact disc and audio tape players (20,21) and the radio data receiver (1a) for connection through an audio amplifier (22) to stereo loudspeakers (23a,23b). A 57 kHz FM data subcarrier is filtered (6) and demodulated by a phase locked loop (7). A detector (11) of decoded data gp. or block synchronisation and an error correction stage (12) cause the controller (13) to switch on an audio attenuator (18) in the receiver and suppress prodn. of noise during temporary loss of RF signal at the antenna (1). When reception conditions are not good enough for all stations in an AF-list, the audio output is switched to another music source. When reception conditions are good enough, the audio output is switched to one of the RDS stations. USE/ADVANTAGE - In road traffic information system, no unacceptable audio noise is emitted even when reception is interrupted by tunnel or other overhead structure.