Automatic volume reduction stage for vehicle radio - has reducing stage triggered by signal from approaching public service vehicle e.g. police car

摘要

The radio receiver for a road vehicle has a facility to provide an automatic reduction in volume when a signal is received from an approaching public service-vehicle i.e. police-car or ambulance. Each service vehicle has a transmitting device that emits a warning signal to be received (2) by an amplifier in the road vehicle. A switching stage (3) is activated to operate an optical warning lamp (7) and also to control a volume reduction stage (4) coupled to the radio loudspeaker (6).