Circuit arrangement for the automatic adaptation of the volume of a loudspeaker to a disturbing noise level prevailing at the loudspeaker location

摘要

A circuit arrangement is specified for the automatic adaptation of the volume of a loudspeaker to a disturbing noise level prevailing at the loudspeaker location, in particular for mobile broadcast radio receivers, which circuit arrangement balances itself following installation of the mobile broadcast radio receiver at the reception location and automatically corrects its balance when changes occur in the conditions at the reception location. The circuit arrangement has a volume control (10), a microphone (18) which picks up the loudspeaker signal and the disturbing noise signal, a voltage amplifier (22-25) connected to the loudspeaker input, and a summation circuit (20) which combines the microphone output voltage and the output voltage of the voltage amplifier (22-25) with opposite polarity. For automatic balancing purposes, a control circuit (26) is provided which has a memory (34) for storing at least one gain and a computing component (35) for calculating a corrected gain from the stored value as a function at least of the setting of a loudspeaker adjuster (15), and a program part (36) with a program memory (37) and a program execution controller (38) for automatic calculation of the stored gain. IMAGE