Building intercom system

摘要

A building intercom system (1) is presented and described with a power source (2), a floor microphone (3) and a floor loudspeaker (4) (= floor intercom station (5)) and with a door microphone (6) with an associated door microphone amplifier (7) and a door loudspeaker (8) with an associated door loudspeaker amplifier (9) (= door intercom station (10)), the power source (2), the floor microphone (3), the floor loudspeaker (4), the door microphone amplifier (7) and the door loudspeaker amplifier (9) being connected in series, only one line routed via the individual units therefore being provided to connect the power source (2), the floor microphone (3), the floor loudspeaker (4), the door microphone amplifier (7) and the door loudspeaker amplifier (9) and only two lines being provided to connect the floor microphone (3) and the floor loudspeaker (4) on the one hand and the door microphone amplifier (7) and the loudspeaker amplifier (9) on the other hand. In the building intercom system (1) according to the invention, acoustic feedback on the door intercom station (10) is eliminated in particularly elegant fashion by also supplying the door loudspeaker amplifier (9) with a compensation signal which is the inverse of the output signal of the door microphone amplifier (7). <IMAGE>