| 摘要 |
Surveillance and control device for communal entrances, of the kind that comprises a permanently connected video camera at a point that optimizes the focusing on the person calling, characterized by the fact that it uses its own collective TV aerial system with the addition of a video- audio modulator (modem) and a VHF or UHF signal amplifier, the communal-entrance images captured by the camera being transmitted to the modulator via a coaxial cable as an electronic video signal, for the modulator to electronically alter the video-audio signal into a VHF or UHF signal, whose modulator is connected to the VHF or UHF signal amplifier, being tuned to a free TV channel and this channel being auto- mixed with a "Z" system for entering the existing TV amplifier group in the apartments, and this amplifier group sending the different TV signals to the distribution box and the images captured by the camera to all the domestic TV collective receivers. <IMAGE>
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