| 摘要 |
This relates to a Transmitter/Receiver system which, coupled to an existing entry-phone installation, is used to control access to the building without the need to move to the conventional entry-phone set and displays the caller via the television screen. The necessary elements are: - For remote control/street panel communications (Fig. 1) a receiver located on the building's staircase 1, connected to the entry-phone's lead 2 and a radio transmitter for audio communications and door-opening 3. - For street panel/television communications (Fig. 2): a miniature video camera 1, a microphone 2 and a modulator 3. The modulator's radiofrequency signal is mixed with that of the existing collective aerial amplifier 4. The audio and video signals go to the user's television via the existing lead. <IMAGE>
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