| 摘要 |
PURPOSE:To easily mount a multiple dwelling housing doorphone camera system by adopting multiplex signals for the communication between outdoor unit installed at the entrance of a multiple dwelling housing and indoor units installed each house of the said multiple dwelling housing so as to use a couple of communication line as signal transmission line. CONSTITUTION:The titled system is constituted of the outdoor unit 100 installed at the entrance of the multiple dwelling housing and plural indoor units 300 installed in each house of the said housing, a couple of communication lines L connected between the outdoor unit 100 and each indoor unit 300 and a repeater 200 as a power supply device supplying a DC power to each indoor unit 100 via the line L. The repeater 200 is provided with a video FM demodulation circuit 201 demodulating an FM modulation video signal included in a multiplex signal sent from the outdoor unit 100 to discriminate the address signal and an address signal detector 202 to detect the address signal from the demodulated video signal. Thus, the doorphone camera system is realized comparatively inexpensively.
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