Communications: electrical – Condition responsive indicating system – With particular coupling link
Patent
1977-09-13
1978-09-12
Waring, Alvin H.
Communications: electrical
Condition responsive indicating system
With particular coupling link
340310R, 325308, G08B 108
Patent
active
041141504
ABSTRACT:
In an alarm system utilizing a bidirectional wired television system, there are provided a plurality of alarm signal transmitters which are located on the subscriber's side, the signal transmitters generating low frequency signals of the frequencies common to respective group units, the frequencies being different for respective subscribers in respective group units, each alarm signal transmitter being provided for each subscriber, modulators for respective group units for modulating the low frequency signals from the alarm signal transmitters with different high frequency carrier signals, and a receiving panel for receiving the modulated signals. The receiving panel is provided with a plurality of demodulators for respective group units to demodulate the modulated signals and thereby to discriminate the group units in accordance with the high frequencies of the carrier signals, a plurality of detectors for receiving in common the outputs of the demodulators to detect the demodulated signals and thereby to discriminate the subscribers in accordance with the low frequencies of the low frequency signals, a plurality of display devices provided one for each alarm signal transmitter and grouped in the same manner therewith so as to be selectively actuated by the output of the detectors in common in respective groups and thereby to allow each subscriber to provide a corresponding display, and switching means and a scanning controller for sequentially energizing both the demodulators and the group units of the display devices.
REFERENCES:
patent: 3996578 (1976-12-01), Takeuchi et al.
Masuda Hajime
Yamazaki Shunji
Hochiki Corporation
Waring Alvin H.
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