| 摘要 |
In an alarm system utilizing a bidirectional wired television system, there are provided a plurality of alarm signal generators which are located on the subscribers' side, the signal generators generating low frequency alarm signals of the frequencies common to respective group units, the frequencies being different for respective subscribers in respective group units, each alarm signal generator being provided for each subscriber's modulators for respective group units; modulators for respective group units for modulating the low frequency alarm signals from the alarm signal generators with different high frequency carrier signals, and a receiving panel for receiving the modulated alarm signals. The receiving panel is provided with a plurality of demodulators for respective group units, first bandpass filters corresponding to the high frequency carrier signals utilized for modulation and adapted to apply the modulated alarm signals to the demodulators, first display means responsive to the outputs of the demodulators for providing displays for respective group units, a plurality of second bandpass filters corresponding to the low frequencies for respective subscriber's, means to supply the outputs of all demodulators in common to the second bandpass filters, and second display means connected to the outputs of the second bandpass filters for providing second displays for respective subscribers.
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