| 摘要 |
In a remote control system especially suitable to use as an alarm system utilizing the bidirectional transmission line of a wired television broadcasting system and including a plurality of low frequency signal transmitters, a plurality of group modulators for modulating high frequency carrier waves by a plurality of groups of low frequency signals from the transmitters to transmit the group modulated waves as super group signals over the transmission line, a plurality of group demodulators for group demodulating the super group signals into group modulated waves of discrete groups, a plurality of detectors for detecting the group signals from the group demodulators to derive out a plurality of low frequency signals, a plurality of resonators each resonating to a predetermined frequency component of the low frequency signals produced by the detectors, and a plurality of controlled apparatus connected to be controlled by the output from respective resonators, there is provided frequency converting means installed on the input side of the group demodulators for converting the super group signals into signals having carrier frequencies lower than the former carrier frequencies of the super group signals.
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