| 摘要 |
A radio signalling system includes a transmitter operating to transmit a continuous carrier signal periodically modulated with a tone signal burst. A receiver includes an amplifier-detector operating to recover the audio tone signal bursts, which are then amplified, threshold detected, and converted to corresponding output pulses. A discriminator, responding to the amplifier-detector output, enables a gate only during the intervals between tone signal bursts when unmodulated carrier is received. The output pulses are passed by the enabled gate and accumulated to ultimately effect triggering of switching means to initiate a remote switching function. Energization of the transmitter is achieved by selectively positioning a pivotally mounted battery to make an electrical contact between a battery terminal and a stationary terminal contact.
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