| 摘要 |
An airborne radio-telephone transceiver is provided having improved channeling and decode circuitry compatible with the selective signalling call-up system prescribed by the Federal Communications Commission. The decode circuitry includes a filter and detector dependent only on reception of a single selected frequency transmitted as a call-up signal by a ground station. A retriggerable, resettable, monostable multivibrator, configured as a pulse swallower, provides the necessary counter offset for proper call-up signal decoding. The invention includes scanning circuitry for rapid operator selection of active transmit-receive channels in the operator's geographic area.
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