Pulse or digital communications – Spread spectrum – Direct sequence
Patent
1981-05-13
1983-03-08
Safourek, Benedict V.
Pulse or digital communications
Spread spectrum
Direct sequence
375111, 455 34, 455 58, H04Q 704
Patent
active
043763103
ABSTRACT:
A channel busy arrangement for use in a radio-based data transmission system comprising a plurality of data terminals. A carrier activity signal (CAS) generated by a receiver associated with a data terminal is used to trigger a CAS pulse of approximately 300 msec. A demodulated audio signal from the receiver is coupled to a SYNC detector for detecting a data synchronizing (SYNC) signal generally transmitted before a data message and to an optional continuous tone coded squelch system (CTCSS) for generating a CTCSS signal. The CAS pulse, SYNC signal and CTCSS signal are logic ORed to generate a channel busy signal used for inhibiting data transmission. Thus, data transmission is inhibited only during a 300 msec CAS pulse, when a SYNC signal is present, or during valid non-data transmissions (voice) even in the presence of an interfering signal.
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Stackhouse Bill L.
Taylor Theodore E.
Chin Stephen
General Electric Company
Safourek Benedict V.
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