| 摘要 |
The present invention relates to a method and apparatus for selectively enabling and disabling transmit and receive functions of a radio (figure 1A) , and more particularly to a system and method utilizing an out-of-band signal over a time division duplex channel to control transmit (11) and receive (12 ) functions of a radio so as to synchronize with the functions of a remote mod em (figure 2, 40). The invention relates to a system and method for synchronizi ng the transmit and receive modes of a radio via an out of band signal. The out of band signal is preferably a control tone at a predetermined frequency and is substantially coextensive with the communication signal to be transmitted . The radio filters a multiplexed signal and detects if the control tone is present. If the control tone is not detected, the radio preferably remains i n the default receive mode. If the control tone is detected, the radio operate s in the transmit mode for the duration of the control signal.
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