04539706 is referenced by 122 patents and cites 6 patents.
A mobile vehicular repeater detects the termination of a received transmission from a portable transceiver to be repeated and, in response to such detection, activates the up-link radio transmitter so as to send an acknowledgement signal to the message originating portable transceiver station signifying the probable successful conclusion of a repeating operation. Special techniques are utilized to prevent confusion between such an acknowledgement signal and similar prioritizing transmissions on the up-link frequency.