antenna 6 duplexer 7 receriver 8 and decoder 9 at originating call signal detector 13 the line concentrator 5 proceeds to connect the time slot of the originating call to the switching system 12 in fig7 during idle times each of the repeater stations is constantly receiving bs sync signals transmitted from the base station the received bs sync signal is conducted through antenna 19 duplexer 21 receiver 23 and regenerator 27 to bs sync detector 36 which delivers an output signal to delay circuit 37 and to timer 35 at the same time the regenerator 27 regenerates a bs sync signal and transmits it through transmitter 25 duplexer 20 and antenna 18 to repeater and terminal stations the delay circuit 37 introduces a delay t 0 as shown at fig9 to wait for the regenerated bs sync signal to be transmitted after transmission of the regenerated bs sync signal the delay circuit 37 resets the flip flop 34 which in turn provides a turn off signal through or gate 33 to the power switch 28 whereby power supply from source 29 to receivers 22 23 and transmitters 24 and 25 is cut off concurrently the timer is performing a timing action in response to the output of bs sync detector 36 so that at the end of an interval t 1 from the onset of the timing action the flip flop 34 is triggered into a set condition when this occurs a turn on signal is supplied to the switch 28 to reactivate receivers 22 23 and transmitters 24 25 therefore a subsequent bs sync signal will be received at time which is delayed by an interval t 2 fig9 as seen in fig1 the bs sync signals are relayed by repeater.