PURPOSE: To receive only the supervisory signal SV of a line of other direction without generating hindrance by providing an input interruption detector to a repeater so as to stop the extraction function of the supervisory signal SV of the line of a direction when input interruption is detected by decreasing the signal input of one direction of line.
CONSTITUTION: When the signal input of the incoming line is decreased during repeater receives the input signal of outgoing/incoming lines, noise is increased in the supervisory signal SV of the incoming line sent by the supervisory signal extracting means 3 of the incoming line and finally only noise exists. If the signal input of the incoming line is decreased, the level of a clock (c) extracted by the timing extracting device 2 of the incoming line is decreased. An input interruption detector 5 detects the level decrease in the clock(c) to output a detection signal (d). Then the outputted detection signal (d) interrupts the input of the signal data from a discrimination reproducing device 1 in the supervisory signal extracting means 3 to stop the extraction function of a supervisory signal. Thus, the nose or the supervisory signal SV with increased noise sent from the supervisory signal extracting means 3 of the incoming line to a command receiving means 4 is interrupted. As a result, only the supervisory signal SV from the outgoing line offering normal reception is inputted to the command reception means 4 of the incoming line.
TANIGAWA KAZUYUKI
KOIKE KIYOYUKI
MIYAZAKI TAKASHI
