PRE-BLOCK CONTROL SYSTEM OF SINGLE RADIO CIRCUIT

PURPOSE:To ensure the minimum necessary transmission of the blocking signal and to prevent the disturbance to other radio stations, by transmitting the blocking signal from a control office only when a call signal is transmitted from an end office and then setting each end office into the blocking state. CONSTITUTION:When a general command is required, a pre-blocking signal CS is transmitted from a relaying exchange REX by an operation of a control board to be stored in a pre-blocking control part CLC. When the transmission/reception of a communication signal is over, the part CLC is set in the queuing state by the release of a repeating circuit REP. Then the call signal transmitted from a terminal office is received by a signal receiver SR, and this information is given to the part CLC. Thus the part CLC gives a command to a transmitter SS for the transmission of the blocking signal and at the same time gives a command to a control part COT to send a start signal S. After this, the terminal office receives and stores the blocking signal, and maintains the blocking state.