| 摘要 |
PURPOSE:To simplify the constitution by stopping a call signal from a subordinate station while an interphone is busy, by using a calling switch with which a master station calls the subordinate station. CONSTITUTION:The master station and subordinate station are connected via transmitter-receives 1 by radio. For calling from subordinate station to the master station, tone signal f3 and tone signal f2 are used and the master station excits relay RY-1 by detecting signal f2 by detecting circuit 16 to operate transmitting circuit 5, and then close relay contact RYS-21 by exciting relay RY-2 to connect a circuit. On the detection of signal f3, relay contact RYS-3 is changed over to disconnect the line wire and a calling signal is generated by call generating circuit 23. Next, the master station closes calling switch 14 to stop the operation of call generating circuit 23 and, since relay contact RYS-22 is still open, stops the generation of the calling signal at the subordinate station without tone signal f1 generated. Thus, the calling switch is shared to simplify the constitution. |
