| 摘要 |
PURPOSE:To execute a time signal broadcast without troubling a dispatcher's hand by providing a function for controlling automatically an operation of a monitor loudspeaker of each telephone device on a dispatching place. CONSTITUTION:When start information is sent out of a time setting circuit 11b of a control device of a dispatching place, a telephone set control circuit 11a sends out a loudspeaker start signal to 20 telephone sets 5. As for this signal, three short codes are added to the end of each cycle of a usual call start signal. In each telephone set 5, it is discriminated that when the number of pulses in one cycle of the start signal is 20, it is a usual call, and when said number is 23, it is a loudspeaker start. If the own number pulse position is a long code, a confirming signal is send back from the telephone set 5. They are controlled by a signal selecting circuit 5b, and an (m) contact for connecting a loudspeaker circuit 5a and a communicating circuit 4 is operated by its output. From this time, the confirming signal is stopped, the control circuit 11a stops a sending-out signal, and simultaneously, by its detecting output, an A relay of a dispatching board 10 is operated, and a transmitter and receiver circuit 10a is switched to a time signal generating source 10b at a contact (a). |
