| 摘要 |
PURPOSE:To recognize the reception state of an opposite station in the center by executing the inquiry control for inquiring sequentially the reception state of each slave station in a multi-address mode after a picture signal is transmitted. CONSTITUTION:An operator in the center specifies the multi-address mode through an operational panel 7 to execute the multi-address transmission. Upon the completion of the transmission of the multi-address picture signal, a control circuit 12 switches again a changeover switch SW to the state as figure (c) shows, and outputs a reception recognition control signal to a control signal transmitting circuit 10. Thus said circuit 10 first outputs the address of an automobile 2-1 and an inquiry signal A1 for including a reception state inquiry signal. When the automobile 2-1 receives them, it returns an ACK signal for showing their normal reception to the center if the multi-address picture signal is normally received. The returned ACK signal is detected by a control signal reception circuit 11 through a receiving part 6, and the detection is transmitted to the control circuit 12, whereby said circuit 12 recognizes that the automobile 2-1 has received the multi-address signal normally.
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