| 摘要 |
PURPOSE:To make the data transmission speed of a terminal device identical with the data transmission speed of a transmission line by sending random data to the same transmission line prior to call control data to dinstinguish the call control data transmission from the inter-terminal data transmission. CONSTITUTION:Random data is outputted to a transmission data switching circuit 2 as a signal A from a random data generating circuit 4, and a normal frame synchronizing word F, a sender address SA, a destination address RA and call control information CONT are outputted to a transmission data switching circuit 2 as a signal B from a call control data generating circuit 5. From the device in the call mode, the call control data signal B in succession with random data is sent to a transmission line via a transmission line interface circuit 9 from the circuit 2 as a signal G. In the device of the incoming mode, when call control data is confirmed by a call control data reception circuit 7, an E signal output is outputted to an operation discrimination control circuit 1 as a level of logical 1 and the reception of the call control data is confirmed in succession to the random data.
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