| 摘要 |
PURPOSE:To send a data signal to a digital transmission line by one modulation by synchronizing a sampling clock of a transmission line with the clock speed of a data signal, using the clock so as to apply analog modulation processing to the data signal to be sent, converting it into a transmission line signal format and sending the result. CONSTITUTION:A clock from a digital transmission line is given to a terminal 9 and a clock generating circuit 7 recovers a sampling clock fS required by a modulation circuit 4 from the clock. Moreover, a clock fD synchronizing with the clock fS is generated from a phase synchronizing circuit 6 and the result is outputted to a terminal 2 as a transmission element timing signal ST. A data terminal equipment receives a transmission data SD synchronously with the signal SD from its terminal 1. The transmission data SD is subjected to pre-processing for the modulation in a transmission data pre-processing circuit 3 in a rate of fO and the modulation is applied in a rate of FS by the modulator 4. A format conversion circuit 5 is operated at a rate fS and an output signal of the modulator is converted into a code format suitable for the transmission line.
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