| 摘要 |
PURPOSE:To eliminate the need for a status information bit by transmitting a burst frame while inhibiting number exchange at each burst with a polarity of a head bit during training period and allowing an opposite party to detect the end of the training period from the start of polarity inversion at each burst of the said polarity. CONSTITUTION:Line terminators 2, 4 have the same constitution. A burst signal transmitted on a subscriber line 3 is subject to switching control by a switch 31, decoded and a frame pattern is separated in a multiplex separation circuit 13 and the result is fed to a burst control circuit 30. On the other hand, a clock signal is generated based on the timing extracted by a timing extraction circuit 15. A frame synchronism circuit 17 discriminates the presence of synchronism establishment with the opposite party depending whether the frame pattern is detected or not at a prescribed point of time based on the said clock signal and an output of a decoder 12. Further, a polarity detection line 18 detects the end point of time of the training period by detecting the start of inversion of the polarity of the head bit in the frame pattern transmitted from the opposite party at each burst during the training period.
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