| 摘要 |
PROBLEM TO BE SOLVED: To reduce the disturbance of a transmission pulse signal duty ratio at the time of transfer by discriminating the positive/negative logic of a transmission signal by discriminating the positive/negative logic of a received signal corresponding to odd-number and even- number divisions in the exchange numbers of a present station and a preceding station. SOLUTION: When the present station has the odd-number exchange number and the preceding station has the even-number exchange number, an exchange number discriminating part 5 sets a received inverted signal RI invalid and sets a transmission inverted signal S1 valid. Therefore, the non-inverted positive logic pulse signal of preceding station transmission is passed through an OR circuit 4 in a logic mode, inverted by a transmission XOR circuit 71 together with the signal SI and transmitted through an optical transceiver 2 to the next station. At the station having the even-number exchange number, on the other hand, the signal RI from the discriminating part 5 is set valid, the signal SI is set invalid, and a negative logic inverted pulse signal from the preceding station having the odd-number exchange number is inverted by a reception XOR circuit 7 and inputted through the circuit 4 to the circuit 71 as a received signal RS but since the invalid signal SI is also inputted to the circuit 71, the positive logic signal passed through the circuit 4 becomes the driving signal of the transceiver 2 as it is, and the positive logic pulse signal is outputted to the next station. |
