| 摘要 |
PURPOSE:To realize a highly reliable information transmission regardless of the earth potential by carrying out the information transfer between two areas possessing the earth potential via the optical cable. CONSTITUTION:PCM end office equipment 21 and 26 plus repeaters 22 and 23 are those installed in the existing communication system. And the optical transmission system comprising electricity-light converters 24 and 25 is incorporated into this communication system. Each of converters 24 and 25 consists of interface INT, electricity-light converter E/O and light-electricity converter O/E each. The bipolar signal used as the normal PCM signal receives a fixed bias to be converted to the optical signal and thus to be turned to the optical bipolar signal featuring the ternary level. |
