| 词条 | Four-wire circuit |
| 释义 |
In telecommunication, a four-wire circuit is a two-way circuit using two paths so arranged that the respective signals are transmitted in one direction only by one path and in the other direction by the other path. Late in the 20th century, almost all connections between telephone exchanges were four-wire circuits, while conventional phone lines into residences and businesses were two-wire circuits. The four-wire circuit gets its name from the fact that, historically, a balanced pair of conductors were used in each of two directions for full-duplex operation. The name may still be applied to, for example, optical fibers, even though only one fiber is required for transmission in each direction. A system can separate the frequency directions by frequency duplex and realize the benefits of a four-wire circuit even while the same wire pair is used in both directions. References{{FS1037C MS188}}{{telecommunications}}{{telephony-stub}} 2 : Communication circuits|Telephony |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。