| 摘要 |
An optical communications system, e.g. a telephone system, comprising means to accept even electrical communication signals from transmitting stations, modulate an optical signal with said signal from the transmitting station (20) and, using time-division-multiplexing, provide a resultant optical communication signal to a central station which utilizes a frequency-division-multiplexing system for handling incoming optical signals before passing the optical communication signals on the receiving station which utilises time-division-multiplexing means and, where necessary, reconverts the optical signal to an electrical communication signal. Particular advantages of the system are that it can handle and switch a very large number of signals and that it can be utilized in a hybrid communications system wherein, for example, users of the system can maintain conventional electrical entrance wiring (22) and conventional non-optical telephones and yet interface readily with optical street lines (26,28) of the system. Particular aspects of the invention are novel modulating and signal-selection devices. |
