| 摘要 |
An optical source for a communications system comprises an optical signal source (1) whose output is modulated so as to contain sidebands. The sidebands interact to produce beat frequencies and modify ing means (3), such as a length of dispersive optical fibre, is used to modify characteristics of the sidebands so that the be at frequency can be detected at a receiver (4) comprising a photodetector. In this way, high frequency signals can be generated and photodetected, the output of the receiver (4) being suitable to drive a microwave antenna (5), thus providing an optically fed microwave communications link (6). Using a video signal generator (11), a video signal can be superimposed on the received beat f requency and therefore carried by the microwave link (6).
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