| 摘要 |
<p>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 modifying means (3), such as a length of dispersive optical fibre, is used to modify characteristics of the sidebands so that the beat 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 frequency and therefore carried by the microwave link (6).</p> |
