| 摘要 |
The frequency of a coherent optical transmission wave (16) is temporarily offset during modulation pulses so as to give rise to an alternate succession of phase shifts modifying this wave into a representation coded by a succession of bits to be transmitted. These modulation pulses are supplied by a coder (2) which controls the frequency of a laser emitter (14) injecting the transmission wave into an optical fibre (24). According to the invention, the characteristic duration (D) of these pulses lies between 15 and 35% of the duration (T) of the bits to be transmitted. Heterodyne reception means include a local oscillator (26), an optical mixer (30), a photodetector (34), and a demodulator (46). The invention applies to telecommunications. <IMAGE> |
