| 摘要 |
<p>At a transmitting end, transmission signals corresponding to more than one channel are allocated different microwave frequencies and carriers of the microwave frequencies are modulated with the transmission signals in modulators. A filter (32-1 to 32-k) is placed in the preceding or succeeding stage of a respective modulator (31-1 to 31-k) to band-limit a corresponding transmission signal before or after modulation. The band-limited and modulated transmission signals are combined to produce a microwave frequency-division multiplexed signal. The multiplexed signal modulates an optical frequency modulator (33) to produce an optical modulated signal. The optical modulated signal is transmitted to the receiving end. At the receiving end, the optical signal transmitted from the transmitting end is detected and converted to an electrical signal. The channel components are extracted from the electrical signal by bandpass filters (36-1 to 36-k) and then demodulated. A local optical mixer is used for converting the received optical signal into a signal having an intermediate optical frequency. <IMAGE></p> |
