| 摘要 |
PROBLEM TO BE SOLVED: To provide a subcarrier transfer circuit capable of system control by using a stable subcarrier by avoiding that a CNR of a subcarrier signal is deteriorated through conversion of a data pattern of a digital signal. SOLUTION: A transmitter side circuit 10 is provided with a subcarrier high frequency oscillator 12 outputting a subcarrier signal with a frequency being an integer multiple of that of an NRZ digital signal from a digital signal generating circuit 11, an output of the subcarrier high frequency oscillator 12 is modulated by a modulator 13, a synthesizer 14 synthesizes the NRZ digital signal and the subcarrier signal to superimpose them, the superimposed electric signal is converted into an optical signal and the signal is sent to a transmission line 16. A receiver side circuit 20 distributes the optical signal from a transmission line into two, and a digital signal optical receiver 22 receives only the digital signal from the distributed signal and a subcarrier optical receiver 23 receives only the subcarrier signal. |
