| 摘要 |
PROBLEM TO BE SOLVED: To improve the quality of a demodulated signal by expressing a signal to be the sum of a phase difference component parallel with an I axis and a noise component of which phase is rotated with the lapse of time as a vector provided with the component parallel with the I axis and a component parallel with a Q axis, averaging the signal to reduce only the noise component and outputting the noise-reduced signal as a phase control signal. SOLUTION: A reverse modulation circuit 17 outputs a signal expressing a phase difference to be the sum of a real phase difference component parallel with the I axis and a noise component of which phase is rotated with the lapse of time as a vector provided with the component parallel with the I axis and a component parallel with the Q axis. An averaging circuit 6 averages the vector signal and cancels only the noise component to obtain a signal close to the real phase difference and a diffusion code generating circuit 7 generates a diffusion code based on the obtained signal. A delay 8 delays only a specific period corresponding to one bit of the diffusion code and a delay 9 delays the signal only by the same period and outputs the delayed signal to a correlator 1. Consequently the generation of jitter can be suppressed and the quality of a demodulated signal-outputted from a judging circuit 14 can be improved. |
