| 摘要 |
PROBLEM TO BE SOLVED: To provide a synchronization-retaining apparatus and a synchronization-retaining method for retaining the correlation detection timing between a modulation impulse and a diffusion code series by a configuration or a method that is simpler than the conventional one when a modulation impulse train that is subjected to direct diffusion and pulse position modulation is to be demodulated. SOLUTION: A reception signal Srf is compared with a reference level at specific timing in synchronization with a reference clock signal Sck, and the level in the reception signal Srf is decided according to the comparison result. An inverse diffusion signal S303 according to the combination of a diffusion code S302 that is successively supplied in synchronization with the reference clock signal Srf and the judgment result of a level at a level judgment section 301 is generated. Then, in synchronization with the reference clock signal Sck, the inverse diffusion signal S303 is integrated for each period. After that, the difference of an integral value Dr corresponding to transmission data '1' and transmission data '0' is detected, and the frequency of the reference clock signal Sck is adjusted according to the detection result. |
