| 摘要 |
PROBLEM TO BE SOLVED: To eliminate intrinsic noise in a system caused by crosstalk from other signals and tracking process by processing an input signal from an optical pickup by a zone band-pass filter and a limiter, eliminating low-frequency components from the input signal, and outputting a missing wobble pulse by eliminating noise from the product of the two signals. SOLUTION: A missing wobble detector 170 generates a continuous square- wave output of a wobble frequency by a zone band-pass filter 220 and a limiter 240 from a normalized push-pull tracking error signal inputted via a buffer 210. On the other hand, the detector eliminates low frequency noise through a high-pass filter 250. Next, it obtains the product of the signals from the high- pass filter 250 by an analog multiplier 260 and the limiter 240, and following this operation it smooths the product with low-pass filter, and eliminates low frequency variations through a high-pass filter 280, and outputs a digital signal showing the presence or absence of a wobble signal by a threshold value comparator 290.
|
