Patent ID: 7433286
Filing Date: 2008-10-07
Classification: G11B

Abstract:
1. A jitter detection apparatus for detecting jitters which occur when playing an optical recording medium on which digital data are recorded using recording codes having a restriction that at least three same codes should be continued, comprising: a playback signal detection circuit for detecting a playback Radio Frequency (RF) signal from the optical recording medium; a PLL circuit for sampling the playback RF signal with a sampling clock that is synchronized with a cycle twice as long as a clock component included in the playback RF signal to output a digital RF signal after removal of an offset in an amplitude direction; a Nyquist interpolation filter for receiving, as an input signal, the offset-removed digital RF signal, and generating a first demodulation preprocessing signal for delaying the input signal by a predetermined period of time, and a second demodulation preprocessing signal which is a missing component in a time direction; a jitter detection preprocessing circuit for thinning out the first and second demodulation preprocessing signals at predetermined intervals according to the playback speed of the optical recording medium, in positions where the first demodulation preprocessing signal and the second demodulation preprocessing signal have opposite polarities, thereby extracting a capture signal which indicates a jitter detection source signal from which jitter information is to be extracted, and a hold timing of the jitter detection source signal, and outputting the capture signal; and a digital signal operation circuit for holding the jitter detection source signal at the hold timing indicated by the capture signal, and extracting jitter information from the jitter detection source signal.