DISK REPRODUCING AND DEMODULATING DEVICE

摘要

PURPOSE:To always obtain an optimum phase by generating a control signal of an up-down counter of the next stage in response to the lead/lag of a detected sampling phase and using the counter output as an address signal so as to switch resampling clocks of plural number with different phase and to supply the result to an A/D conversion circuit. CONSTITUTION:The polarity of a horizontal synchronizing signal waveform 20 is inverted actually for each scanning line. Values of positions 22-24 are used for the actual operation among normal resample positions 21-24. Denoting each value by D1-D3, whether or not the resample position is led or lagged from the normal position is discriminated depending whether the value calculated by (D1+D3)/2-D2 is positive or negative and the deviation is calculated depending on the quantity. Thus, efficient resample clock phase control is attained.