| 摘要 |
<p>When an information track on a record carrier (2) is read detection signals (IA, IB, IC and ID) are obtained which depend on the information pattern being read. By means of n-bit analog-to-digital converters (16a, 16b, 16c and 16d) these detection signals (IA, IB, IC and ID) are converted into series of signal values (ua, ub, uc and ud). From these signal values (ua, ub, uc and ud) a data signal (SD) is derived which is representative of the information being read. From the signal values (ua,ub, uc and ud) series of signal values (va, vb, vc and vd) are derived which represent only the low-frequency information of the detection signals (IA, IB, IC and ID). For this purpose each of the signal series (ua, ub, uc and ud) is applied to a cascade arrangement of a quantising circuit (21a, 21b, 21c and 21d) and a decimating filter (22a, 22b, 22c and 22d). These signal values (va, vb, vc and vd) are employed for deriving control signals (SR, SF), for example for tracking of the information track.</p> |
