Analysis of Cross Talk Between Radial Tilt Error and Tracking Error Signal of a High-Density Digital Disk

Abstract

Differential phase detection (DPD) and push-pull methods are widely used to generate tracking error signals in reading and writing high-density digital disks. Radial and tangential tilts, which will deteriorate the performance of the servo system, occur while the disk is spinning. Such influences vary with different tracking error generating methods and physical parameters of the disk. An analytic description of the disk diffraction model is obtained by diffraction theory. Disk radial tilt effects on tracking error signal and cross talk of read only and rewriteable disks are simulated and analyzed. A tracking error signal offset caused by radial tilt is 0.06 µ,m/deg on a DVD-ROM disk using the DPD method, 0.15 µ,m/deg using the push-pull method, and 0.12 µ,m/deg (0.10 pitch/deg) using the DPD method on a DVD-RAM disk. The DPD method exhibits better performance than the push-pull method when the disk is tilted on a DVD-RAM disk. The relationship between the tracking error signal offset and the groove depth is obtained in advance. The intertrack cross talk is also analyzed when disk tilt occurs.