OPTICALLY READABLE DIGITAL INFORMATION DISC AND MANUFACTURING RECORDING AND REPRODUCING APPARATUS THEREFORE

摘要

PHN. 9667. A record carrier comprising a disc-shaped substrate with a radiation-sensitive information layer and provided with information areas arranged in accordance with a spiral or concentric track pattern. The record carrier is intended for the recording and/or reproduction, via a radiation beam, of digitally coded information of fixed bit frequency in the information areas. The information areas exhibit an optically detectable first periodic track modulation, whose period corresponds to a frequency for which the power spectrum of the digitally coded information substantially exhibits a zero point, for generating a clock signal of bit frequency during recording and/or reproduction. In order to generate a radial tracking signal during recording and/or reproduction, there is superimposed on the first periodic track modulation a second periodic track modulation, in which the track position is modulated in a radial direction. The period of the second track modulation is at least as the same order of magnitude as the period of the first periodic track modulation.