Abstract: A track count estimator is provided for an optical storage device operating in either a CD-ROM mode or a DVD mode during a track seek. The track count estimator includes a state estimator to determine current and predicted estimates of the position and velocity of an optical pickup in the optical storage device according to the following equations:Current Estimate: X(k.vertline.k)=X(k.vertline.k-1)+K(Z(k)-X.sub.1 (k.vertline.k-1))Predicted Estimate: X(k+1.vertline.k)=Ad.multidot.X(k.vertline.k)The input to the state estimator can be selected from a CD-ROM signal (if the optical device is operating in a CD mode) or a DVD signal (if the optical device is operating in a DVD mode), the selected signal representing a half-track position error. An error signal is then generated which is processed separately in position and velocity portions of the state estimator.

Abstract: A system and method for generating a unique sync pattern that may be appended to a selected data sector of a disk storage system. The data to be stored in the disk storage system is encoded in accordance with a desired fixed rate run-length limited code, such as a 2,7 code. The unique sync pattern is generated by first encoding a prescribed data word in accordance with the desired code. At least one bit of the encoded prescribed data word is then changed in a manner such that the changed encoded word still complies with the coding rules of the desired code, yet the resulting bit pattern does not represent any valid sequence of data in accordance with the desired code. Hence, the changed encoded word may be readily distinguished from data, thereby providing the synchronization function, while still being handled and processed by the same encoding/decoding circuitry as is employed to handle and process the data.