System for minimizing the effects of scratches on recording media

摘要

A system is disclosed which significantly reduces the susceptibility of a recording media to data loss due to scratches. The system uses a signal generator function to inject a periodic, small amplitude dither signal into the head positioning servo system during a write or preformatting operation to the media. This dither signal is typically sinusoidial and causes the data tracks to effectively wander back and forth over longitudinal scratches on tape media or circular scratches on disk media. The data tracks are thus never coincident with a large portion of the scratch. During read-back of the media, a tracking servo system in the tape or disk drive follows the data written on each dithered track. Since the amplitude, period, and shape of the dither's periodic offset are fixed and known in advance, the servo can effectively track the data on the tape without compromising head positioning performance. Freed from correcting scratch induced errors, the error detection and correction circuitry used with the drive system can be simplified and/or optimized to better handle non-scratch related errors.