Class of fixed partial response targets in a PRML sampled data detection channel
US6249398A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 4, 1998 |
| Grant date | Jun 19, 2001 |
| Priority date | — |
| Expiry date | Mar 4, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/10296
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A new class of fixed partial response targets are disclosed for use in a PRML magnetic medium read channel. The preferred embodiment exhibits an equalization response characterized by the polynomial 7+4*D-4*D.sup.2 -5*D.sup.3 -2*D.sup.4, where D represents the unit delay operator. This read channel target provides improved matching to the inherent magnetic channel over the known canonical class of targets (1-D)(1+D) N, and thereby reduces equalization losses. The improved spectral matching reduces amplification of noise in the channel, thereby reducing bit-error-rates. The new class of targets also exhibits a spectral null at DC, reducing problems for offset cancellation circuitry and making the disk drive less sensitive to thermal asperities. It also exhibits a spectral depression rather than a spectral null at the Nyquist frequency, making quasi-catastrophic error sequences virtually impossible. The new class of target simplifies coding and allows RLL code ratios that approach unity, improving effective recording densities, while significantly reducing BER.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.