Hard disk drive having a built-in self-test for measuring non-linear signal distortion
US6208477A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1997 |
| Grant date | Mar 27, 2001 |
| Priority date | — |
| Expiry date | Jun 6, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a hard disk drive, a semiconductor chip includes a circuit used in a built-in self test ("BIST") to determine an amplitude of a dibit echo for characterizing nonlinear distortion of a readback signal. Preferably, write precompensation is performed based on results of the BIST to minimize distortion attributable to intersymbol interference. A generator is used to generate a maximal length pseudo-random sequence. This maximal length pseudo-random sequence is input to a correlator which performs a correlation between the maximal length pseudo-random bit sequence and a readback signal responsive to the pseudo-random sequence that was stored onto a disk of the hard disk drive. In one embodiment, a seed value stored in memory is loaded into the generator upon detection of a synchronization signal read from the disk. With the appropriate seed value loaded into the generator, a specific pseudo-random bit sequence corresponding to a sample point of interest is then generated. The cross-correlation between this specific pseudo-random sequence with the readback signal produces a sample point corresponding to the dibit echo. By iteratively generating sample points corresponding to the echo,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.