Granted Patent B1

US 8,896,949 · App. 13/789,071 · Granted Nov 25, 2014

Abstract

Claims (27)

1. A disk drive comprising:

a disk;

a head actuated over the disk; and

control circuitry operable to:

read data from the disk to generate a read signal;

sample the read signal to generate signal samples;

filter the signal samples with an equalizer filter to generate equalized samples;

filter the equalized samples with a general noise whitening filter independent of any data pattern generated by a sequence detector to generate general noise whitened samples;

filter the general noise-whitened samples with a bank of data dependent noise whitening filters to generate data dependent noise whitened samples; and

detect a data sequence from the data dependent noise whitened samples.

2. The disk drive as recited in claim 1 , wherein the control circuitry comprises a trellis type data detector operable to detect the data sequence, wherein the trellis type data detector comprises a target substantially matched to a channel response represented by an output of the general noise whitening filter.

3. The disk drive as recited in claim 2 , wherein:

the trellis type data detector comprises a plurality of states;

each state generates at least two branch metrics; and

each state is responsive to an output of at least two of the data dependent noise whitening filters.

4. A method of operating a disk drive comprising a head actuated over a disk, the method comprising:

reading data from the disk to generate a read signal;

sampling the read signal to generate signal samples;

filtering the signal samples with an equalizer filter to generate equalized samples;

filtering the equalized samples with a general noise whitening filter independent of any data pattern generated by a sequence detector to generate general noise whitened samples;

filtering the general noise-whitened samples with a bank of data dependent noise whitening filters to generate data dependent noise whitened samples; and

detecting a data sequence from the data dependent noise whitened samples.

5. The method as recited in claim 4 , further comprising detecting the data sequence using a trellis type data detector comprising a target substantially matched to a channel response represented by an output of the general noise whitening filter.

6. The method as recited in claim 5 , wherein:

the trellis type data detector comprises a plurality of states;

each state generates at least two branch metrics; and

each state is responsive to an output of at least two of the data dependent noise whitening filters.

Assignments (8)