Granted Patent B1

US 8,947,812 · App. 14/227,896 · Granted Feb 3, 2015

Abstract

Claims (82)

1. A data storage device comprising:

a disk;

a head actuated over the disk; and

control circuitry configured to:

sample a read signal from the head to generate signal samples;

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

filter the equalized samples with an inter-track interference (ITI) filter to generate ITI attenuated samples; and

detect a data sequence based on the ITI attenuated samples,

wherein the ITI filter comprises a transfer function:

1−HPF( e k )

where:

e k represents a noise sequence in the equalized samples; and

HPF represents a high pass filter operating on e k .

2. The data storage device as recited in claim 1 , wherein the HPF comprises a form:

y k =αe k −(α e k-1 +βy k-1 )

where:

y k represents an output of the HPF; and

α and β are coefficients.

3. The data storage device as recited in claim 2 , where α and β are programmable coefficients.

4. The data storage device as recited in claim 1 , where the control circuitry is further configured to generate the noise sequence by computing a difference between the equalized samples and corresponding ideal samples.

5. The data storage device as recited in claim 4 , where the control circuitry is further configured to generate the ideal samples based on the detected data sequence.

6. The data storage device as recited in claim 4 , where the control circuitry is further configured to generate the ideal samples based on a test pattern written to the disk.

7. A data storage device comprising:

a disk;

a head actuated over the disk; and

control circuitry configured to:

sample a read signal from the head to generate signal samples;

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

filter the equalized samples with an inter-track interference (ITI) filter to generate ITI attenuated samples; and

detect a data sequence based on the ITI attenuated samples,

wherein the ITI filter comprises a transfer function:

1−LPF( e k )

where:

e k represents a noise sequence in the equalized samples; and

LPF represents a low pass filter operating on e k .

8. The data storage device as recited in claim 7 , wherein the LPF comprises a form:

y k =α( e k +βe k-1 )

where:

y k represents an output of the LPF; and

α and β are coefficients.

9. The data storage device as recited in claim 8 , where α and β are programmable coefficients.

10. The data storage device as recited in claim 7 , where the control circuitry is further configured to generate the noise sequence by computing a difference between the equalized samples and corresponding ideal samples.

11. The data storage device as recited in claim 10 , where the control circuitry is further configured to generate the ideal samples based on the detected data sequence.

12. The data storage device as recited in claim 10 , where the control circuitry is further configured to generate the ideal samples based on a test pattern written to the disk.

13. A method of operating a data storage device, the method comprising:

sampling a read signal from a head actuated over a disk to generate signal samples;

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

filtering the equalized samples with an inter-track interference (ITI) filter to generate ITI attenuated samples; and

detecting a data sequence based on the ITI attenuated samples,

wherein the ITI filter comprises a transfer function:

1−HPF( e k )

where:

e k represents a noise sequence in the equalized samples; and

HPF represents a high pass filter operating on e k .

14. The method device as recited in claim 13 , wherein the HPF comprises a form:

y k =αe k −(α e k-1 +βy k-1 )

where:

y k represents an output of the HPF; and

α and β are coefficients.

15. The method as recited in claim 14 , where α and β are programmable coefficients.

16. The method as recited in claim 13 , further comprising generating the noise sequence by computing a difference between the equalized samples and corresponding ideal samples.

17. The method as recited in claim 16 , further comprising generating the ideal samples based on the detected data sequence.

18. The method as recited in claim 16 , further comprising generating the ideal samples based on a test pattern written to the disk.

19. A method of operating a data storage device, the method comprising:

sampling a read signal from a head actuated over a disk to generate signal samples;

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

filtering the equalized samples with an inter-track interference (ITI) filter to generate ITI attenuated samples; and

detecting a data sequence based on the ITI attenuated samples,

wherein the ITI filter comprises a transfer function:

1−LPF( e k )

where:

e k represents a noise sequence in the equalized samples; and

LPF represents a low pass filter operating on e k .

20. The method as recited in claim 19 , wherein the LPF comprises a form:

y k =α( e k +βe k-1 )

where:

y k represents an output of the LPF; and

α and β are coefficients.

21. The method as recited in claim 20 , where α and β are programmable coefficients.

22. The method as recited in claim 19 , further comprising generating the noise sequence by computing a difference between the equalized samples and corresponding ideal samples.

23. The method as recited in claim 22 , further comprising generating the ideal samples based on the detected data sequence.

24. The method as recited in claim 22 , further comprising generating the ideal samples based on a test pattern written to the disk.

Assignments (8)