Data storage device demodulating servo stripes using matched filter

1. A data storage device configured to access a magnetic media comprising a plurality of servo frames each comprising an A servo burst, a B servo burst, a C servo burst, and a D servo burst, the data storage device comprising:

at least one head configured to access the magnetic media; and

control circuitry configured to:

read the A servo burst in a first servo frame using the head to generate a first read signal;

sample the first read signal to generate first signal samples;

use a first matched filter matched to the A servo burst to filter the first signal samples to generate first filtered samples within a first burst window;

first update the first burst window based on the first filtered samples;

process the first filtered samples within the first burst window to generate a position error signal (PES); and

control a position of the head relative to the magnetic media based on the PES.

2. The data storage device as recited in claim 1 , wherein each servo burst comprises a plurality of servo stripes.

3. The data storage device as recited in claim 1 , wherein the data storage device further comprises the magnetic media, and the magnetic media includes magnetic tape.

4. The data storage device as recited in claim 1 , wherein:

the magnetic media is housed in a cartridge assembly; and

the data storage device further comprises a tape drive assembly configured to receive the cartridge assembly.

5. The data storage device as recited in claim 1 , wherein the first burst window estimates a center of the A servo burst in the first servo frame, and the control circuitry is further configured to:

read the A servo burst in a second servo frame using the head to generate a second read signal;

sample the second read signal to generate second signal samples;

use the first matched filter matched to the A servo burst to filter the second signal samples to generate second filtered samples within the first updated first burst window; and

second update the first burst window based on the second filtered samples.

6. The data storage device as recited in claim 5 , wherein the control circuitry is further configured to:

measure an A-A burst interval representing an estimated time ta from the center of the A servo burst in the first servo frame to a center of the A servo burst in the second servo frame; and

second update the first burst window based on the estimated time ta.

7. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to:

generate a second burst window based on the estimated time ta;

read the C servo burst in the first servo frame using the head to generate a third read signal;

sample the third read signal to generate third signal samples;

use a second matched filter matched to the C servo burst to filter the third signal samples to generate third filtered samples within the second burst window; and

process the third filtered samples to generate the PES.

8. The data storage device as recited in claim 7 , wherein the control circuitry is further configured to generate the second burst window based on a predetermined fraction of the estimated time ta.

9. The data storage device of claim 7 , wherein:

the control circuitry is configured to read a second servo burst using the head, wherein the A servo burst and the B servo burst are part of a first subframe, and the C servo burst and the D servo burst are part of a second subframe;

at least one of the A servo burst, the B servo burst, the C servo burst, or the D servo burst has a missing or unreadable servo stripe; and

the first subframe has a first width and the second subframe has a second width equal to the first width.

10. A data storage device configured to access a magnetic media comprising a plurality of servo frames each comprising an A servo burst, a B servo burst, a C servo burst, and a D servo burst, the data storage device comprising:

at least one head configured to access the magnetic media; and

control circuitry configured to:

measure an estimated time ta from a center of the A servo burst in a first servo frame to a center of the A servo burst in a second servo frame;

generate an A burst window for the A servo burst in a third servo frame based on the estimated time ta;

read the A servo burst in a third servo frame using the head to generate a first read signal;

sample the first read signal to generate first signal samples;

use a first matched filter matched to the A servo burst to filter the first signal samples to generate first filtered samples within the A burst window;

process the first filtered samples to generate a position error signal (PES); and

control a position of the head relative to the magnetic media based on the PES.

11. The data storage device as recited in claim 10 , wherein each servo burst comprises a plurality of servo stripes.

12. The data storage device as recited in claim 10 , wherein the data storage device further comprises the magnetic media, and the magnetic media includes magnetic tape.

13. The data storage device as recited in claim 10 , wherein:

the magnetic media is housed in a cartridge assembly; and

the data storage device further comprises a tape drive assembly configured to receive the cartridge assembly.

14. The data storage device as recited in claim 10 , wherein the control circuitry is further configured to:

generate a C burst window based on the estimated time ta;

read the C servo burst in the first servo frame using the head to generate a second read signal;

sample the second read signal to generate second signal samples;

use a second matched filter matched to the C servo burst to filter the second signal samples to generate second filtered samples within the C burst window; and

process the second filtered samples to generate the PES.

15. The data storage device as recited in claim 14 , wherein the control circuitry is further configured to generate the C burst window based on a predetermined fraction of the estimated time ta.

16. A data storage device configured to access a magnetic media comprising a plurality of servo frames each comprising an A servo burst, a B servo burst, a C servo burst, and a D servo burst, the data storage device comprising:

at least one head configured to access the magnetic media; and

a means for reading the A servo burst in a first servo frame using the head to generate a first read signal;

a means for sampling the first read signal to generate first signal samples;

a means for using a first matched filter matched to the A servo burst to filter the first signal samples to generate first filtered samples within a first burst window;

a means for first updating the first burst window based on the first filtered samples;

a means for processing the first filtered samples within the first burst window to generate a position error signal (PES); and

a means for controlling a position of the head relative to the magnetic media based on the PES.

17. The data storage device as recited in claim 16 , wherein the data storage device further comprises the magnetic media, and the magnetic media includes magnetic tape.

18. The data storage device as recited in claim 16 , wherein:

the magnetic media is housed in a cartridge assembly; and

the data storage device further comprises a tape drive assembly configured to receive the cartridge assembly.

19. The data storage device as recited in claim 16 , wherein the first burst window estimates a center of the A servo burst in the first servo frame, and the data storage device further comprises:

a means for reading the A servo burst in a second servo frame using the head to generate a second read signal;

a means for sampling the second read signal to generate second signal samples;

a means for using the first matched filter to filter the second signal samples to generate second filtered samples within the first updated first burst window; and

a means for second updating the first burst window based on the second filtered samples.

20. The data storage device as recited in claim 19 , further comprising:

a means for measuring an A-A burst interval representing an estimated time ta from the center of the A servo burst in the first servo frame to a center of the A servo burst in the second servo frame; and

a means for second updating the first burst window based on the estimated time ta.

21. The data storage device as recited in claim 20 , further comprising:

a means for generating a second burst window based on the estimated time ta;

a means for reading the C servo burst in the first servo frame using the head to generate a third read signal;

a means for sampling the third read signal to generate third signal samples;

a means for using a second matched filter matched to the C servo burst to filter the third signal samples to generate third filtered samples within the second burst window; and

a means for processing the third filtered samples to generate the PES.

22. The data storage device as recited in claim 21 , further comprising a means for generating the second burst window based on a predetermined fraction of the estimated time ta.