Servoing on zoned concentric servo sectors of a first disk surface to write a spiral servo track to a second disk surface
View Patent ↗A disk drive is disclosed comprising a first head actuated over a first disk surface and a second head actuated over a second disk surface. A first servo sector of the first disk surface is read to generate a read signal which is processed to generate a first phase error. A first clock is generated at a frequency proximate a servo data rate of the first data sector. Read signal samples are synchronized in response to the first phase error and the first clock to generate synchronous samples, and servo data in the first servo sector is detected in response to the synchronous samples. The read signal is processed to generate a second phase error, a second clock is generated in response to the second phase error, and a spiral servo track is written to the second disk surface using the second clock.
1. A disk drive comprising:
a first disk surface and a second disk surface, wherein the first disk surface comprises a plurality of servo sectors defining a plurality of concentric servo tracks, wherein:
the concentric servo tracks form a plurality of servo zones; and
a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone;
a first head actuated over the first disk surface and a second head actuated over the second disk surface; and
control circuitry operable to:
read a first servo sector of the first disk surface using the first head to generate a read signal;
process the read signal to generate a first phase error;
generate a first clock at a frequency proximate the servo data rate of the first data sector;
synchronize read signal samples in response to the first phase error and the first clock to generate synchronous samples;
detect the servo data in the first servo sector in response to the synchronous samples;
process the read signal to generate a second phase error;
generate a second clock in response to the second phase error; and
write a spiral servo track to the second disk surface using the second head and the second clock.
2. The disk drive as recited in claim 1 , wherein a frequency of the second clock is substantially different than a frequency of the first clock.
3. The disk drive as recited in claim 1 , wherein the first clock is generated in response to the second clock.
4. The disk drive as recited in claim 3 , wherein the first clock is generated by scaling the second clock.
5. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:
sample the read signal to generate a plurality of sample values; and
generate the first phase error based on a difference between one of the sample values and an expected value.
6. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:
detect a sync mark in the first servo sector; and
generate the second phase error in response to the detected sync mark.
7. The disk drive as recited in claim 6 , wherein the control circuitry is further operable to:
clock a counter with the second clock; and
generate the second phase error based on a value of the counter when the sync mark is detected.
8. The disk drive as recited in claim 7 , wherein the control circuitry is further operable to:
scale the second clock to generate a third clock;
synchronize a frequency synthesizer to the third clock, wherein the frequency synthesizer generates a fourth clock by scaling the third clock, the scaling corresponding to a servo data rate of the current servo zone; and
adjust the scaling when the first head crosses a servo zone boundary while continuing to clock the counter with the second clock.
9. The disk drive as recited in claim 8 , wherein the control circuitry is further operable:
generate a fifth clock in response to a center frequency control signal generated by the frequency synthesizer;
sample the read signal using the fifth clock; and
adjust a frequency of the fifth clock in response to the first phase error in order to generate the synchronous samples.
10. The disk drive as recited in claim 8 , wherein the control circuitry is further operable:
sample the read signal using the fourth clock to generate the read signal samples; and
interpolate the read signal samples using the first phase error in order to generate the synchronous samples.
11. A method of operating a disk drive, the disk drive comprising a first disk surface and a second disk surface, wherein the first disk surface comprises a plurality of servo sectors defining a plurality of concentric servo tracks, wherein the concentric servo tracks form a plurality of servo zones, and a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone, the disk drive further comprising a first head actuated over the first disk surface and a second head actuated over the second disk surface, the method comprising:
reading a first servo sector of the first disk surface using the first head to generate a read signal;
processing the read signal to generate a first phase error;
generating a first clock at a frequency proximate the servo data rate of the first data sector;
synchronizing read signal samples in response to the first phase error and the first clock to generate synchronous samples;
detecting the servo data in the first servo sector in response to the synchronous samples;
processing the read signal to generate a second phase error;
generating a second clock in response to the second phase error; and
writing a spiral servo track to the second disk surface using the second head and the second clock.
12. The method as recited in claim 11 , wherein a frequency of the second clock is substantially different than a frequency of the first clock.
13. The method as recited in claim 11 , wherein the first clock is generated in response to the second clock.
14. The method as recited in claim 13 , wherein the first clock is generated by scaling the second clock.
15. The method as recited in claim 11 , further comprising:
sampling the read signal to generate a plurality of sample values; and
generating the first phase error based on a difference between one of the sample values and an expected value.
16. The method as recited in claim 11 , further comprising:
detecting a sync mark in the first servo sector; and
generating the second phase error in response to the detected sync mark.
17. The method as recited in claim 16 , further comprising:
clocking a counter with the second clock; and
generating the second phase error based on a value of the counter when the sync mark is detected.
18. The method as recited in claim 17 , further comprising:
scaling the second clock to generate a third clock;
synchronizing a frequency synthesizer to the third clock, wherein the frequency synthesizer generates a fourth clock by scaling the third clock, the scaling corresponding to a servo data rate of the current servo zone; and
adjusting the scaling when the first head crosses a servo zone boundary while continuing to clock the counter with the second clock.
19. The method as recited in claim 18 , further comprising:
generating a fifth clock in response to a center frequency control signal generated by the frequency synthesizer;
sampling the read signal using the fifth clock; and
adjusting a frequency of the fifth clock in response to the first phase error in order to generate the synchronous samples.
20. The method as recited in claim 18 , further comprising:
sampling the read signal using the fourth clock to generate the read signal samples; and
interpolating the read signal samples using the first phase error in order to generate the synchronous samples.