Synchronizing an asynchronously detected servo signal to synchronous servo demodulation
View Patent ↗A first set of data is detected in a signal having synchronous samples and interpolated samples, wherein the first set of data is detected asynchronously as corresponding to one of the samples. A time to transmit a data-found signal is determined based on an offset between the data-detected sample and one of the synchronous samples, and the data-found signal is transmitted at the determined time to enable the synchronous processing of the synchronous samples. In one implementation, the synchronous samples correspond to a readback signal read from a data recording channel, the first set of data corresponds to servo address mark (SAM) data in a servo sector in the readback signal, and the synchronous processing is demodulation of burst data in the servo sector.
1. A method for synchronizing synchronous processing using data detected asynchronously, comprising:
(a) detecting a first set of data in a signal comprising synchronous samples and interpolated samples, wherein the first set of data is detected asynchronously as corresponding to one of the samples;
(b) determining a time to transmit a data-found signal based on an offset between the data-detected sample and one of the synchronous samples; and
(c) transmitting the data-found signal at the determined time to enable the synchronous processing of the synchronous samples.
2. The invention of claim 1 , wherein:
the synchronous samples correspond to a readback signal read from a data recording channel;
the first set of data corresponds to servo address mark (SAM) data in a servo sector in the readback signal; and
the synchronous processing is demodulation of burst data in the servo sector.
3. The invention of claim 2 , wherein:
the SAM data precedes the burst data in the servo sector by a known amount of data; and
the demodulation of the burst data is initiated a specified duration following receipt of the data-found signal, wherein the specified duration is based on the known amount of data between the SAM data and the burst data.
4. The invention of claim 1 , wherein the timing of the transmission of the data-found signal is based on whether the offset is greater than or less than a specified threshold.
5. The invention of claim 4 , wherein:
the data-found signal is transmitted right away if the offset is less than the specified threshold; and
the data-found signal is transmitted after a delay if the offset is greater than the specified threshold.
6. The invention of claim 5 , wherein the delayed transmission of the data-found signal corresponds to a subsequent synchronous sample.
7. The invention of claim 1 , wherein step (b) comprises:
(1) determining whether an n-tuple of samples corresponding to the data-detected sample includes a synchronous sample; and
(2) determining the time to transmit the data-found signal based on step (b)(1).
8. The invention of claim 7 , wherein:
the data-found signal is transmitted right away if the n-tuple include a synchronous sample; and
the data-found signal is transmitted after a delay if the n-tuple does not include a synchronous sample.
9. The invention of claim 8 , wherein the delayed transmission of the data-found signal corresponds to a subsequent synchronous sample.
10. Apparatus for synchronizing synchronous processing using data detected asynchronously, comprising:
(a) means for detecting a first set of data in a signal comprising synchronous samples and interpolated samples, wherein the first set of data is detected asynchronously as corresponding to one of the samples;
(b) means for determining a time to transmit a data-found signal based on an offset between the data-detected sample and one of the synchronous samples; and
(c) means for transmitting the data-found signal at the determined time to enable the synchronous processing of the synchronous samples.
11. The invention of claim 10 , wherein:
the synchronous samples correspond to a readback signal read from a recording data channel;
the first set of data corresponds to SAM data in a servo sector in the readback signal;
the synchronous processing is demodulation of burst data in the servo sector;
the SAM data precedes the burst data in the servo sector by a known amount of data; and
the demodulation of the burst data is initiated a specified duration following receipt of the data-found signal, wherein the specified duration is based on the known amount of data between the SAM data and the burst data.
12. A read channel component comprising:
an analog-to-digital (A/D) converter adapted to generate synchronous samples based on a signal received from a data channel;
one or more interpolators adapted to generate interpolated samples based on the synchronous samples;
an asynchronous data detector adapted to:
receive the synchronous samples and the interpolated samples;
detect a first set of data as corresponding to one of the samples;
determine a time to transmit a data-found signal based on an offset between the data-detected sample and one of the synchronous samples; and
transmit the data-found signal at the determined time; and
a synchronous processor adapted to perform synchronous processing of the synchronous samples based on receipt of the data-found signal.
13. The invention of claim 12 , wherein:
the received signal is a readback signal read from a data recording channel;
the first set of data corresponds to SAM data in a servo sector in the readback signal; and
the synchronous processor is a burst demodulator adapted to demodulate burst data in the servo sector.
14. The invention of claim 13 , wherein:
the SAM data precedes the burst data in the servo sector by a known amount of data; and
the burst demodulator is adapted to initiate demodulation of the burst data a specified duration following receipt of the data-found signal, wherein the specified duration is based on the known amount of data between the SAM data and the burst data.
15. The invention of claim 12 , wherein the timing of the transmission of the data-found signal is based on whether the offset is greater than or less than a specified threshold.
16. The invention of claim 15 , wherein:
the asynchronous data detector is adapted to transmit the data-found signal right away if the offset is less than the specified threshold; and
the asynchronous data detector is adapted to transmit the data-found signal after a delay if the offset is greater than the specified threshold.
17. The invention of claim 16 , wherein the delayed transmission of the data-found signal corresponds to a subsequent synchronous sample.
18. The invention of claim 12 , wherein the asynchronous data detector is adapted to:
(1) determine whether an n-tuple of samples corresponding to the data-detected sample includes a synchronous sample; and
(2) determine the time to transmit the data-found signal based on the determination of (1).
19. The invention of claim 18 , wherein:
the asynchronous data detector is adapted to transmit the data-found signal right away if the n-tuple includes a synchronous sample; and
the asynchronous data detector is adapted to transmit the data-found signal after a delay if the n-tuple does not include a synchronous sample.
20. The invention of claim 19 , wherein the delayed transmission of the data-found signal corresponds to a subsequent synchronous sample.