Method to apply user data for read channel training and adaptation in hard disk drive applications
Calibrating a read channel is disclosed. Previously written user data is read from an auxiliary memory. The previously written user data is processed through a plurality of write channel stages. The output of at least one of the plurality of write channel stages is compared to the output of a corresponding read channel stage to generate an error signal.
1. A system for calibrating a read channel, including:
an auxiliary memory that stores previously written user data;
a plurality of write channel stages that process the previously written user data from the auxiliary memory; and
an error processor that generates an error signal at least in part by comparing an output of at least one of the plurality of write channel stages to an output of a corresponding read channel stage, wherein the corresponding read channel stage is calibrated based at least in part on the generated error signal.
2. The system as in claim 1 , wherein the previously written user data is not constrained.
3. The system as in claim 1 , wherein the previously written user data is multiplexed with a data source including one or more pseudo-random binary sequences.
4. The system as in claim 1 , wherein the write channel stages are reused.
5. The system as in claim 1 , wherein the output of the at least one write channel stage is delayed to align it in time with the output of the corresponding read channel stage.
6. The system as in claim 1 , further including a hard disk controller configured to output the previously written user data to the write channel stages while inputting corresponding data from the read channel.
7. The system as in claim 1 , further including a hard disk controller that has a facility to output neighbor track write signal information to aid in reading a signal from a shingled magnetic recording system, and wherein the neighbor track output facility is used to output the same track as the read channel in a calibration mode.
8. The system as in claim 1 , wherein the corresponding read channel stage is trained in the field using an arbitrary sequence.
9. A method of calibrating a read channel, including:
reading previously written user data from an auxiliary memory;
processing the previously written user data through a plurality of write channel stages; and
generating an error signal at least in part by comparing an output of at least one of the plurality of write channel stages to an output of a corresponding read channel stage, wherein the corresponding read channel stage is calibrated based at least in part on the generated error signal.
10. The method as in claim 9 , wherein the previously written user data is not constrained.
11. The method as in claim 9 , wherein the previously written user data is multiplexed with a data source including one or more pseudo-random binary sequences.
12. The method as in claim 9 , wherein the output of the at least one write channel stage is delayed to align it in time with the output of the corresponding read channel stage.
13. The method as in claim 9 , further including outputting the previously written user data to the write channel stages while inputting corresponding data from the read channel.
14. The method as in claim 9 , wherein the corresponding read channel stage is trained in the field using an arbitrary sequence.
15. A computer program product for calibrating a read channel, the computer program product being embodied in a non-transitory tangible computer readable storage medium and comprising computer instructions for:
reading previously written user data from an auxiliary memory;
processing the previously written user data through a plurality of write channel stages; and
generating an error signal at least in part by comparing an output of at least one of the plurality of write channel stages to an output of a corresponding read channel stage, wherein the corresponding read channel stage is calibrated based at least in part on the generated error signal.
16. The computer program product as recited in claim 15 , wherein the previously written user data is not constrained.
17. The computer program product as recited in claim 15 , wherein the previously written user data is multiplexed with a data source including one or more pseudo-random binary sequences.
18. The computer program product as recited in claim 15 , wherein the output of the at least one write channel stage is delayed to align it in time with the output of the corresponding read channel stage.
19. The computer program product as recited in claim 15 , further including outputting the previously written user data to the write channel stages while inputting corresponding data from the read channel.
20. The computer program product as recited in claim 15 , wherein the corresponding read channel stage is trained in the field using an arbitrary sequence.