Read channel processor
Adapting a read channel processor is disclosed. Adapting includes determining a target output for input data from a variable target function, determining a filter output corresponding to the input data from a programmable filter having programmable filter coefficients, comparing the target output and the filter output, and recursively updating both the variable target function and the programmable filter coefficients to improve the comparison between the target output and the filter output.
1. A method of adapting a read channel processor, including:
determining a target output from a variable target function when a known sequence is provided as input to the variable target function;
determining a filter output from a programmable filter having programmable filter coefficients when a received sequence is provided as input to the programmable target function;
comparing the target output and the filter output, wherein comparing is performed by a processor; and
recursively updating both the variable target function and the programmable filter coefficients to improve the comparison between the target output and the filter output.
2. A method as recited in claim 1 , wherein the programmable filter is an FIR filter.
3. A method as recited in claim 1 , wherein recursively updating includes updating at least one programmable filter coefficient.
4. A method as recited in claim 1 , wherein recursively updating includes updating at least one target function coefficient.
5. A method as recited in claim 1 , wherein recursively updating includes determining whether an error criterion is reached.
6. A method as recited in claim 1 , wherein an improved comparison includes a lower mean squared error between the target output and the filter output.
7. A method as recited in claim 1 , wherein recursively updating includes determining whether a certain mean squared error has been reached.
8. A method as recited in claim 1 , wherein recursively updating includes using a recursive optimization method.
9. A method as recited in claim 1 , wherein recursively updating includes using a least mean squares (LMS) method.
10. A method as recited in claim 1 , wherein updating is performed during manufacture.
11. A method as recited in claim 1 , wherein updating is performed online.
12. A method as recited in claim 1 , further including automatically determining whether updating needs to be performed.
13. A method as recited in claim 1 , further including adaptively generating a sampling clock without a contribution from the programmable filter.
14. A method as recited in claim 1 , further including determining a sampling phase such that the sampling occurs substantially on a side of an expected signal waveform corresponding to the input data.
15. A method as recited in claim 1 , wherein the processor is selectably coupled to a plurality of channel models.
16. A system for adapting a read channel processor, including:
a processor configured to:
determine a target output from a variable target function when a known sequence is provided as input to the variable target function;
determine a filter output from a programmable filter having programmable filter coefficients when a received sequence is provided as input to the programmable target function;
compare the target output and the filter output; and
recursively update both the variable target function and the programmable filter coefficients to improve the comparison between the target output and the filter output; and
a memory coupled with the processor, wherein the memory provides the processor with instructions.
17. A system as recited in claim 16 , wherein the processor is configured to recursively update at least in part by updating at least one programmable filter coefficient.
18. A system as recited in claim 16 , wherein the processor is configured to recursively update at least in part by updating at least one target function coefficient.
19. A system as recited in claim 16 , wherein the processor is configured to recursively update at least in part by using a recursive optimization method.
20. A computer program product for adapting a read channel processor, the computer program product being embodied in a computer readable storage medium and comprising computer instructions for:
determining a target output from a variable target function when a known sequence is provided as input to the variable target function;
determining a filter output from a programmable filter having programmable filter coefficients when a received sequence is provided as input to the programmable target function;
comparing the target output and the filter output; and
recursively updating both the variable target function and the programmable filter coefficients to improve the comparison between the target output and the filter output.
21. A computer program product as recited in claim 20 , wherein recursively updating includes updating at least one programmable filter coefficient.
22. A computer program product as recited in claim 20 , wherein recursively updating includes updating at least one target function coefficient.
23. A computer program product as recited in claim 20 , wherein recursively updating includes using a recursive optimization method.