Adaptive maximum a posteriori (MAP) detector in read channel

A method comprising:

• receiving input sample data;
• equalizing the received sample data to yield equalized sample data;
• filtering noise in the equalized sample data;
• and
• performing iterative data detection, using a detector, on the filtered equalized sample data to yield a multi-tap partial response target;
• programming a branch metric, a variance, and a scaling factor for equalizer adaptation during a global iteration of the detector;
• delaying the equalized sample data yielded by the equalizer;
• comparing the delayed equalized sample data to the multi-tap partial response target;
• and
• performing tap adaptation based upon the comparison of the delayed equalized sample data to the multi-tap partial response target.

A storage system, comprising:

• a storage medium configured to maintain a data set;
• a read/write assembly operable to read the data set on the storage medium;
• and
• a read channel having a data processing apparatus operable to correct errors in the data set read from the storage medium, comprising:
• an analog front end configured to receive and process an analog signal from the read/write assembly to yield sample data;
• an equalizer configured to receive the sample data yielded by the analog front end, the equalizer configured to equalize the sample data to yield equalized sample data;
• a noise predictive filter configured to receive the equalized sample data yielded by the equalizer, the filter operable to filter noise in the equalized sample data;
• a detector configured to perform iterative data detection on the filtered equalized sample data, the detector operable to program a branch metric, a variance, and a scaling factor for equalizer adaptation during a global iteration of the detector, the detector configured to yield a multi-tap partial response target;
• delay circuitry configured to receive and delay the equalized sample data yielded by the equalizer;
• a comparator configured to receive the delayed equalized sample data yielded by the delay circuitry and the multi-tap partial response target yielded by the detector, the comparator configured to compare the delayed equalized sample data to the multi-tap partial response target, the output of the comparator coupled with the equalizer for tap adaptation;
• and
• a timing loop coupled with the output of the comparator and configured to control timing of the analog front end based upon the comparison of the delayed equalized sample data to the multi-tap partial response target.