Systems and methods for adaptive gain control

A method for data processing, the method comprising:

• converting an analog input into a corresponding series of digital samples using an analog to digital converter circuit;
• applying a data detection algorithm to a data set derived from the digital samples to yield a detected output;
• convolving the detected output with a target parameter to yield a target output;
• calculating an error value as a difference between the digital samples and the target output;
• and
• updating the target parameter based at least in part on the error value, wherein updating the target parameter based at least in part on the error value includes:
• comparing an error value corresponding to a first value with an error value corresponding to a second value;
• and
• selecting the first value for the target parameter where the error value corresponding to the first value is less than the error value corresponding to the second value.

A storage device, the storage device comprising:

• a storage medium;
• a head assembly disposed in relation to the storage medium and operable to provide a sensed signal corresponding to information on the storage medium;
• a read channel circuit including:
• an analog to digital converter circuit operable to convert an analog input derived from the sensed signal into corresponding digital samples;
• a data detector circuit operable to apply a data detection algorithm to a data set derived from the digital samples to yield a detected output;
• a filter circuit operable to convolve the detected output with a target parameter to yield a target output;
• an error generation circuit operable to calculate an error value as a difference between the digital samples and the target output;
• and
• a target parameter adaptation circuit operable to update the target parameter based at least in part on the error value, wherein the target parameter adaptation circuit is operable to select a first value of the target parameter and to store the error value corresponding to the first value, and to select a second value of the target parameter and to store the error value corresponding to the second value, and wherein the target parameter adaptation circuit is further operable to compare the error value corresponding to the first value of the target parameter with the error value corresponding to the second value of the target parameter, and to select the first value for the target parameter where the error value corresponding to the first value is less than the error value corresponding to the second value.