Systems and methods for acquisition phase gain modification

A method for modifying a gain feedback value, the method comprising:

• receiving a first portion of data derived from a storage medium during a tracking phase;
• receiving a second portion of data derived from the storage medium during an acquisition phase;
• applying a first variable gain amplification to the first portion of data to yield a first amplified output, wherein the variable gain amplification is governed at least in part by a first gain feedback generated based upon the first portion of data;
• converting a first analog input corresponding to the first amplified output to a first series of digital samples;
• applying a second variable gain amplification to the second portion of data to yield a second amplified output, wherein the second variable gain amplification is governed at least in part by a second gain feedback;
• converting a second analog input corresponding to the second amplified output to a second series of digital samples;
• using an acquisition phase gain modification circuit to:
• estimate an amplitude of the second series of digital samples to yield an amplitude, and calculate a gain correction based at least in part on the amplitude;
• and
• correcting the second series of digital samples using the gain correction to yield corrected samples.

A storage device, the storage device comprising:

• a head including a read sensor disposable over a storage medium and operable to sense information on the storage medium and provide a corresponding sensed signal;
• a variable gain amplifier circuit operable to amplify an input signal derived from the sensed signal by a variable gain corresponding to a gain feedback value to yield an amplified output;
• an analog to digital converter circuit operable to convert an analog input into a series of digital samples, wherein the series of digital samples includes a preamble pattern, and wherein the analog input is derived from the amplified output;
• an amplitude estimation circuit operable to estimate an amplitude of the series of digital samples corresponding to the preamble pattern received during acquisition phase processing;
• a first comparator circuit operable to compare the amplitude with a first window threshold to yield a first result;
• a second comparator circuit operable to compare the amplitude with a second window threshold to yield a second result;
• an acquisition gain feedback calculation circuit operable to calculate a gain correction based at least in part on the first result and the second result, wherein the acquisition gain feedback calculation circuit is operable to leave the gain feedback value unchanged when the amplitude is within the first window threshold, and to modify the gain feedback value when the amplitude is outside the first window threshold;
• and
• a data correction circuit operable to correct the digital samples corresponding to the preamble pattern by an amount corresponding to the gain correction.