Patent ID: 7006311

Claim:
A disk drive system, comprising: a head disk assembly including: a disk having servo wedges and data fields; and at least one head to read the servo wedges and data fields and to produce a signal representative of information stored in the servo wedges and data fields; and a path to condition the signal produced by the at least one head and to produce a conditioned signal therefrom; a servo demodulator to search for a servo address mark (SAM) pattern in the conditioned signal, the servo demodulator including a servo automatic gain controller to adjust an amplitude of the conditioned signal; a storing means for storing at least one servo automatic gain control (AGC) value for the servo automatic gain controller; and a microprocessor to characterize a detection of the SAM pattern, by the servo demodulator, as either a good SAM detection or a bad SAM detection; wherein, after a good SAM detection in a servo wedge, the microprocessor selects a stored servo AGC value corresponding to the servo wedge to use as, or to predict, a starting servo AGC value for use by the servo automatic gain controller when the at least one head begins to read a next servo wedge.