Patent ID: 8867162

Claim:
A magnetic disk device comprising: a magnetic head; a magnetic disk comprises a burst pattern recorded thereon for determining a position of the magnetic head on a track based on a reading result by the magnetic head; and a magnetic recording controller configured to calculate a demodulation position of the magnetic head based on the burst pattern that is read and correct the calculated demodulation position based on an offset correction value subject to fluctuation of the burst pattern, wherein the offset correction value comprises an N phase offset correction value and a Q phase offset correction value, the N phase offset correction value is calculated based on an addition result of an N phase positive side output and an N phase negative side output at an off track position at which an N phase output obtained from the burst pattern comes to a peak or at an off track position at which a Q phase output is zero, and the Q phase offset correction value is calculated based on an addition result of a Q phase positive side output and a Q phase negative side output at an off track position at which a Q phase output obtained from the burst pattern comes to a peak or at an off track position at which an N phase output is zero.