Patent ID: 9177581
Filing Date: 2015-11-03
Classification: G11B

Abstract:
1. A head position demodulation method comprising: at demodulation of an A-phase burst pattern and a B-phase burst pattern arranged in a down-track direction so as to be different in phase in a cross-track direction, calculating a demodulated position of a magnetic head based on a sin component and a cos component of the A-phase burst pattern and a sin component and a cost component of the B-phase burst pattern, wherein, assuming that phase differences in the A-phase burst pattern and the B-phase burst pattern in the down-track direction are designated as Δφa and Δφb, respectively, when absolute values of Δφa and Δφb are equal, a cos component of a readback signal in the A-phase burst pattern is designated as cA and a sin component of the same as sA, a cos component of a readback signal in the B-phase burst pattern is designated as cB and a sin component of the same as sB, and sgn=+1 if Δφa/Δφb≧0 and −1 if Δφa/Δφb<0, the demodulated position of the magnetic head is calculated using coefficients ca, sa, cb, and sb based on N and Q calculated as: