Patent ID: 8111474

Claim:
A magnetic storage apparatus comprising: a reproducing head configured to reproduce information from a perpendicular magnetic recording medium that is recorded with servo information, eccentricity correction data and read/write data; a synchronizing circuit; a filter part configured to filter a reproduced output of the reproducing head, by filtering the servo information which has a differentiated waveform by a non-differentiating filter characteristic, and by filtering the eccentricity correction data and the read/write data which have rectangular waveforms by a differentiating filter characteristic; a demodulating part configured to demodulate the servo information, the eccentricity correction data and the read/write data that are filtered by the filter part; a servo system configured to carry out a control process including an eccentricity control based on the servo information and the eccentricity correction data that are demodulated; and a data processing system configured to process the read/write data that are demodulated; wherein the perpendicular magnetic recording medium comprises a servo region and a data region, the servo region is recorded with a first preamble, the servo information, a second preamble and the eccentricity correction data, and the data region is recorded with a third preamble and the read/write data: the synchronizing circuit is configured to generate first through third clocks and a servo mark from patterns of the first through third preambles having a constant period and mutually different frequencies, from the reproduced output of the reproducing head, and the filter part is configured to filter the reproduced output by the non-differentiating filter characteristic while reading the first preamble, the servo mark, and a servo burst within the servo region, based on the first clock and the servo mark, and to filter the reproduced output by the differentiating filter characteristic while reading the second preamble and the eccentricity correction data within the servo region and the third preamble and the read/write data within the data region, based on the second clock and the servo mark.