Seagate Technology Incorporated

Edmun Chian Song Seng

Utt Heng Kan

Lin Nah Lim

Det Hau Wu

Jose Mari Corral Toribio

Meng Suan June Lee

Luh Chyuan Lau

Xiong Liu

UttHeng Kan

Choon Kiat Lim

Aik Chuan Lim

Kay Hee Tang

A method involves determining bit aspect ratios for interlaced tracks written to a magnetic recording medium. The interlaced tracks include top tracks that are written partially overlapping with bottom tracks. Isolated test tracks are written at first different bit aspect ratios to determine a top bit aspect ratio that achieves a first target areal density for the isolated test tracks. Test tracks are written at second different bit aspect ratios to determine a bottom bit aspect ratio that achieves a second target areal density for the test tracks. Top test tracks of the test tracks are written at the top bit aspect ratio. The top and bottom bit aspect ratios are selected to subsequently write partially-overlapping tracks on the magnetic recording medium.

Determining bit aspect ratios for partially-overlapping magnetic recording tracks

A method involves determining bit aspect ratios for interlaced tracks written to a magnetic recording medium. The interlaced tracks include top tracks that are written partially overlapping and interlaced with bottom tracks. Isolated test tracks are written at first different bit aspect ratios to determine a top bit aspect ratio that achieves a first target areal density for the isolated test tracks. Interlaced test tracks are written at second different bit aspect ratios to determine a bottom bit aspect ratio that achieves a second target areal density for the interlaced test tracks. Top test tracks of the interlaced test tracks are written at the top bit aspect ratio. The top and bottom bit aspect ratios are selected to subsequently write interlaced tracks on the magnetic recording medium.

Determining bit aspect ratios for interlaced magnetic recording tracks

The thermal decay of data written to a magnetic mass storage medium is determined by measuring and analyzing the time-domain equalized-signal-to-noise ratio (ESNR) and equalized signal-to-total-distortion noise ratio (ESTDR) of written data. In some embodiments, a test track and a reference track are initialized from data. Subsequently, the reference track is re-initialized from the test data, and the time-domain ESNR and/or ESTDR measurements are made of the test track and the reference track, at predetermined time intervals. Later, the time-domain ESNR and ESTDR measurements are analyzed to determine the thermal decay of the data written. In another embodiment of the present invention, the ESNR and/or ESTDR measurements includes reading the data through a non-return-to-zero bus in phases, in which the phases are selected in sequence.

Systems, apparatus, and methods to determine thermal decay characterization from an equalized signal-to-noise ratio of a magnetic disc drive device

A method of and apparatus for generating a reader-to-writer offset for a head positioned over a track on a disc in a disc drive having a plurality of tracks is disclosed. A reader and a writer are mounted on the head in a non-overlapping manner with a gap between the reader and the writer, which is known as the reader-to-writer offset. A disc drive controller is operably connected to the reader and the writer. The disc drive controller determines the reader-to-writer offset of the head for each track by computing the difference between a first head position x1 and a second head position x2. The first head position x1 is an optimal head position for writing information on the track and the second head position x2 is a midpoint of an off-track capability (OTC) of the head. The OTC is a portion of a track pitch over which the reader is expected to read information that is free of an incorrigible bit error such that the writer-to-reader track misregistration (TMR) is minimized as the head is radially displaced the reader-to-writer offset to read information written on the track or to write information on the track.

Optimal reader-to-writer offset measurement of a head in a disc drive for reduced track misregistration

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Singapore, Singapore

Edmun Chian Song Seng