Method and apparatus for determining the tribology for a head/disk interface
AssigneeHitachi Global Storage Technologies Netherlands B.V.
InventorsHal Hjalmar Ottesen, Gordon James Smith
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Abstract
A method and apparatus are provided for determining the tribology for a head/disk interface in a direct access storage device (DASD). A readback signal is obtained from a predetermined cylinder. The readback signal is sampled to provide a readback sampled sequence. The readback sampled sequence is summed to store a sum for each data sector of a plurality of data sectors in said predetermined cylinder. Predetermined discrete Fourier transform (DFT) magnitude components are calculated for the data sector sums. A harmonic ratio is calculated utilizing the calculated predetermined DFT magnitude components. The calculated harmonic ratio is compared with a predefined threshold value to identify the tribology for a head/disk interface.
Claims20
A method for determining the tribology for a head/disk interface in a direct access storage device (DASD) comprising the steps of:
- obtaining a readback signal from a predetermined cylinder;
- sampling said readback signal to provide a readback sampled sequence;
- summing said readback sampled sequence to store a sum for each data sector of a plurality of data sectors in said predetermined cylinder;
- calculating predetermined discrete Fourier transform (DFT) magnitude components for said data sector sums;
- calculating a harmonic magnitude ratio utilizing said calculated predetermined DFT magnitude components;
- and
- comparing said calculated harmonic magnitude ratio with a predefined threshold value to identify the tribology for a head/disk interface.
Apparatus for determining the tribology for a head/disk interface in a direct access storage device (DASD) comprising:
- a head for obtaining a readback signal from a predetermined cylinder of a data surface;
- an analog-to-digital for sampling said readback signal to provide a readback sampled sequence;
- an accumulator for summing said readback sampled sequence to store a sum for each data sector of a plurality of data sectors in said predetermined cylinder;
- a discrete Fourier transform (DFT) calculator for calculating predetermined discrete Fourier transform (DFT) magnitude components for said data sector sums;
- a ratio calculator for calculating a harmonic ratio utilizing said calculated predetermined DFT magnitude components;
- and
- a decision block for comparing said calculated harmonic ratio with a predefined threshold value to identify the tribology for a head/disk interface.
Dependencies are inferred from the claim text.