Dynamic measurement of head media spacing modulation
AssigneeSeagate Technology LLC
InventorsHuazhou Lou, Zine-Eddine Boutaghou
Life of this patent
Estimating the term…
Abstract
The present invention is a novel method and apparatus for determining head media modulation in a magnetic data storage and retrieval system. The magnetic data storage and retrieval system includes a magnetic disc with a stored signal and a transducing head for reading a readback signal based on the stored data. The system includes a data acquisition and processing circuit. The processing circuit generates a dynamic harmonic ratio for the readback signal. The processing circuit also generates a head media modulation signal as a function of time from the dynamic harmonic ratio.
Claims20
A magnetic data storage and retrieval system comprising:
- a rotatable magnetic disc having a readback signal stored over a section of the magnetic disc;
- a transducing head for reading the readback signal from the magnetic disc, the transducing head being positioned to fly at a fly height with respect to the magnetic disc when the magnetic disc is rotated;
- means for processing the readback signal to calculate a dynamic harmonic ratio as a function of time;
- and
- means for calculating head media modulation as a function of time from the dynamic harmonic ratio.
A magnetic data storage and retrieval system comprising:
- a rotatable magnetic disc having data stored therein;
- a transducing head for reading a readback signal representative of the data from the magnetic disc as the transducing head is flying above the magnetic disc as the magnetic disc is rotated;
- a data acquisition circuit for digitizing the readback signal;
- and
- a processing circuit for (a) calculating a frequency spectrum of the readback signal for each of multiple selected sampling intervals of the readback signal, (b) calculating a harmonic ratio for each of the selected sampling intervals based on the calculated frequency spectrum for each of the selected sampling intervals, (c) generating a dynamic harmonic ratio for the readback signal from the harmonic ratio calculations, and (d) generating a head media modulation signal as a function of time from the dynamic harmonic ratio.
A method for determining a dynamic harmonic ratio for an entire readback signal in a data storage and retrieval system comprising:
- rotating a magnetic disc having a readback signal stored therein;
- reading the readback signal from the magnetic disc with a transducing head being positioned above the magnetic disc when the magnetic disc is rotated;
- storing the readback signal;
- calculating a frequency spectrum of the readback signal for each of multiple selected sampling intervals of the readback signal;
- calculating a harmonic ratio for each of the selected sampling intervals based on the calculated frequency spectrum for each of the selected sampling intervals;
- and
- generating a dynamic harmonic ratio for the readback signal from the harmonic ratio calculations;
- and
- generating a head media modulation signal as a function of time from the dynamic harmonic ratio.
Dependencies are inferred from the claim text.