Digital servo system with loop gain calibration

  • US 6,904,007 B2
  • Filed: 09/10/2001
  • Issued: 06/07/2005
  • Est. Priority Date: 01/25/2001
  • Status: Active Grant
First Claim
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1. A method of calibrating a loop gain of a loop gain amplifier in a digital servo system, comprising:

  • receiving optical signals from an optical pick-up unit in an optical disk drive;

    closing the digital servo system with a first loop gain, the digital servo system calculating a control signal based on the optical signals;

    applying a sinusoidal disturbance at a cross-over frequency to the control signal generated by the digital servo system to form a second control signal;

    controlling a position of the optical pick-up unit with the second control signal;

    calculating a discrete Fourier transform of the sinusoidal disturbance at the cross-over frequency to form a disturbance DFT;

    calculating a discrete Fourier transform of the control signal to form a signal DFT;

    calculating a measured loop gain from a ratio of the disturbance DFT and the signal DFT; and

    calculating the loop gain from a ratio between the first loop gain and the measured loop gain.

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