Marvell International Limited

Alex Chiang

Yuan Zheng

Enya Cheng

Aspects of the disclosure provide a method for calibrating gains of an optical storage servo system having a plant. The method includes translating a first signal of the plant from a time domain effort signal into a frequency domain effort signal, translating a second signal of the plant from a time domain error signal into a frequency domain error signal, determining a first gain of the optical storage servo system based on the first signal and the second signal, comparing a third signal from an optical disk of the optical storage servo system with a predetermined threshold, and asserting a defect flag when the third signal drops below the predetermined threshold to avoid calibrating the first gain based on the first signal and the second signal.

Plant gain calibration for an optical storage servo system

A gain calibration method for optical storage servo systems in which, plant gain calibration is used by injecting a reference sine wave r into an optical storage servo system, obtaining an effort signal m at the input of the servo plant and an error signal y at the output of the servo plant, using a DFT (Discrete Fourier Transformation) to translate the time domain signals m and y into frequency responses M and Y, calculating a Y-to-M ratio, and using the magnitude of the Y-to-M ratio as the plant gain K of the servo system. The servo system's sensor gain Kat the outermost layer of a disk may be calibrated by, e.g., the conventional peak-to-peak measurement. Since K=K&#xb7;K, the servo system's actuator gain Kat the outermost layer of the disk may be obtained. Because the actuator gain Kis the same for all layers of a disk, the variation of the sensor gain Kat an inner layer may follow that of the plant gain K at that layer. Accordingly, the sensor gain Kmay be calibrated for each layer of a multilayer disk, and the calibration is independent from the compensator C.

A gain calibration method for optical storage servo systems in which, plant gain calibration is used by injecting a reference sine wave r into an optical storage servo system, obtaining an effort signal m at the input of the servo plant and an error signal y at the output of the servo plant, using a DFT (Discrete Fourier Transformation) to translate the time domain signals m and y into frequency responses M and Y, calculating a Y-to-M ratio, and using the magnitude of the Y-to-M ratio as the plant gain K of the servo system. The servo system's sensor gain K1 at the outermost layer of a disk may be calibrated by, e.g., the conventional peak-to-peak measurement. Since K=K1&#xb7;K2, the servo system's actuator gain K2 at the outermost layer of the disk may be obtained. Because the actuator gain K2 is the same for all layers of a disk, the variation of the sensor gain K1 at an inner layer may follow that of the plant gain K at that layer. Accordingly, the sensor gain K1 may be calibrated for each layer of a multilayer disk, and the calibration is independent from the compensator C.

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Taipei, Taiwan

Alex Chiang