| US 7,492,675 B2 | ||
| Digital servo system with calibrated notch filters | ||
| Ron J. Kadlec, Longmont, Colo. (US); and Hans B. Wach, Longmont, Colo. (US) | ||
| Assigned to DPHI Acquisitions, Inc., Longmont, Colo. (US) | ||
| Filed on Sep. 10, 2001, as Appl. No. 9/950,372. | ||
| Claims priority of provisional application 60/264351, filed on Jan. 25, 2001. | ||
| Prior Publication US 2002/0131342 A1, Sep. 19, 2002 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—44.24 [369/44.39; 702/77; 700/280] | 8 Claims |
| 1. A method of calibrating a notch filter in an optical disk drive's digital servo system, comprising:
digitizing sensor signals from an optical pickup unit within the optical disk drive;
within a digital signal processor, calculating a focus error signal or a tracking error signal from versions of the digitized
sensor signals;
perturbing the digital servo system by adjusting either the focus error signal or the tracking error signal responsive to
a perturbing signal to provide an adjusted error signal;
obtaining a frequency response curve of the adjusted error signal within the digital servo system over a range of frequencies
in response to the perturbation of the digital servo system;
searching the frequency response curve for at least one frequency having a peak frequency response; and
setting notch filter parameters of the notch filter to filter signals in the digital servo system at the at least one frequency.
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