US 6,646,964 B1 · Harmonic correction in phase-locked loops

Abstract

Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Claims4

Dependent claims

A removable media disk drive comprising:

reading means for reading a signal from the media,
a phase-locked loop connected to the means for reading, the phase locked-loop recovering a reference signal from the signal on the media, and
a harmonic corrector for reducing the effects of harmonic disturbance on the phase-locked loop, wherein the harmonic corrector comprises a notch filter connected between the reading means and the phase-locked loop, the notch filter filtering desired harmonic content.

Dependencies are inferred from the claim text.

Facts

Application

09/536,298Filed 27 Mar 2000

Granted

11 Nov 2003

Term ends

Not estimatedThe source records don’t support an estimate.

Classification12 codes

H03L 7/087
Concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal: using at least two…
G11B 5/59627
For track following on disks: aligning for runout, eccentricity or offset compensation
G11B 7/0941
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
G11B 7/0953
Specially adapted for discs, e.g. for compensation of eccentricity or wobble: to compensate for eccentricity of the disc or disc tracks

Harmonic correction in phase-locked loops

Life of this patent

Harmonic correction in phase-locked loops

Life of this patent

Abstract

Claims4