Patent ID: 7289409

Claim:
An apparatus for reading and/or writing data from and/or onto a data carrier, said data carrier containing wobbled tracks, said apparatus comprising: scanning means for scanning said tracks; detection means for detecting at least two elementary signals when scanning said tracks; wobble recovery means for generating a wobble signal from said at least two elementary signals; and wobble processing means for filtering said at least two elementary signals with at least an adaptive filter and for generating an improved wobble signal by subtracting said filtered elementary signals from said wobble signal, said apparatus further comprising: data recovery means for generating a data signal from said at least two elementary signals, wherein said adaptive filter uses filtering coefficients chosen so as to minimize the cross-correlation between said improved wobble signal and said data signal, and wherein said filtering coefficients are updated by using an iterative gradient algorithm minimizing a cost function having an instantaneous value equal to the instantaneous value of the squared product of said improved wobble signal and said data signal.