Abstract: A fast-acting method of regenerating track crossing signals for track searches across unrecorded areas on read/write optical discs is provided. This is accomplished by comparing the in-phase and quadrature-phase track crossing signals generated by the optical pickup head when a track search is being performed. A blank signal is generated when no quadrature-phase signal transition occurs between two successive in-phase signal transitions. Fake quadrature-phase signals are continuously generated. Upon occurrence of a blank indicating signal, the fake quadrature-phase signals are immediately supplied to the track crossing counter mechanism in place of the missing quadrature-phase signals. As a result, there is no loss of track count.

Abstract: Adjustment of disc-drive pickup signals in a manner that responds dynamically to changes in such signals while in use. Adjustment is directed toward achieving an approximately symmetric (i.e., 50-50) duty cycle. A variable integration rate of symmetry error responds to fluctuations in pickup signal frequency to achieve more accurate adjustment of quadrature track crossing signals during a search operation.