Apparatus for reading and/or writing information from/onto an optical data carrier

Abstract

An apparatus in accordance with the invention for reading and/or writing information from/onto an optical data carrier ( ) has a transducer ( ) for generating a detection signal (S ) in response to a signal (x) recorded on the data carrier. The apparatus has correction unit ( ) for reducing errors in the detection signal (S ) as a result of radial tilt. The apparatus further has error signal generating unit ( ) for generating an error signal (S ) for the correction unit ( ). The error signal generating unit ( ) calculate the error signal (S ) from correlations between a first auxiliary signal (S ) and a second auxiliary signal (S ) and from correlations between the first auxiliary signal (S ) and a third auxiliary signal (S ), which auxiliary signals are derived from the detection signal (S ). The second (S ) and the third auxiliary signal (S ) are estimates of the recorded signal (x). The first and the third auxiliary signal (S ,S ) respectively have a first delay and a second delay (T) with respect to the second auxiliary signal (S ), the magnitude of the delays corresponding respectively to the duration of one revolution and two revolutions of the data carrier.