Apparatus for reproducing a digital information signal from a record carrier and counting the number of bits between two sync patterns

摘要

An apparatus for reproducing a digital information signal from a record carrier includes a read unit for reading a signal from a track on the record carrier, a bit detection unit for deriving the digital information signal from the signal read from the track in response to a clock signal and a phase locked loop for deriving the clock signal from the signal read from the track. The phase locked loop includes a phase comparator for deriving a phase error signal and a voltage controlled oscillator for deriving the clock signal. The apparatus further includes a sync pattern detector for detecting sync patterns occurring in the digital information signal and a counter for counting the number of bits occurring between two sync patterns in the digital information signal. If the number of bits counted between the two sync patterns exceeds a predetermined value (THR) by at least one, at least one additional bit is inserted into the digital information signal (an insertion error) and this at least one additional bit should be deleted from the digital information in order to keep the apparatus in synchronisation. When the predetermined number exceeds the number of bits counted by at least one, at least one bit was deleted from the digital information signal (a deletion error), so that at least one bit should be added in order to keep the apparatus in synchronization.