Record carrier, playback apparatus and information system comprising a record carrier and a playback apparatus

Abstract

A playback apparatus (20) includes a transducer unit (20A, 20B, 20C) for scanning a record carrier (1). The transducer unit is adapted to detect first variations and second variations. The apparatus further includes a first recovery unit (22) coupled to the transducer unit for recovering a clock signal (CL) from the first variations and a second recovery unit (23) coupled to the transducer unit for recovering an information signal (S<out>) from the first variations. The apparatus further includes a detection unit (24) for detecting whether said second variations exhibit a predetermined variation pattern on the basis of at least one signal (SA) originating from said transducer unit. The detection unit (24) using said clock signal (CL) generated by the first recovery unit (22) for detection. Further an enabling unit (5) is included for enabling said second recovery unit (23) to recover the information signal (S<out>) when said detection unit detects (24) said predetermined variation pattern.

Description

[0001] This application is a divisional application of the application number "01801940.4", the filing date is "June 27, 2001", and the title of the invention is "record carrier, playback device and information system including record carrier and playback device". Background technique [0002] In USP 5 930 210 a record carrier, a playback device and an information system comprising a record carrier and a playback device are described. The record carrier described here comprises a first variation caused by the presence and absence of information marks along the track. Said first variation is representative of the information signal recorded on said record carrier. For example the information marks are in the form of pits. The record carrier further comprises a second change caused by a change associated with the information mark. The document cited above describes an embodiment in which the second change is in the form of a change in radial position. Set the information mark...

AI Technical Summary

Problems solved by technology

Since the radial flutter has a high frequency, e.g. 22.05kHz in the case of 1X playback speed, this results in a relatively large phase shift between the signals of the auxiliary detector, which interferes with the flutter signal reliable detection of

Alternatively, if the dither signal is derived from one of the signals of the auxiliary detector, it has a relatively large signal-to-noise ratio, which also prevents reliable detection of the dither signal

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