ADDITIONAL DATA CHANNEL IN PREGROOVE

摘要

A record carrier is described for recording information by writing marks in a track. The record carrier has a pregroove (14) indicating the position of the track. The pregroove exhibits a wobble and in addition thereto a pregroove modulation (13) constituted by variations of a physical parameter related to the shape of the pregroove, e.g. width or depth. The marks are detectable during scanning the track via a beam of radiation by a first type of variations of the radiation, e.g. by changes of reflected radiation. The pregroove modulation (13) is also detectable by variations of said first type, whereas the wobble is detectable during said scanning by a second type of variations of the radiation.