Record carrier with variations of different physical parameters thereof in different frequency bands during recording

摘要

A record carrier on which information is recorded in the form of first variations caused by the presence or absence of information marks along a recording track, such variations representing an information signal. The record carrier also exhibits second variations in the form of changes in the position of the information marks in a direction transversed to the track direction. The second variations having a frequency spectrum substantially entirely outside the frequency spectrum of the first variations. The second variations are detectable by the same playback transducer which detects the first variations, and the presence of the second variations may be necessary to enable the transducer to detect the first variations.