DATA RECORD TRACKING USING TRACK IDENTIFYING INFORMATION IN THE GAPS BETWEEN RECORDED DATA GROUPS

摘要

A technique for tracking lines of recorded analog or digital data and records which can be played back using such tracking, are described in which tracking information is recorded in the gaps between groups of data on such records at positions spaced along the entire length of each track line to enable the track lines to be scanned one line at a time during readout. The tracking information includes recorded track identifying information which is distinguishable from the recorded data and which identifies a given track line from the two adjacent lines on opposite sides thereof. A time related sampling type of tracking method is described by which a light beam or other sensing means is scanned along the track lines, one line at a time, to produce an electrical readout signal corresponding to the digital data and tracking information being scanned. First and second sample signals are stored and compared to produce a correction signal corresponding to the difference between sample signals, and the correction signal is applied to a tracking means for moving the sensing means toward the center of the line being scanned by an amount proportional to the correction signal.