Patent ID: 6697209
Filing Date: 2004-02-24
Classification: G11B

Abstract:
A helical scan recording system comprising:a scanner which rotates at a rotational speed; a tape transport for transporting the magnetic tape proximate the scanner; at least a first pair of read heads mounted on the scanner, the first pair of read heads comprising a first read head and a second read head which travel in a helical direction on the magnetic tape as at least a partial result of transport of the tape and rotation of the scanner, the first read head and the second read head respectively reading information from a first track and a second track recorded on magnetic tape; a synchronization detection system which determines a first synchronization mark detection time at which a first synchronization mark is read by the first read head from the first track and a second synchronization mark detection time at which a synchronization mark read by the second read head from the second track; a position error signal generator which develops a position error signal based upon a difference between the first synchronization mark detection time and the second synchronization mark detection time; a servo controller which uses the position error signal to develop a servo correction signal for adjusting a position of the first head relative to a width of the first track and the second head relative to the width of the second track; wherein a first distance along the helical direction between the synchronization mark read by the first read head on the first track and the synchronization mark read by the second read head on the second track is sufficiently less than a second distance by which the first head is spaced circumferentially on the scanner from the second head to render the position error signal immune to any variation in the rotational speed of the scanner; wherein the synchronization detection system comprises: a first read channel which receives a first read signal from the first read head; a second read channel which receives a second read signal from the second read head; a first deformatter connected to the first read channel, the first deformatter including a first byte clock which times on a byte basis receipt of bytes of information from the first read head, the first deformatter detecting the first synchronization mark and outputting a first synchronization mark found signal at the first synchronization mark detection time, the first synchronization mark detection time being based on the first byte clock; a second deformatter connected to the second read channel, the second deformatter including a second byte clock which times on a byte basis receipt of bytes of information from the second read head, the second deformatter detecting the second synchronization mark and outputting a second synchronization mark found signal at the second synchronization mark detection time, the second synchronization mark detection time being based on the second byte clock.