A method and associated apparatus for reduction of data loss errors in
computer data tape transport applications. In tape transport devices with
moveable read heads (i.e. auto-tracking read/playback heads), by sensing
telemetry information regarding tape movement and alignment of a position
on the tape medium before the position on the tape encounters the moveable
head. Prior systems provided for such sensing only as the tape was read by
the moveable head such that compensation could be made only for subsequent
read operation. By sensing the telemetry data in advance of the tape
encountering the moveable head, the head may be adjusted in time to
encounter the misaligned tape medium compensating for the misalignment.
Similarly, telemetry data relating to the speed of the tape motion as
sensed by a channel reading a predetermined recorded sequence of bits
permits compensation for both erroneous tape speed and tape medium stretch
or contraction.