Patent ID: 6956709

Claim:
A tape drive for use with magnetic tapes of the type in which, during writing, a tape transport velocity is matched to a composite transfer rate of a host computer and wherein a write channel transfer function varies as a result, the tape drive comprising: a housing for receiving a magnetic tape having a track; a tape head for reading and writing the track of the magnetic tape, wherein reading the track produces a data signal; a processing circuit including a partial response maximum likelihood (PRML) equalization/detection channel for processing the data signal to determine the data stream for the data signal; wherein the processing circuit is configured to, when the track is being read, process a lead-in code of the data signal prior to determining the data stream, the lead-in code identifying a velocity with which the track data were written, the processing circuit being further configured to adjust the equalization/detection channel based on the identified velocity to compensate for write channel transfer function variation; and wherein the lead-in code is coded in a way that is reasonably immune to write channel transfer function variation such that the lead-in code is comprehended by the processing circuit prior to adjusting the equalization/detection channel.