Servo techniques that mitigate an effect of read and write velocity variations on position error signal calculations

摘要

In general, the invention is directed to servo techniques that make use of time-based servo patterns that can substantially mitigate error in a position error signal (PES) calculation resulting from a variation in tape velocity. A servo pattern including at least three marks is written using a single pulse and a single servo head such that the spacing of the servo marks in the servo pattern is not dependent on write velocity. By measuring the time between detection of at least three servo marks in the servo pattern, a ratio of time increments can be used to factor out read tape velocity. In order to facilitate this effect, techniques for determining the relationship between a ratio of time increments and a PES signal are described. Also described are techniques for configuring a servo pattern that provides a linear relationship between a ratio of time increments and a PES signal.