Patent ID: 7876521

Claim:
Servo apparatus for a tape drive having a read/write head for reading and writing data on magnetic tape having at least one servo track for providing transverse position information, the servo apparatus comprising: at least two servo readers associated with the read/write head, each servo reader being arranged for reading said at least one servo track during read/write operations, the servo readers being operative concurrently to generate respective servo read signals; a position estimator for processing each servo read signal to generate a series of position values each corresponding to a respective time instant, the position values being indicative of transverse position of the associated servo reader; and a servo controller for calculating from said position values and time instants (i) a skew value indicative of tape skew relative to the read/write head and (ii) a tension variation value indicative of variation of tape tension from a reference value; wherein said servo controller is adapted to account for cross-coupling between tape skew and tension variation in calculating the skew and tension variation values.