Method and apparatus for analyzing tracking error in magnetic tapes

A method for distinguishing rotational from non-rotational errors in the measured tracks of a magnetic tape, said tape having a longitudinal axis, said tape interacting with a rotating head wheel having n heads angularly spaced along the circumference of said head wheel, each of said n heads inscribing one of said tracks on said tape as said head wheel is moved through one cycle of rotation, adjacent heads on said head wheel inscribing adjacent tracks on said tape, a set of n sequential tracks on said tape defining said one cycle, the spatial relationship between said tracks being measurable by reference to corresponding fixed locations within each of said tracks, and wherein the sum of rotational errors in said set of n sequential tracks is generally equal to zero and the difference between said non-rotational errors in any two adjacent tracks is generally equal to zero, comprising the steps of:

• (1) treating said tape for identifying measurement points along said tracks;
• (2) determining corrected distances between corresponding ones of said points on all of n sequential tracks along a straight line intersecting said n tracks;
• (3) determining the nominal distance between said corresponding ones of said points on all of said n sequential tracks along said straight line;
• and
• (4) comparing said corrected distances with said nominal distance to distinguish said rotational error from said non-rotational error.