Initialization and calibration of magnetic tape having multiple servo areas

An apparatus for initializing a bi-directional, multi-track magnetic tape drive having multiple, spaced-apart, longitudinal servo elements, comprising:

• a magnetic tape head having left and right modules, each of said modules having an upper group of servo read elements vertically interleaved with a lower group of servo read elements, each of said upper and lower groups of each of said left and right modules having a number of servo elements corresponding to the number of servo areas on a removable magnetic tape, said servo elements of each of said upper and lower groups of said left module being horizontally aligned with corresponding servo elements of each of said upper and lower groups, respectively, of said right module, each said servo element capable of generating an unadjusted position error signal representative of a position of said servo element relative to a selected one of an upper edge and a lower edge of one of the servo areas on the tape;
• servo control means for moving said head among a first plurality of index positions and, after moving said head to a desired one of said index positions, moving said head in small increments about said desired index position whereby a predetermined position of at least one of said servo elements in a selected one of said upper and lower groups of a selected one of said left and right modules follows a selected one of the upper and lower edges of a corresponding servo area during a tape access operation;
• and
• a control unit, interconnected with said tape head and said servo control means, for determining element-to-element, module-to-module and azmuthal offsets in each of said servo elements each time a magnetic tape is mounted in the tape drive and, during data read operations, for generating an adjusted position error signal for each active servo element during data read operations based upon the unadjusted position error signals and the determined offsets and directing said servo control means in accordance with the adjusted position error signals, said control unit comprising:
• means for measuring individual average position error signals AvgPES(C,D,E,G,M) generated by said servo elements, where:
• C specifies a selected servo area;
• D specifies a selected direction of the tape;
• E specifies a selected servo area edge;
• G specifies a selected group;
• and M defines a selected module;
• means for calculating group average position error signals GroupAvg(D,E,G,M) from the individual average position error signals;
• means for calculating module-to-module average position error signals ModModAvg(D) from the group average position error signals;
• means for calculating read offsets ReadOffset(C,D,E,G,M) from the individual average position error signals and the group average position error signals;
• a first memory for storing the calculated read offsets for the mounted magnetic tape;
• and
• means for calculating an adjusted position error signal AdjPES(C,D,E,G,M) for each active servo element from measured position error signals and the stored read offsets during data read operations on the mounted magnetic tape.