Information storage device with multiple-use fields in servo pattern

An information storage system comprising:

• a disk with a plurality of prerecorded servo fields, each servo field including at least one sequence which is a member of a predetermined set of sequences in which each sequence consists of a plurality of encoded bits, the sequences being arranged in patterns that define concentric tracks and form sequence combinations that provide digital positional information;
• a read head which generates a signal created by the sequences passing under the read head when the disk is rotating;
• and
• a servo system comprising:
• a set of filters that includes a corresponding filter for detecting each sequence in the set of sequences in the signal;
• and
• comprises means for generating a servo track mark signal using output from the set of filters.

An information storage system comprising:

• a disk with a plurality of prerecorded servo fields, each servo field including at least one sequence which is a member of a predetermined set of sequences in which each sequence consists of a plurality of encoded bits, the sequences being arranged in patterns that encode location identifiers;
• a read head which generates a signal created by the sequences passing under the read head when the disk is rotating;
• and
• a servo system comprising:
• a set of filters that includes a corresponding filter for detecting each sequence in the set of sequences in the signal;
• means for detecting first and second signal amplitudes corresponding to first and second sequences in the signal to generate a position error signal to position the read head over a selected data track;
• a location identifier decoder that uses at least two sequences detected by the filters to derive the location identifier;
• and
• a servo track mark signal detector that uses sequences detected by the filters.