Patent ID: 8422161
Filing Date: 2013-04-16
Classification: G11B

Abstract:
1. An information storage system comprising: a disk with a plurality of prerecorded servo fields arranged in servo wedges, each servo field including at least one sequence of a plurality of encoded bits which is a member of a predetermined set of permissible sequences that includes at least four unique sequences, the sequences being arranged in patterns that encode location identifiers with an ordered set of sequences that includes at least two sequences defining an integer location identifier and the ordered set of sequences defining the location identifier being distributed across at least two servo wedges, the set of permissible sequences including sequences that are mutually mathematically orthogonal and sequences that are not mutually mathematically orthogonal and the sequences being arranged in patterns so that sequences that are adjacent in a cross-track direction are mathematically orthogonal; 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 a location identifier decoder that uses at least two sequences from at least two servo wedges detected by the filters to derive the location identifier.