Patent ID: 8611039

Claim:
A decoder apparatus to decode longitudinal position (LPOS) information from servo elements arranged in a longitudinally extending sequence in servo bursts on a data storage medium, at least some of the servo bursts including non-shifted elements and an unbroken sequence of plural shifted elements, variations in the relative displacement of the non-shifted and shifted elements within a servo burst encoding the LPOS information, the decoder apparatus comprising: a detector to receive signals from a transducer head apparatus that detects the servo elements as they move past the transducer head apparatus; a processor to: process information produced from the signals to obtain data related to relative displacement of mutually adjacent shifted and non-shifted elements within respective ones of the servo bursts, and data related to relative displacement of mutually non-adjacent shifted and non-shifted elements within the respective ones of the servo bursts; and process the data to determine LPOS bit values corresponding to respective ones of the servo bursts.