One illustrative embodiment of the present invention pertains to a device. The device is configured to evaluate a Gray code value and to provide compensation for error in the Gray code value. Another illustrative embodiment of the present invention pertains to a method. The method includes comparing Gray code information with servo information. The method also includes evaluating error in the Gray code information based on the comparison between the Gray code information with servo information. Another illustrative embodiment of the present invention pertains to a data storage system. The data storage system includes a data storage medium, a head, and a controller. The head is controllably positionable relative to the data storage medium. The controller includes a means for sensing position information from the head. The controller also includes a means for compensating for error in the position information, to position the head relative to the data storage medium. Embodiments of the present invention provide unforeseen and inventive advantages over conventional data storage systems, including by assuring superior position evaluation and control of a read head relative to a data storage medium.