Evaluation of track following servo performance for patterned servo sectors in hard disk drives

— A promising approach for ultra high data storage capacities in magnetic hard disk drives is the use of bitpatterned media (BPM) that allows both higher track densities and increased linear bit spacing of data. To allow for such ultra high track densities, it is important to select an embedded servo pattern within the BPM that provides a Position Error Signal (PES) with sufficient quality to maintain (high bandwidth) head positioning. This paper discusses servo pattern performance from a closed-loop point of view for several servo patterns that could be incorporated in a BPM. A dedicated magnetic readback signal simulation and signal decoding along with a closed-loop simulation are used to evaluate tracking and PES quality. Due to PES nonlinearity in the conventional amplitude based servo pattern currently used in most drives, a timing based chevron pattern and a differential frequency pattern are considered as case studies in this paper. For the timing based servo patterns, both r...

• Type: Conference
• Year: 2009
• Where: CDC
• Authors: Younghee Han, Raymond A. de Callafon
• Keywords: Amplitude Based Servo, CDC 2009, Control Systems, Embedded Servo Pattern, Servo Patterns