Characterization of three servo patterns for position error signal generation in hard drives

Servo writing is an expensive and time-consuming process for formatting hard disk drives. Research efforts are investigating preformatting as a cost effective alternative. However, preformatting and servo writing differ considerably in dimensional accuracy, which affects position error signal (PES) quality and servo tracking. Selecting the best PES generation method for preformatted media is challenging because the dimensional characteristics affects each method differently. This paper discusses three methods for generating PESs -comparing performance and sensitivity to dimensional variations and electronics noise. The paper compares both analog and digital demodulation and focuses on determining which method is best suited for preformatted media.