Digital processing of position error signal in hard disk drives

The hard disk drive (HDD) industry continues to meet the ever growing demand for storage capacity by increasing both the number of tracks on the disk surface and the number of bits recorded per track. Sensing of the position error signal (PES) plays a very important role in the precision and accuracy achieved by the track-following servomechanism. The need for better sensing of the PES made researchers explore different techniques of servo encoding - dual frequency servo burst being one of them. This paper addresses different aspects of decoding the PES from these servo bursts. An algorithm based on the discrete Fourier transform (DFT) is used. Claims are supported by both simulation and experimental data.