Digital PES demodulation in hard disk drive

This paper compare the performance of dual frequency servo pattern and conventional quadric servo pattern. The sampled and quantized servo bursts are divided into small windows. Each window contains exactly one period cycle of the servo burst. The sampled windows are averaged first to get an estimation of the desired servo bursts waveform. Rectifier/coherent detector are used to estimate the amplitude of the desired servo bursts waveform. PES can be calculated using the amplitude of the servo bursts. Simulation results show that the performance of rectifier and coherent detector are almost the same. If the length of the servo bursts is the same, dual frequency servo bursts can outperform conventional servo pattern.