Transient signal measurement and analysis of in-situ flying height test during track seeking process

In view of the fact that the head-disk clearance approaches several nanometers for the next generation magnetic recording system, head-disk contacts, especially during the seeking processes, could happen and these contacts may deteriorate the overall performance. A hardware setup using triple harmonic method for flying height measurement during track seeking as well as track following processes is described. Tradeoff is made between less ISI distortion and higher selectivity of the harmonic selection channel. The linear equalizer based on the minimum mean square error criterion (MMSE) has been developed to remove the ISI distortions. The least mean square (LMS) algorithm is used to calculate the tap weight coefficients. The results show that 1 nm accuracy for FH measurement during track seeking process can be achieved.