A method for evaluating error rate after ECC considering position jitter

摘要

Since there is degradation of SNR along with increasing areal density of hard disk drive, it is getting difficult to maintain adequate raw error rate and a role of ECC is getting more important. A current trend of read channels tends to have RLL codes with long code length for the sake of high code rate, but on the other hand error propagation is becoming controversial problem. Meanwhile, accomplishment of high areal density needs read/write design considering not only linear density but also track density. We developed a method for evaluating error rate after ECC considering position fluctuation of a head in cross track direction. The results obtained from this method show good agreement with real data.