Track Mis-registration Correction Method in Two-Head Two-Track BPMR Systems

Abstract

One of the main problems in a Bit-patterned media recording (BPMR) system at an ultra-high areal density is the effect of track mis-registration (TMR), which can severely degrade the system's performance. Practically, the TMR effect is controlled by the servo system. That requires some areas of record to store redundancy bits. In this paper, we propose a simple linear energy ratio finding (SLERF) technique using only the two readback signals for estimating the TMR level in two- head/two-track (2H2T) BPMR systems, which unrequired the extravagant redundancy bits. Next, we utilize the appropriate equalizers, which are accordingly designed with the estimated TMR levels, to correct the TMR effect. Moreover, we also propose a soft-information adjustment (SIA) technique that operates after obtaining the soft-information from the two-dimensional soft-output Viterbi algorithm (2D-SOVA) detectors in order to improve the bit error rate (BER) performance of recording systems. Computer simulation reveals that the SLERF and SIA techniques can impressively estimate the TMR levels and further effectively correct the TMR effect as well, respectively. Therefore, it leads to obtaining better BER performance in particular where the system is impaired by position jitter noise.