Optimum design of channel filter for digital magnetic recording

To increase recording density while maintaining satisfactory data reliability, optimum channel filters are designed by taking into account the effects of intersymbol interference and noise simultaneously. The concept of eye pattern, used in communication theory, is utilized for evaluating the effect of intersymbol interference. The eye patterns are calculated assuming linear superposition of individual reproduced pulses. Filter parameters are optimized by employing an iterative approximation method so as to maximize the signal-to-noise ratio of the worst-case data. The results show that channel equalizations are effective for an amplitude detection system but not effective for a peak detection system. The recording density limits for several recording systems are also obtained.