NONLINEAR EQUALIZING APPARATUS

A nonlinear equalizing apparatus used for a digital magnetic recording medium is provided. The nonlinear equalizing apparatus according to the present invention includes a linear filter for linear filtering the input value r.sub.k, a pattern dependent filter including 2.sup..tau.+v tap values selected by the respective patterns (b.sub.k-n+v:k-n+1,b.sub.k-n-1:k-n-.tau.) of future v and past .tau. bit data transition absolute values and N taps p.sub.n (b.sub.k-n+v:k-n+1,b.sub.k-n-1:k-n-.tau.) for outputting the value obtained by multiplying the selected tap value with the current transition (x.sub.k-n), and (wherein, x.sub.k-n =(a.sub.k-n -a.sub.k-n-1)/2.di-elect cons.{-1, 0, }, b.sub.k-n =.vertline.x.sub.k-n.vertline..di-elect cons.{0, 1}, b.sub.k-n-1:k-n-.tau. =(b.sub.k-n-1 b.sub.k-n-2 . . . b.sub.k-n-.tau.), b.sub.k-n+v:k-n+1 =(b.sub.k-n+v b.sub.k-n+v-1 . . . b.sub.k-n+1), n=0, 1, 2, . . . , N, and N is a predetermined integer not less than 1+v) a detector for obtaining an error value e.sub.k by a subsequent equation, with respect to all combinations of current and future data sequences ##EQU1## (wherein, .function..sub.m is the linear filter) and detecting current data assumed in the combination by which the minimum error square value is generated as the original data a.sub.k. According to the present invention, it is possible to effectively display the nonlinear distortion of the digital magnetic storing channel generated by the interaction between adjacent data and to remarkably reduce a modeling error compared with a conventional model in which the influence of the future bit cannot be considered, by displaying the nonlinear channel of a high density digital magnetic storing apparatus as transition pulses selected according to the pattern of the transition absolute value of the future v bits and the past .tau. bits.