An estimation technique for nonlinear distortion in high-density magnetic recording channels

Nonlinear distortions, which limit detector performance at high recording densities, are known as the nonlinear transition shift and partial erasure. The nonlinear transition shift is known to be reduced substantially by the precompensation technique, while the partial erasure requires sophisticated nonlinear equalization techniques. In this paper, a new calculation intensive adaptive technique is presented that uses stochastic gradient method to minimize the mean squared error between actual playback signal samples and modeled signal samples. The effectiveness of the proposed adaptive approach to separately estimate these two nonlinear parameters uniquely is demonstrated by computer simulation.