Nonlinear filter for inversion of channel distortion

The ill-posed nature of direct deconvolution has prevented its use in applications such as channel equalization or inversion of transducer distortion. In this paper we discuss the use of a recursive nonlinear filter. The design of the proposed filter is accomplished in two stages. First, a constrained least-squares technique is employed to obtain, off-line, a filtered signal from a typical distorted signal. Then this pair of signals is used in a model identification scheme, to arrive at the nonlinear recursive filter. Since the final filter is recursive, and synthesized in one of the two alternative structures, both the memory and computation requirements are low enough to permit efficient on-line implementation.