Comparison of discrete-time approximations for continuous-time nonlinear systems

This work addresses the problem of approximating the sampled input-output (i/o) behavior of continuous-time nonlinear systems using discrete-time Volterra models. For an exactly band-limited nonlinear system for which a Volterra representation exists, the discrete-time Volterra model exactly corresponds to the sampled continuous-time Volterra kernels. Physical systems, as they are causal, are never exactly band-limited. Thus, a modeling error is introduced. By relaxing the causality condition and allowing a small processing delay, it is shown through simulation that more accurate discrete-time Volterra models, compared to sampled continuous-time Volterra models, can be generated.