Simulation Research Of Nonlinear Narrowband Active Noise Control System Based On Volterra Filter

The dissertation designs two kinds of new nonlinear NANC systems based on Volterra filter. One kind of nonlinear NANC system is constructed by FIR filter and Volterra filter, another by linear combiner and Volterra filter. Both systems designed here consist of two subsystems, i.e., the linear signal synthesising subsystem and the nonlinear signal synthesising subsystem. In each nonlinear NANC system, the subsystems can work independently and in parallel for reducing the fundamental frequency component and the higher harmonic components, respectively, which consequently leads to effectiveness in suppressing the nonlinearily distorted narrowband noise being targeted.In the two new nonlinear NANC systems designed in this dissertation, both the filtered-X LMS(FXLMS) algorithm and the filtered-X RLS(FXRLS)algorithm are respectively adopted to derive updating equations for control filter weights. In the case of the single tone, from numerous simulation and analyzing results, it is proved that these two kinds of new nonlinear NANC systems are of satisfactory noise suppressing performance. By extending the scenario to multi tone case, it is further proved that the designed nonlinear NANC systems based on the Volterra filter are effective in suppressing the disturbed or distorted narrowband noise, and the later system presents better performance as it is used to cancel targeted noise containg harmonics in more higher order and with more great power.Besides, in our simulations, the secondary paths in two nonlinear NANC systems considered here are all estimated by so-called off-line system identification method based on adaptive LMS algorithm.