Tham khảo tài liệu 'adaptive filtering applications part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 202 Adaptive Filtering Applications contaminated SEP was set to -10 -15 and -20 dB. The last row of Figure 3 sn shows the simulated primary channel SEP signal at -15dB with EEG and WGN. Adaptive noise canceller for SEP extraction using mean square estimation The SEP extraction method under the adaptive noise canceller ANC framework derived from the Mean-Square-Error was firstly introduced and evaluated by some of the present authors in Lam et al. 2005 . From the adaptive filter theory Haykin 2001 and the configuration of the ANC shown in Figure 1 the SEP extraction problem can be solved as a linear ANC problem since the FIR adaptive filter is used named as ANC-SEP approach in this study . The commonly used error measure is the Mean-Square-Error MSE defined as jMSE E e2 ri where E . represents the ensemble operator . The minimisation of the MSE results in the Wiener normal equation under some statistically independent and signal wide-sense stationary IVSS assumptions. The optimal solution of Wiener normal equation can be denoted as w n Rt P 3 where p is the cross-correlation vector between s n and r n and R . is the autocorrelation matrix ofrfn which can be written as p E s n r n R E r l r A 4 As discussed in many literatures the well-known least mean squares EMS algorithm is a stochastic gradient based adaptive algorithm to obtain the optimal solution of Jmse- The updating of the adaptive filter coefficient vector can be denoted as Haykin 2001 w n w n-l 2 uimse n r n 4 where films is the stepsize which is one of the most important factors that controls the initial convergence rate and steady state error of the LMS-ANC for SEP extraction. Generally a big stepsize yields rapid convergence but larger steady-state misadjustment error. A small stepsize yields slow convergence but a corresponding smaller steady-state misadjustment error. There exists a theoretical lower and upper bound of the choice of films details can be referred to Haykin 2001 . Usually the choice
