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git-svn-id: http://moon:8086/svn/matlab/trunk@153 801c6759-fa7c-4059-a304-17956f83a07c
2021-03-22 20:28:22 +00:00
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+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%                                                    %
+%          Normalized LMS Algorithm                  %
+%                                                    %
+% Written By: Sundar Sankaran and A. A. (Louis) Beex %
+%             DSP Research Laboratory                %
+%             Dept. of Electrical and Comp. Engg     %
+%             Virginia Tech                          %
+%             Blacksburg VA 24061-0111               %
+%                                                    %
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+randn('seed', 0) ;
+rand('seed', 0) ;
+
+NoOfData = 8000 ;	% Set no of data points used for training
+Order = 32 ;		% Set the adaptive filter order
+
+Mu = 1.0 ;		% Set the step-size constant
+
+x = randn(NoOfData, 1) ;% Input assumed to be white
+h = rand(Order, 1) ;	% System picked randomly
+d = filter(h, 1, x) ;	% Generate output (desired signal)
+
+% Initialize NLMS
+
+w = zeros(Order,1) ;
+
+% NLMS Adaptation
+
+for n = Order : NoOfData
+	D = x(n:-1:n-Order+1) ;
+	d_hat(n) = w'*D ;
+	e(n) = d(n) - d_hat(n) ;
+	w = w + Mu*e(n)*D/(D'*D) ;
+	w_err(n) = norm(h - w) ;
+end ;
+
+% Plot results
+
+figure ;
+plot(20*log10(abs(e))) ;
+title('Learning Curve') ;
+xlabel('Iteration Number') ;
+ylabel('Output Estimation Error in dB') ;
+
+figure ;
+semilogy(w_err) ;
+title('Weight Estimation Error') ;
+xlabel('Iteration Number') ;
+ylabel('Weight Error in dB') ;