load S20F20.DAT
x=S20F20;
y=x(:,2);

x=[];
k=[];
N=length(y);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  4.硬消噪采用cycle_spinning技術
%  累加量
z5=zeros(N,1);
%  平移變換頻移法
for i=1:N;
    z=circshift(y.',i-1).';  %  源信號右平移
    [z1,z2]=lwt(z,'db4');    %  小波正變換
    z2=zeros(1,N/2);         %  高頻分量全部為零（主要噪聲，硬消噪）
    z3=ilwt(z1,z2,'db4');    %  小波反變換  
    z4=circshift(z3.',-(i-1)).';  %  變換后信號左平移  
    z5=z5+z4/N;
    %z5=z4;  %  平均  ?????????
end;
    
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  5.顯示
error=norm(y-z5)/norm(y);  % 相對誤差
figure(1);
subplot(3,1,1)
plot(y);
legend('original signal');
subplot(3,1,2);
plot(z5);
legend('denoised signal');
subplot(3,1,3);
%plot(1:6001,y,1:6001,z5,'r:');
compare=y-z5;
plot(compare);
legend('compare');
%plot(compare);
%legend('copmpare');