Question about wavelet and reconstruction
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Dear all, I am studying wavelet and focusing on the signal reconstruction. I noticed that the function 'upcoef' just work for the reconstruction: http://cn.mathworks.com/help/wavelet/ref/upcoef.html
At the end of this page, I also noticed that upcoef is equivalent to an N time repeated use of the inverse wavelet transform.
Then I tried to test it with the following code:
t=0:2*pi/999:2*pi;
b0=sin(t);
figure,plot(b0);
[cA,cD]=dwt(b0,'db4',3);
D = upcoef('d',cD,'db4',3,length(b0));
figure,plot(D);
[cA,cD]=dwt(b0,'db4');
[cA,cD]=dwt(cA,'db4');
[cA,cD]=dwt(cA,'db4');
D=idwt([],cD,'db4');
D=idwt([],D,'db4');
D=idwt([],D,'db4',length(b0));
figure,plot(D)
However, results by two methods are different. Could anyone tell me what's wrong in the code?
Thanks, Tang Laoya
답변 (1개)
Wayne King
2016년 10월 4일
One problem you are having is that DWT does not take the 3 input you are using. DWT only does a single-level wavelet transform unlike wavedec. The 3 input to DWT above is NOT being used. It has no effect on the output.
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