How to find approximation and detail coefficient from a reconstructed signal?

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Fahim Feroje
Fahim Feroje 2015-8-29
回答： Asfaw Alem 2022-11-24
Hi I want to decompose a signal and by reconstructing this signal try to find approximation and detail coefficient from the reconstructed signal. For decomposition I used single level decomposition(Discrete Wavelet Transform-Db6) and for reconstruction I used inverse discrete wavelet transform. But using idwt I have found only approximation coefficient. But I want to find detail coefficient from original signal or reconstructed signal. How can i do this?
ss=load('Fah_2-L05.mat');
[cA1,cD1] = dwt(ss.data,'db6');
[cA2,cD2] = dwt(cA1,'db6');
[cA3,cD3] = dwt(cA2,'db6');
[cA4,cD4] = dwt(cA3,'db6');
[cA5,cD5] = dwt(cA4,'db6');
[cA6,cD6] = dwt(cA5,'db6');
[cA7,cD7] = dwt(cA6,'db6');
[cA8,cD8] = dwt(cA7,'db6');
A8 = idwt(cA8,cD8,'db6'); %approximation coefficient of level 8

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回答（2 个）

Muhammad Ramzan
Muhammad Ramzan 2016-8-4
编辑：Walter Roberson 2016-8-4
%%%may be it will help you
ss=load('Fah_2-L05.mat');
[cA1,cD1] = dwt(ss,'db8');
A1 = upcoef('a',cA1,'db8',1,l_s);
D1 = upcoef('d',cD1,'db8',1,l_s);
[C,L] = wavedec(o,8,'db8');
%%Approximattion Coff:
A2 = wrcoef('a',C,L,'db8',2);
A3 = wrcoef('a',C,L,'db8',3);
A4 = wrcoef('a',C,L,'db8',4);
A5 = wrcoef('a',C,L,'db8',5);
A6 = wrcoef('a',C,L,'db8',6);
A7 = wrcoef('a',C,L,'db8',7);
A8 = wrcoef('a',C,L,'db8',8);
%%Details Coff:
D2 = wrcoef('d',C,L,'db8',2);
D3 = wrcoef('d',C,L,'db8',3);
D4 = wrcoef('d',C,L,'db8',4);
D5 = wrcoef('d',C,L,'db8',5);
D6 = wrcoef('d',C,L,'db8',6);
D7 = wrcoef('d',C,L,'db8',7);
D8 = wrcoef('d',C,L,'db8',8);
For reconstruction you can use:
ss= A1+D1;
%%or
ss=A2+D1+D2;
%%or ss= A3+D1+D2+D3; %%and so on
Asfaw Alem
Asfaw Alem 2022-11-24
how can apply dwt and idwt in ofdm to analysis wavelet families in OFDM

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