How can I apply lifting scheme to my own wavelet?
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Shaik Ahmad
el 8 de Mayo de 2016
Comentada: Shaik Ahmad
el 16 de Mayo de 2016
I have implemented and added a bi-orthogonal wavelet function to the wavelet toolbox using wavemngr function. Now I want to apply lifting scheme to that wavelet. When I apply liftwave(wname) function it is showing "Error using liftwave (line 45)Invalid wavelet name".
In the wavenames also I am not getting my wavelet name. Please provide a solution to add my wavelet in the lifting wave.
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Wayne King
el 13 de Mayo de 2016
Hi Shaik,
filt2ls is your friend. You use filt2ls with the filters (include both the analysis and synthesis filters) and that will return the lifting scheme. Then, you use that lifting scheme with lwt.
For example:
[LoD,HiD,LoR,HiR] = wfilters('bior3.1');
ls = filt2ls(LoD,HiD,LoR,HiR);
load wecg;
[CA,CD] = lwt(wecg,ls);
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Wayne King
el 15 de Mayo de 2016
Editada: Wayne King
el 15 de Mayo de 2016
Where did you get this biorthogonal filter pair? It does not satisfy the criteria for a biorthogonal (wavelet) filter pair. For one example, the product of the Fourier transforms of the lowpass filters at 0 frequency (DC) should be equal to 2.
In your case, it is equal to -2. The sum of elements in your rlp filter is -2.
A couple things you need to ensure are the following, let G_0() and G_1() denote the Fourier transforms of your lowpass filters and H_0() and H_1() denote your highpass filters
G_0(\omega)G_1^*(\omega)+H_0(\omega)H_1^*(\omega) = 2
G_0(\omega)G_1^*(\omega+\pi)+H_0(\omega)H_1^*(\omega+\pi) = 0
where the * denotes the complex conjugate.
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