wavelet decomposition of a signal
1 次查看(过去 30 天)
显示 更早的评论
hi, i want to decompose a signal with wavelet in 5 subbands:
delta (0–4 Hz), theta (4–8 Hz), alpha (8–15 Hz), beta (15–30 Hz), and gamma (30–60 Hz) ,use db4"_
i found wavelet toolbox menu but cant use it,can you help me?
thanks.
0 个评论
回答(2 个)
Jan
2013-8-18
Use wavedec() to calculate the wavelet decomposition and wenergy to extract the energie in the decomposition.
e.g.:
[C, L] = wavedec(signal, waveorder, wavekind);
[~, energies] = wenergy(C, L);
Note, that the wavelet deomposition in a specific decomposition level does not exactly represent an actual frequency band. This can be only done, using trigonometric functions for decomposition - however, in hat case you end up with the discrete Fourier transform.
However, you can calculate corresponding frequencies (i.e. pseudo frequencies) for a specific wavelet family and level of decomposition (look at centfrq() on that matter). If you carefully choose the wavelet family and wavelet order, you get a wavelet decomposition, that roughly corresponds to the desired bands.
For your use case, one would choose Daubechies order 3 Wavelets and six levels of decomposition. Then the decomposition levels 1 to 5 in reverse order should just about match the required bands:
L1: gamma, L2: beta, L3: alpha, L4: theta and L5: delta.
1 个评论
Afiqah Abu Samah
2017-3-15
Hi, I want to ask how to calculate the energy of 2-D wavelet decomposition. I know that function wenergy2 can be use, but I want to know how it can be calculated since I want to use single level 'dwt2' function and decompose the images level-by-level instead of using this; [C,S] = wavedec2(X,2,'bior3.7'). (I have my own reason why I need to decompose it like that)
If 'dwt2' is used, I can't calculate the energy using 'wenergy2' since I didn't know how to get the 'C' array.
Please help me, give me some ideas how to solve this.
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Discrete Multiresolution Analysis 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!