Wavelet bandwith, centre frequency
显示 更早的评论
The Wavelet Toolbox provides the fucntion scal2frq which gives a so called pseudo-frequency to a corresponding scale.
As I understand it, each scale represents a daughter wavelet. In contrast to a periodic sine wave doesn´t a wavelet represent a frequency range rather than one frequency?
How can one calculate the bandwidth of a wavelet?
Is there a way of getting the actual function of the scaled wavelets used in cwt in order to perform an fft on them?
采纳的回答
Wayne King
2011-11-19
Hi Chris, there are a couple things you can do:
1.) If you want to see the support of wavelets at different scales, you can input a shifted Kronecker delta sequence
x = zeros(1000,1);
x(500) = 1;
cfs = cwt(x,1:2:64,'sym8');
% next part obviously not needed
for nn = 1:32
plot(cfs(nn,:)); pause(0.2);
end
2.) The other thing is that the Wavelet Toolbox now has a DFT-based continuous wavelet transform, implemented in cwtft.m and an inverse CWT in icwtft.m. The wavelets supported in cwtft have their Fourier transforms explicit. See the reference page for cwtft.m
Also see:
for some examples.
更多回答（1 个）
Wayne King
2011-11-19
Hi Chris, here is a quick example of the first option above:
x = zeros(1000,1);
x(500) = 1;
cfs = cwt(x,1:2:64,'sym8');
Fs = 1000;
wavdft = abs(fft(cfs(5:10:30,:)'));
wavdft = wavdft(1:length(x)/2+1,:);
freq = 0:(Fs/length(x)):500;
plot(freq,abs(wavdft),'linewidth',2);
xlabel('Hz'); ylabel('Magnitude');
legend('Scale 10','Scale 30','Scale 60');
类别
在 帮助中心 和 File Exchange 中查找有关 Continuous Wavelet Transforms 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
