MATLAB toolbox wavelet time-frequency

Question

Godefroy 2011-5-26

0
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[EDIT: 20110526 02:20 CDT - reformat - WDR]

plan time-frequency with wavelet packets D-1

I have a question about the time-frequency plan.

as the example in wavedemo -> GUI mode -> Wavelet packet D-1.

There are a graphic time-frequency plan.

I show my source code :

fe=100e3;
Te=1/fe;
N=1024;
t=[0:Te:(N-1)*Te];
f0=1000;
f1=50000;
x=chirp(t,f0,(N-1)*Te,f1);
n_tree = 4;         %Tree level number
%-------------------------------------------------------
figure;
subplot(2,1,1),plot(x);
title('signal original');
%
wpt = wpdec(x,n_tree,'db4');
plot(wpt);
bt = besttree(wpt);
plot(bt);
for i=1:(2^n_tree)
    temp = wpcoef(wpt,[n_tree i-1]);
    cfs(i,:) = temp;
end
%subplot(2,1,2),plot(cfs);
figure;
for i=1:(2^n_tree)
    subplot((2^n_tree)/2,2,i),plot(cfs(i,:));
    %title('partie signal (', n_tree ,',',i-1, ')');
end
cfs=cfs.^6;
figure;
image(cfs);

My problem is the frequency order.

I don't know how do it. i search in the toolbox...

I hope I will have a reply.

regards

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Godefroy 2011-5-27

the functions "wpdec" and "besttree" give the signal decomposition but the indic is not arranged in frequency order.

for example i want to decompose a chirp in level 2. I will have 4 frequency(as frequency 10 - 20 - 30 - 40 Hz), i should have in frequency order from 10 Hz to 40 Hz. But the function give the order as 10 -> 20 -> 40 -> 30. So i don't known how to have the good order as 10 - 20 - 30 - 40 Hz. I cannot to arrange the order manual because i need to analyze the signal with the tree and level of 4 or 5 or any more.

I hope with this details it will reply to your isssue.

regards

Yang 2011-11-25