Denoising using Wavelet problem

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mir khadim
mir khadim 2022-2-9
评论： Walter Roberson 2022-4-10
The inbuilt MATLAB function "wdenoise" does not output the denoised signal. I used the following syntax
f8_clean = wdenoise(f8,5,'Wavelet','db4')
where "f8" is my noisy input signal, "5" is the level of decomposition, and "db4" is the chosen wavelet. The output signal "f8_clean" is supposed to be noise free to some extent, but it exactly matches with my input signal "f8".
What am i doing wrong?

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回答（1 个）

Walter Roberson
Walter Roberson 2022-2-9
Ran in:
Perhaps your noise is just very small and your signal is very regular? And perhaps you only checked to 4 digits?
format long g
t = linspace(0,1/100, 2500);
f8 = sin(t*2*pi*17) + randn(size(t))/100000;
f8_clean = wdenoise(f8,5,'Wavelet','db4');
[maxdiff, maxidx] = max(abs(f8-f8_clean))
maxdiff =
3.77285063186683e-05
maxidx =
996
[f8(maxidx), f8_clean(maxidx)]
ans = 1×2
0.412549466538199 0.412587195044517
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Adam Reed
Adam Reed 2022-4-9
I am having the same problem. I check the MSE for the denoised signal and it is on the order of 10^-26.
Walter Roberson
Walter Roberson 2022-4-10
@Adam Reed
What shows up if you plot the difference between the original signal and the denoised signal?

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