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From: nethaji anandhavalli on 9 Apr 2010 05:43
hi,
i need to denoise the signal based on threshold value,eg: ecg.
which filter design would perform well?
if any, pls guide me with functions.
From: Wayne King on 9 Apr 2010 06:13
"nethaji anandhavalli" <mydreamprojects(a)yahoo.com> wrote in message <hpmsr8$9ia$1(a)fred.mathworks.com>...
> hi,
> i need to denoise the signal based on threshold value,eg: ecg.
> which filter design would perform well?
> if any, pls guide me with functions.

Hi Nethaji, I think you need to be more specific. For example, wavelet denoising is very different than filtering in the "Fourier" sense. Then there are alternative methods such as a Savitzky-Golay smoothing that basically does a polynomial regression. Which method works the best depends on a lot of factors. For example, can you characterize the noise as localized in frequency?

Wayne
From: nethaji anandhavalli on 9 Apr 2010 06:32
As u said, i am first applying of dwt on my signal. upon applying the dwt, wavelet coefficients would be produced. now i intented to apply the filtering scheme to segregate the noisy and original signal at wavelet coefficients. here i need the better filter design, which need to be based on threshold value, it should separate my original and noisy signal at this coefficient level.
From: Wayne King on 9 Apr 2010 06:53
"nethaji anandhavalli" <mydreamprojects(a)yahoo.com> wrote in message <hpmvnk$jsg$1(a)fred.mathworks.com>...
> As u said, i am first applying of dwt on my signal. upon applying the dwt, wavelet coefficients would be produced. now i intented to apply the filtering scheme to segregate the noisy and original signal at wavelet coefficients. here i need the better filter design, which need to be based on threshold value, it should separate my original and noisy signal at this coefficient level.

Look the help for wden()

>>doc wden

There are a number of threshold selection rules supported.

There are also denoising utilities for wavelet packets:
wpbmpen, wpdencmp

I think wden() is a good place to start. See if that helps you.

Wayne
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