How make this curve bit smooth or how to reduce some spikes?

Hi,

I want to make this curve bit smoth by minimizing some spikes or I want remove some high frequency content from the curve.

How I can do it? I to do it by applying some moving average filter or band pass filter, etc.?

Answer 1

[Star Strider]

‘I to do it by applying some moving average filter or band pass filter, etc.?’

That depends entirely on the nature of the noise. None of those will work with broadband noise because they are all essentially frequency-selective filters. For broadband noise, use the Savitzky-Golay filter (Signal Processing Toolbox sgolayfilt function), or the 'sgfilt' option in the smoothdata function. Wavelet denoising is also an option.

The best way to determine if the noise is band-limited is to first takt the fft of it. That plot will tell you.

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[Nisar Ahmed]

@Star Strider It is not a seismic signal, infact a well log curve, I do not think noise matters here.

How can I apply moving average here, it may help to reduce some data points and spikes will minimize automatically.

[Star Strider]

I would experiment with the smoothdata function (linked to in my original Answer). It has other options in addition to 'sgfilt'. One of those whould do what you want.

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[Nisar Ahmed]

@Star Strider Thank you, these are good options

[Star Strider]

As always, my pleasure!

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Answer 2

[Chunru]

Try the median filter, where X is your data, N could be around 10 (try it out).

Y = medfilt1(X,N) 

[Nisar Ahmed]

Thanks @Chunru it works, but how can I apply moving average here, it may help to reduce some data points and spikes will minimize automatically...

[LALIT PANKAJ GROVER]

You can use:

a = movmean(A,K)

A is vector or matrix on which you want apply mean average.

K is a silding window along which you receive your mean.