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Data Smoothing


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Hi everyone !

Once again congrats for this forum. For someone like me (coming from a totally different background) it is a great opportunity to learn more about LabVIEW. :thumbup:

I sorted my shift register issue out.

On the pic below you can see two waveform probes. I would need an appropriate filter to get rid of the "noise" in the right one to get it to similar shape as the left one. I am using "7.1 full" version and put in the filter express. However rectangular smoothing seems to be insufficient and curve fit is too hectic on the original data. :thumbdown:


I red about point to point filter and array filter maybe an array filter would be better :wacko:

Could someone help out



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QUOTE (Antoine Châlons @ Oct 21 2008, 08:49 AM)

I agree with Anders, I almost always use median filter instead of average (and not only for signal acquisition).

I agree. Moving averages can be tricky when doing signal processing. It "can" smooth a trace efficiently in some circumstances but it has the bad habit of shifting your signal temporally. Frequency filtering is much better for time-critical traces.

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The "best" filter to use often involves a solid understanding of both your signal and noise source(s), it's fairly large topic in analytical science. Median filters are a very powerful swiss army knife type of filter, and produce excellent results in many situations. A properly set low-pass filter can often do wonders to data where noise is of much higher frequency than your signal, as can a properly constructed convolution filter. I believe all of these options are available to "Full" versions of LabVIEW, though I can't say for sure in your case, I skipped the 7.X generation.

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Thanks for the input !

Below the result with a medianfilter (right) compared to the curve hoe it should look like ... :lightbulb:


the curve doesn't look too bad, but I can't apply low pass somehow, as the data was already filtered through low pass 5Hz, 2 oder Butterworth (tried with express vi "filter")

I just need a god da... curve fit or whatever too smooth it ... :headbang:

P.S. Am from Cape Town / South Africa = someone from the same city :unsure:



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