Spline and Derivative Pt By Pt

[Alain_S]

Hi there,

I need to detect the small jumps that shows up at the end of the measured data, see the red line.

Looking at the top graph.

To do so I first fit a spline through the measured data resulting in the white line.

Finally I calculate the derivative of the spline resulting in the green line.

From that green line, one can easily find the peaks.

You may think problem solved

I would say yes in case one has the whole data at once.

I want to do the same while I receive the data point by point, the measured data I mean, the red line.

So I tried the same approach using the PtByPt vi's, but I get nowhere

See the lower graph.

Who can help me out??

Thanks !!

[altenbach · Accepted solution]

How about a simple low pass filter. Even a simple "ptbypt DC estimate" seems to work OK. Of course the data will be shifted according to the ptbypt window size, but you should be able to deal with that.

[Alain_S]

Works great!

I evalute it on multiple datasets, all variations were well detected.

Thanks a lot Altenbach!