[Kst] Zero calibration

Nicolas Brisset nicolas.brisset at free.fr
Tue Feb 10 21:34:43 UTC 2015

Hi Gunter,

Welcome! You're not disturbing, this mailing list is here to try and answer user questions...

Regarding the issue you describe below here are some ideas:
- you can sample one point every nth in the data wizard on the data range page (read one sample per x frames option)
- you may try the boxcar filter in the same area, I'm not sure what it does but it may help
- some of the filter plugins available could help you (high pass?)
- you may trick equations into rounding your values, something like 1.0*(value>=0.8) + 0.0*(value<0.8 && value >-0.8) - 1.0*(value<-0.8)

Then if you still can't achieve what you want you may consider writing a plugin. Try to make it as generic as possible so that it can help others too.
You can check the plugins under src/plugins, and in particular the HOWTO located there (visible online at: http://quickgit.kde.org/?p=kst-plot.git&a=blob&h=01551c1436f7c34ee008ed567fe1f2d277db0d33&hb=16d4aea302e9f9eeca86e3ad72f448b8303d31b5&f=src%2Fplugins%2FHOWTO_add_a_plugin.txt)

Hoping that helps,


----- Mail original -----
> De: "Gunter Koenigsmann" <Gunter.Koenigsmann at semikron.com>
> À: kst at kde.org
> Envoyé: Vendredi 6 Février 2015 16:37:31
> Objet: [Kst] Zero calibration
> Dear all,
> Sorry that I disturb you. But I found this exceedingly fast program
> that seems to be capable to load any length of data and am now trying
> for a long time already to do a seemingly simple thing -
> that I am hoping to archieve with it:
> I am measuring endless streams of positive and negative pulses that
> look like the following:
> 0,0,1,1,0,0,1,1,0,0,1,1,0,0,-1,-1,0,0,-1,-1,0,0,-1,-1,0,0,-1,-1,0,0,1,1,0,0,...
> The problem is that the measuring device only measures the AC part of
> the signal. The result of the measurement actually doesn't look bad.
> But
> a closer look shows that at the end of the sequence of positive
> pulses
> the zero level has dropped a little below the actual zero line and ad
> the end of the sequence of negative pulses the zero level has moved
> to a
> place slightly above the zero line.
> 0,0.00,1,1,-.05,-.05,.95,.95,-.1,-.1,-.9,-.9,-.15,-.15,-1.1,-1.1,-.1,-.1,-1.05,-1.05,0,0,-.95,-.95,.05,.05,-.9,-.9,.1,.1,1.15,1.15,...
> What I therefore need is a dynamical zero level correction. My plan
> was
> to do something like the following:
>  1.) sample one pixel in every period the signal is near zero. The
> frequency of the signal is rather stable so I just could take every
> nth
> pixel and everything would be fine.
>  2.) connect these pixels by a line. Either a linear line, a spline
>  or
> whatever kst offers me.
>  3.) Subtract the resulting curve from the one I have measured and
> declare the result to be the thing that actually happened.
> I assumed that there would be a filter that samples only every nth
> pixel or a login amp that samples only if the reference signal is
> below
> a certain value or something similar. But I didn't find anything that
> works.
> Do you have any idea?
> Alternatively is there a working link to a place that describes how
> to
> write a plug-in? I would like to avoid having to write additional
> software (and I don't have a working build system for windows but
> would
> want to use my plug-in there, if even remotely possible) but would be
> willing to, if that is really needed.
> Kind regards,
>    Gunter.
> Gunter Königsmann
> R&D
> Tel:     +49 911-6559-6025
> Fax:    +49 911-6559-776747
> www.semikron.com
> gunter.koenigsmann at semikron.com
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