Why is output in lcr so coarse graind ?

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cssdata
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Joined: Fri Dec 04, 2015 9:12 pm
Location: Esslingen, Germany

Why is output in lcr so coarse graind ?

Post by cssdata » Fri Dec 11, 2015 9:56 pm

Why is the output in lcr so coarse?

During a frequency scan of a 22uF capacitor, we found the impendance values Z looking good but the other output (including Cp Cs, etc.) rounded very roughly.
In the e.g. the capacity of the DUT varies from 17.3xxuF to 15.9xxuF but *all* values were rounded to 0.00002F. This is true with the command line tool and web-app. All in all, not very helpful.
I looked in "lcr.c" and found out that the output formats all the values with "%.5f". I changed all the format strings to from "%.5f" to"%e" and now I get the correct output readings from 1.73e-5 down to 1.59e-5 as expected. Is there a reason for this "%.5f" format I'm not aware of? E.g. are there any other programs expecting the output to be in this very format? BTW. the web-app also shows the correct curve now. However, the web-app labeling on the Y-axis is still wrong. The values there read "1.7000000m" instead of, say "17uF". But this is the way it was before I patched "lcr.c" - so I did not introduce this bug.
I also found one minor bug in index.html of the lcr web-app. In line 2625 the value for "Gp" was missing in the select box. This caused all diagrams left of "Gp" (Cs,Cp,Ls,LpRp,Q,D) to show the wrong diagram. "Cs" showed "Gp", "Cp" showed "Cs", and so on. Inserting a "<option value="6">Gp [S]</option>" and shifting the values below by "1" fixed the problem.

I'm very new to the pitaya and I'm using the latest eco-system as of last week (0.94something).

73,
Christoph

PS: If I ever write an app for the pitaya it will cost 50 bugs but will be free for everyone who does not have FaceBook

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redpitaya
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Re: Why is output in lcr so coarse graind ?

Post by redpitaya » Mon Dec 14, 2015 12:19 pm

Hi,

Thank you for info.
We are currently working on fixing some bugs in Impedance analyzer app. and this report will help us.

All Best, Red Pitaya

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