Significant digits / Precision on chart

[rgutie]

My data consists of pretty large numbers with resolution in the thousandths place (30,000,000,000.124 Hz for example). Labview shoes this number on the y-axis as 30.5E9 regardless of whether the actual value is 30,000,000,000.111 or 30,000,000,055.555. Can you adjust the precision or sig figs for the axis?

If not what is the best way to show this on a chart without actually changing the data? Right now I am just normalizing the data to the first entry, so every measurement is compared to a reference value. I end up with a value of 55.444 using the example above. 

[RavensFan · Accepted solution]

You can change the display format of the axis to Floating Point rather than Automatic or Scientific Notation.  Right click Properties, Display Format, and change the drop down to Y-axis

Unfortunately, LabVIEW doesn't have a way to set the commas to group the digits.

[BertMcMahan]

One other thing you can do: if you use Advanced Formatting in the dialog RavensFan mentioned, you can add arbitrary test to sort of "make up" your own formatting.

For example, instead of displaying 30,000,000,055.555, you could display 30G+55.555 Hz (G for Giga, or T for Trillion, etc) to get the visible number a little smaller.

[altenbach]

I would probably display is as delta-HZ, .(the difference to the reference, i.e. relative to 30GHz). Also much easier to read.

Be aware that DBL is only good for about 15 decimal digits and you are getting close to that, so if calculations are involved, you might run into accuracy and conditioning issues.

What is the experiment?

[rgutie]

I am using a spectrum analyzer for a frequency counter at 30 GHz. I'm measuring the stability of a 10 MHz crystal oscillator that is used for a reference for an upconverter. 

I like the idea of having the "30 GHz + X Hz" but my frequency of interest is sometimes 30 GHz, sometimes 20 GHz, sometimes 8 GHz, etc. So that would only work for one case it sounds like.

[RavensFan]

You can programmatically change the display format of the axis.  So for 8GHz, set the format to "8 GHz+  %.3f Hz"   and for 20 "20 GHz+  %.3f Hz" depending on the values and the offset you put into the data.

[Yamaeda]

Going with the Delta-idea, i'd put the base value in the scale title, so it's something like 'Frequency delta (20 GHz)' instead of changing the scale text.

[rgutie]

Can you change the title of the chart from the diagram? If so how? Graph property node doesn't seem to have that. 

[Yamaeda]

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@rgutie wrote:

Can you change the title of the chart from the diagram? If so how? Graph property node doesn't seem to have that. 

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It's X-scale --> Name label --> Text

[rgutie]

Maybe that's not available in NXG?