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Re: Can I create "limit lines" ? Can I check if data is within them.

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Am 26.09.2013 09:19, schrieb drkirkby@gmail.com:
>
> So I'd like a line which is -37 dB from 0 to 1000 MHz

You could draw such lines e.g. as arrows:

set arrow from first 0, first -37 rto first 1000, 0

> Up to the range 0 to 1000 MHz, anything which is above -37 dB is a
> failure, but between 1000 and 2000 MHz, something is permitted to be
> as high as -33 dB from 1000 to 2000 MHz, and -30 dB from 2000 to 3000
> MHz. Is there any way to show such lines on the graph? I know I could
> alter my data file, and add extra colums which show this, but I'm not
> keen to do that, as the data files are in a standard format, and I
> don't want to alter that.

Do this either with arrows, or use inline data:

plot '-' with steps
0    -37
1000 -33
2000 -30
3000 -30
e

The development version allows to define inline datablocks. Here, you 
would do

$db <<EOD
0    -37
1000 -33
2000 -30
3000 -30
EOD
plot $db with steps

> Those measurements were made on a Agilent / HP 8720D vector network
> analyzer (VNA). The VNA allows one to set limits, and indicates at
> any points the measured data fails to meet the specification. For
> those devices, they easily meet the spec. Is there any way in Gnuplot
> to do such testing, so Gnuplot could be configured to print PASS or
> FAIL on a plot, depending on the contents of the data?

You can use the 'stats' command to extract some statistical data 
(version >= 4.6.0):

datafile='mydata.dat'

stats [0:1000] datafile using 1:2
if (STATS_max_y > -37) {
     set label at first 500, graph 0.1 center 'PASS' lc rgb 'green'
} else {
     set label at first 500, graph 0.1 center 'FAIL' lc rgb 'red'
}
stats [1000:2000] datafile using 1:2
...

If you have more ranges, this could also be iterated.

Christoph

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Thread

Can I create "limit lines" ? Can I check if data is within them. drkirkby@gmail.com - 2013-09-26 00:19 -0700
  Re: Can I create "limit lines" ? Can I check if data is within them. Christoph Bersch <usenet@bersch.net> - 2013-09-26 09:54 +0200
    Re: Can I create "limit lines" ? Can I check if data is within them. Christoph Bersch <usenet@bersch.net> - 2013-09-26 09:55 +0200
      Re: Can I create "limit lines" ? Can I check if data is within them. "Dr. David Kirkby" <drkirkby@gmail.com> - 2013-09-26 05:30 -0700

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