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torgert
Denmark
1 Posts |
 Posted - 07/20/2004 : 06:18:52 AM
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I frequently plot the bit error rate (BER) of a communication system versus the signal input power (PWR), and would like to plot the following:
X axis: PWR
Y axis: log10(log10(BER))
My current method is first to first calculate log10(BER) and then plot that on a logarithmic scale. That works fine, but it is extra work, and the Y axis ticks has to be in log10(BER) instead of simply BER.
So: Any tips, tricks or ideas on how to directly get a double logarithmic plot? |
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verrallr@a
Canada
44 Posts |
Posted - 07/22/2004 : 11:55:05 AM
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Because there is no Log(Log) plot within Origin, you probably cannot do you task much easier than you indicate. But, you can plot the graph PWR vs BER as you wanted.
You just need to make a double log plot of the data that you want. Then plot the Double Log plot vs PWR on Scatter plot, as indicated below. The main problem will be how to make the Y-axes.
Below, I have some a table with some representative data. It consists of a PWR X axis, and some data for BER and also we calculate Log(Log(BER)). Then make a Scatter Plot of the Log(Log(BER)) data vs PWR. I wanted to plot the Scatter Plot, but I don't see how to do that, as an image. You can put a Right Y Axes to Show this LogLog(BER) data (or not, as you choose). To create a nonlinear function for the Left Y Axis, I'm don't quite know how. Possibly, you can use the method described only for Origin 7.5, "Using Functions to Create a Nonlinear Scale on a Second Axis" in Help. You would put 'layer.y2.label.formula$ = "10^(10^y)" '. The problem is that that doesn't give integral tic marks for this Axis, and only seems to created a Right Y axis. Another way that gives integral tic marks is if you want only one (or a couple) of scales for Y. Then you can create tic marks based on your own, for the Left Axis, and then create that as a Template. (Finally, I thought you could create tic marks, based on wherever you want them, but, at the moment, I don't see how.)
X(PWR) Y-BER Y-Log(Log(BER))
1 10 0
2 100 0.30103
3 1000 0.47712
4 10000 0.60206
5 100000 0.69897
6 1000000 0.77815
7 1E7 0.8451
8 1E8 0.90309
9 1E9 0.95424
10 1E10 1
I wanted to Plot Graph here, but don't see how to do that.
Anyway the plot is simple, but getting the axis the way you want is less simple. Possibly, others could show how to do this.
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Double logarithmic