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usrp/README: described how to perform and evaluate a measurement run

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Werner Almesberger 2010-11-17 13:50:13 -03:00
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@ -14,7 +14,7 @@ characteristics.
Preparing a measurement run Preparing a measurement run
--------------------------- ---------------------------
Before measuring the characteristics of an antenne, we need to set up the Before measuring the characteristics of an antenna, we need to set up the
test environment and obtain a number of filtering parameters. The filters test environment and obtain a number of filtering parameters. The filters
are used to reduce the effect of noise on the measurements and to suppress are used to reduce the effect of noise on the measurements and to suppress
contamination from other sources. contamination from other sources.
@ -149,3 +149,45 @@ contamination from other sources.
The output are three numbers: the average (after eliminating The output are three numbers: the average (after eliminating
outliers), the minimum, and the maximum. outliers), the minimum, and the maximum.
Performing a measurement run
----------------------------
The script "fscan" performs 100 scans of the 26 channels used by IEEE
802.15.4. The frequency scan is the inner loop, so that slow changes
in environmental parameters (background noise, temperature, etc.) will
affect the spread of the results over the entire frequency range instead
of causing seemingly frequency-dependent distortions.
The script is written for a setup that uses a pair of hosts, both
sharing the same file system.
Usage: fscan out-dir [tx-power]
The output directory must not exist yet. The transmit power is in dBm and
defaults to 2.6 dBm.
Example: ./fscan testant
The full run takes approximately half an hour.
The results are filtered and averaged by the script "evscan". This script
contains the filtering parameters obtained in the preparation, described
above.
Example: ./evscan testant >testant.out
The output is a graph with frequency, average signal strength, minimum
and maximum. The format is compatible with gnuplot's "with errorbars"
(or "with errorlines") plot style.
Finally, the results can be plotted with the script "plscan", which uses
gnuplot to output either in a window or to a PNG file.
Usage: plscan [-o pngfile] file ...
More than one graph can be plotted in the same run. The file name is used
as the title for each graph. Titles are truncated at the first dot.
Example: ./plscan testant.out