[aprssig] New Year! Clean up the APRS garbage...

John Langner WB2OSZ wb2osz at comcast.net
Thu Jan 8 19:07:55 CST 2015


Here is something quick and easy you can do to get a glimpse into what is
happening on your local APRS network.

Run "direwolf" and enable logging to capture activity for a while.  This
will produce a CSV (comma separated values) type file which can be imported
into a spreadsheet or easily parsed for further processing.

The interesting fields, in this case, are:

(4) Source station.  This is mentioned only to distinguish it from the heard
station.

(5) Station heard.  This can be the same as the source, when heard directly,
or a digipeater.  This isn't always accurate because some digipeaters don't
insert their calls correctly.  But that's a another topic for another day.

(6) Audio level of station heard.  This an un-calibrated value because it
depends on the receive volume setting.  What we are concerned about is the
ratio between different stations.  

If you are using Linux (or Cygwin) something like this can be used to
extract the audio level and station heard.  Sort them to make the lowest and
highest values more obvious.

cat *.log  | gawk -F , '{ print $6 " " $5 }' | sort -n

TM-D710A and FTM-400DR transmitters heard directly have essentially the same
values so we could probably assume this is around the ideal deviation level
to aim for.   In a recent small sample, I see only one station with a lower
number.  Most are higher with a couple nearly twice as high.   



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