Thursday, May 23, 2013

The case of the disappearing weather objects.

I have just spent what seems like several hours trying to find out why my weather station data sent by Cumulus to the APRS network vanishes without trace. I have tried using the wxnow.txt method of generating APRS weather objects in APRSISCE and that does work, but unfortunately it messes with the MYCALL setting in my Kenwood TM-D710 converse mode TNC. So I thought that I would avoid the problem by getting Cumulus to send the data to APRS-IS directly.

The data packets were being sent but they never showed up on aprs.fi. I produced debug logs for both Cumulus and APRSISCE. These showed the packets being sent. So where did they disappear to?

To cut a long story short, Cumulus was sending the data packet with a path of TCPXX*. This is listed as "deprecated" in the APRS spec but it is actually blocked by the APRS-IS network software. The CWOP (Citizens Weather Observer Program) which I believe runs on an older version of the software, is not so picky so no-one had encountered the problem before. Can you believe that I must be the first person to try sending weather data to the APRS network using the Cumulus software?
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