[aprssig] Weather Alert APRS Message

Dan Srebnick k2dls at k2dls.net
Fri Jul 28 17:43:27 EDT 2017


I'm putting together a process to query the xml from my local NWS
office, see if there are any active alerts, and gate them in weather
alert format to RF.  After putting together information from various
sources, I've come up with the following parsed APRS format:

K2DLS-13>APRS::NWS-WATCH:291800z,Flash_Flood_Watch,NJ_Z020, {SJ8AA

Is this format correct?

Now for some more specific questions about data formats.

Q1: Are the underscores required in what Xastir refer to as the
"alert_tag" field?  I seem to get different display results with or
without them in the Xastir Wx Alerts window, but none of them are what
I expect.

Q2: Is there a standard for county format?  One approach is described
by http://www.aprs.org/APRS-docs/WX.TXT (NJ_MONMOU) and another is
described in the Xastir comments (the derivative of the UGC value as
displayed in my packet, NJ_Z020 rather than NJZ020).

Q3: Is the compressed time value after the { required to be 5
characters or can I leave off the last 2?  or see Q4...

Q4: If I just use AA or 00 for the last two characters mentioned in Q4
is that a problem or should I use a random algorithm?  Or is this value
to support multiline messages?

Any insight would be appreciated.


Dan Srebnick

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