[aprssig] Beacon parsing help

Jim (List) jim.list at stuckinthemud.org
Tue Mar 26 03:20:25 EDT 2019

Thanks Bob (and others who have responded).


Monitoring 1.7m beacons last night I found 1500 that were duff, so happy to just reject the 0.1% that don’t conform.


What is noticeable is there seems a common theme amongst the bad packets, in that they are being generated by a few buggy bits of software (specifically a radiosonde system and a MMDVM repeater), or are manually entered.






From: Robert Bruninga <bruninga at usna.edu> 
Sent: 23 March 2019 13:38
To: Jim (List) <jim.list at stuckinthemud.org>
Cc: TAPR APRS Mailing List <aprssig at lists.tapr.org>
Subject: Re: [aprssig] Beacon parsing help


I think your thinking is correct.  These are bad packets.  No new position report formats have been added in morethan a decade.

There are plenty and they work fine.



On Fri, Mar 22, 2019 at 5:14 PM Jim (List) <jim.list at stuckinthemud.org <mailto:jim.list at stuckinthemud.org> > wrote:

Looking for help from someone experienced in parsing ARPS beacons to assist
in understanding differences in the position beacons I'm seeing from various

I'm dusting off some code I wrote a few years ago to parse APRS beacons,
which at the time was decoding everything perfectly and was used on various

However, monitoring positional data today it's picking up beacons with
differences that do not appear in the specification.

Are these differences recent changes to the APRS spec, or are they clients
that are just sending bad data?

Monitored beacons are listed below, with a note of what I'm seeing wrong.

K3NAL-1>BEACON,qAR,KK4ZWW-1:!146.64-000000z3812.05n/07623.07WrT146 R25 NetTu
1930 Mtg 4th Th
*** Appears to have a frequency, a dash and a time inserted before the Lat,
plus the Lat letter is in lower case 

W9GO-3>BEACON,qAR,KC9MWQ-1:!146.91-4028.82N/08609.33W# Kokomo Repeater Club
*** Another with what looks like a frequency and a dash before the Lat

#QTH T=18.5C, U=13.2V, WX3in1Plus2.0
*** Has "222024S" inserted before Lat

71304/ 13.0V
*** Too many digits after the decimal in both Lat and Long

W3EPE-3>APTT4,WIDE1-1,WIDE2-1,qAO,BEARCK:!4048.31N07531.34W#PHG51304/ W1 
*** No symbol table ID

POINT6>APN382,qAR,N6MLD-1:!4702.46NS11359.W#PHG5860/ 11,22,21,33 harc's pt6
thanks mso wx.
*** No digits after the Long decimal

*** Lat N/S and Long E/W duplicated

N/01117.042E`Radiosonde Tracker - Based on kxyTrack 1.0-1805
*** Too many digits after the decimal in both Lat and Long

DO2ATR-10>APGW1K,TCPIP*,qAC,T2KA:!5005.05N/007 0.07E#DO2ATR iGate APRS
432.500 JO30MU
*** Spaces in the Long that don't conform to position ambiguity

Jim, G1HUL

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