[aprssig] APRSIS32 sending conflicting position reports

Eric H. Christensen eric at aehe.us
Sat Nov 7 19:35:41 EST 2020

I think I just found a flaw in APRSIS32 (but it may not be limited to that software).

I've been seeing stations slide across my screen over the past few weeks.  I couldn't quite put my finger on it until tonight.  Here's what I'm seeing:

A non-mobile station will suddenly relocate itself a distance away only to move back to where it came from a short time later.  After working with one station, and looking at the packets being sent directly to the IS, I noticed two things: 1) the position reports are not changing, and 2) the status reports (of which I've never found to be useful) contain a properly formatted status report *with Maidenhead Grid Locator*.

So, what I think is happening is my client is seeing the position report and plotting the station as expected. It is then seeing the grid locator in the status text and moving the station to the middle of the grid, as it should per the APRS spec[0].

Having never run APRSIS32, I'm wondering if this is a setting somewhere in the software to include the grid in the status text.  I've seen so many of these stations sliding across my screen it would seem to be odd that it is an individual effort.

Eric WG3K

[0] http://www.aprs.org/doc/APRS101.PDF (pages 8, 27, and 81-82)

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