[Xastir] Weird plotting

[Tom Russo]

On Thu, Mar 01, 2007 at 07:24:37PM -0500, we recorded a bogon-computron collision of the <ddclark_lists at kj5kg.net> flavor, containing:
> Good afternoon folks,
> 
> Has anybody noticed anything weird with plotting tracks?  I have 1.8.5
> (latest CVS) running on both my home and work Fedora Core 5 boxes.  I
> notice that the tail sometimes has two coursed plotted from the same posit
> but going in different directions and other weirdness.  Rather than trying
> do describe it, check out
> 
> http://www.kj5kg.net/snapshot.png
> http://www.kj5kg.net/snapshot2.net
> 
> I'm pretty sure that I'm not driving like my trail would suggest!  It's
> also interesting to note that Mike's K9MTN trail shows the same behavior
> in the same place!
> 
> The data in snapshot.png is from my TNC at home and snapshot2.png is via
> APRS-IS at work.
> 
> Also, the same phenomena happen when I download my track from findu.

This looks suspiciously like a digi that's holding packets too long before
digipeating them.  Stuff like this has shown up in discussions on APRSSIG
from time to time.  My memory's kinda dim on the subject, but as I recall
it is stale packets being re-transmitted long after later posits are created.

If you're seeing the behavior in a specific location, it's likely that the
nearby digi is malfunctioning somehow.  You might try searching the APRSSIG
archives for details, as I don't remember exactly what the mechanism is or
what the comment traits were.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick