[aprssig] Bouncing locations

Keith VE7GDH ve7gdh at rac.ca
Mon Jun 20 17:30:41 EDT 2011

Bob WB4APR wrote (on behalf of Zack KD8KSN)...

> If you go to http://aprs.fi/?call=a%2FKD8KSN-9 and view my
> path over the past three+ hours, you will see I made a trip down
> to Frazysburg and back...
> ...I know that aprs.fi plots you at your last location, but according
> I checked it this morning and it had me back home...


I didn't do enough digging to find delays of ~ 3 hours, but...

2011-06-19 16:12:49 UTC:
:`nRXqgGk/`"6^}146.760MHz T123 -060 FTM-350AR SmrtBcn_"

2011-06-19 16:14:54 UTC:
:`nRXqgGk/`"6^}146.760MHz T123 -060 FTM-350AR SmrtBcn_"
[Location changes too fast (>500 km/h)]

They are one and the same beacon. The first one was sent on RF, was
digi'd by K8GPS-4 and was gated by KB8UVN-5.

The second copy has TCPIP in the path and was gated by K9JVA.
I'm not sure if someone else grabbed it from the APRS-IS and gated
it out to RF and it was then gated back to the APRS-IS by KB8UVN-5
or if was all of KB8UVN-5's doing. There was a 2 minute 5 second

Another example...

2011-06-19 16:05:56 UTC:
:`nVuq yk/`"6y}146.760MHz T123 -060 FTM-350AR SmrtBcn_"

2011-06-19 16:08:33 UTC:
:`nVuq yk/`"6y}146.760MHz T123 -060 FTM-350AR SmrtBcn_"
[Duplicate position packet]

This one is a bit easier... no TCPIP in the path. The first one was heard
direct and gated by KB8UVN-5. The second one, with a 1 minute and
37 delay, was digi'd by N8WCT-1 and W8GUC and finally gated
by KA0AZS. There isn't any way of telling if the delay was caused
by one of the digis or the iGate or a combination of them.

The next one is a better example... no digis involved, but it wasn't
a duplicate...

2011-06-18 17:35:10 UTC:
:`nNAp zk/`"77}146.760MHz T123 -060 FTM-350AR SmrtBcn_"
[Location changes too fast (>500 km/h)]

So if it wasn't a dupe, perhaps the previous report was one
that had been delayed, making it look like the station had
travelled very quickly to the 17:35:10 UTC position. Yup...

2011-06-18 17:34:28 UTC:
:`nNXm4>k/`"7=}146.760MHz T123 -060 FTM-350AR SmrtBcn_"

and the delayed report, with a 36 second delay. Not much, but
enough to make the 17:35:10 UTC report look like it had a problem.
Conveniently, it was heard direct and gated by N8WCT-1.

2011-06-18 17:35:08 UTC:
:`nNXm4>k/`"7=}146.760MHz T123 -060 FTM-350AR SmrtBcn_"
[Duplicate position packet]

The delayed report was digi'd by N8WCT-1 and gated by AB8DD.
There isn't any way of telling which one introduced the delay. I think
you get the picture, but it appears that there could be more than one digi
or iGate introducing delays around there. It would be a lot easier for
someone right there to watch on RF and see if  one or more digis were
introducing delays. Also, someone with a vested interest could do
some digging to try and prove if all delays were caused by digis or
if iGates were the cause at least some of the time.

73 es cul - Keith VE7GDH
"I may be lost, but I know exactly where I am!"

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