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[aprssig] One more question on POS ambiguity....

Robert Bruninga bruninga at usna.edu
Sun May 4 15:06:09 UTC 2008


> I run APRSDOS (+10 years on same laptop) and 
> I usually keep it on a map of 10 miles...
> I'm plagued by certain WX stations...etc...
> that show up all around me, but are really located 
> +30 miles away. When I click on them it says "vicinity". 

The biggest problem is the "positionless" weather format used by
WinAPRS and by some digipeaters that have added stand-alone
Weather Stations that send out the position for the weather
station only once an hour or so (with no WX data), but send out
weather (with no position information) every 10 minutes.

I was adamantly opposed to this method in APRS since it was
introduced in 1995, because it means:
1) Weather station position reports with NO weather!
2) Weather reports with no clue where the weather is!
3) Latency as much as an HOUR for the two to be combined to have
any meaningful value!

Make that TWO HOURS in a net where the first weatherless
position report got collided...

APRS was designed around COMPLETE information in each packet.
No dependency on prior knowledge or assemiliation of data.  If
you get a WX packet (complete format) then you got everything
you needed right then complete.

These positinoless-weather and weatherless-position packets are
also very furstrating for the TRAVELER.  You can pass completely
through a state, and have numerous weather stations on your
Mobile Display LIST, but have no clue where they are.  Because
in an hour you have completely passed through the area, you have
gotten many Weather updates, but have never received a position!
And with some of the stupid paths people use, the weather could
be coming in from two states away.

I sincerely wish that such positionless weather stations use
only a SIMPLEX path so that  we don't get this 83% useless
information spread over areas far beyond their value.

So... With these weather stations you have a 83% chance of
getting a POSITIONLESS weather report before you get an actual
Weatherless position report from those stations.  APRSdos will
take that first senseless POSITIONLESS Weather report and do its
best job of putting it on the global map somewhere.  So it puts
it in the neighborhood of the first digipeater that heard it.
(you must live close to a digi)...

Later, an hour or more, when it finally does get a position
report (without any weather) from that weather station, then it
can correctly put that station on the map.

APRSdos normally does not auto-refresh the map, so you can see
what it accumulates while you were away from the screen.  This
is nice for seeing if someone passes through the area.  But then
I guess you can accumulate as many as 6 of these "vicinity
plots" on these positioinless weather reports, until you finally
get a posit...

Two fixes.
1) Just hit space bar when you return (re-draws the map)
2) Set AUTO-REDRAW.  I think it is under the MAPS menu..?

But then you miss the fun of seeing what happened all day while
you were gone...

I suppose I could disable vicinity plots for WX stations.  But
it is nice to at least see the weather in the vicinity ... Until
you finally learn where that positionless weather is coming
from...

"stump off"...

Bob, WB4APR

After running for a few hours, my 
> screen is covered with these vicinity circles, unitl I hit 
> the space bar. Why do these stations appear as vicinity, but 
> on Findu they show up where they belong?
>  
>  
> For example:
>  
> N8VIM, a WX APRS station thats 40 miles SW of me almost 
> ALWAYS shows up as a "vicinity WX Station". Is it because he 
> uses a different path for the POS packet vs WX data packet? 
> It looks like he's got WIDE2-2 for WX packets, WIDE2-2 for a 
> BEACON packet i.e. (  2008-05-04 01:00:13 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >BEACON,WIDE2-1,qAR,N1UEC-1 
> <http://aprs.fi/?c=raw&limit=&call=N1UEC-1> :Pepperell, MA. 
> WX station  ) What good does this packet do? and I can't tell 
> what he's using for the POS packet.
>  
>  
>  
> From APRS.FI I got the following raw data w/time stamps to 
> assist w/troubleshooting....
>  
>  2008-05-03 23:02:27 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,TRACE,qAo,NE1B <http://aprs.fi/?c=raw&limit=&call=NE1B> 
> :!4240.85N/07133.99W_PHG2230/Pepperell WX station, LT4
>  2008-05-03 23:04:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,NE1B 
> <http://aprs.fi/?c=raw&limit=&call=NE1B> 
> :$ULTW0051003F01B5242D27DCFFF78883000103E8007B0478000F0000
>  2008-05-03 23:09:13 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> >APRS,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :!4240.85N/07133.99W_PHG2230/Pepperell WX station, LT1
>  2008-05-03 23:09:14 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,NE1B 
> <http://aprs.fi/?c=raw&limit=&call=NE1B> 
> :$ULTW004B003501B6242D27DDFFF78883000103E8007B047D000F0022
>  2008-05-03 23:14:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0055000001B4242D27DEFFF88883000103E8007B0482000F0000
>  2008-05-03 23:19:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B4242D27DFFFF88883000103E8007B0487000F0000
>  2008-05-03 23:24:14 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B4242D27E0FFFD8883000103E8007B048C000F0000
>  2008-05-03 23:29:13 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,NE1B 
> <http://aprs.fi/?c=raw&limit=&call=NE1B> 
> :$ULTW0000000001B4242D27DFFFFD8883000103E8007B0491000F0000
>  2008-05-03 23:34:13 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B4242D27DEFFFC8883000103E8007B0496000F0000
>  2008-05-03 23:39:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> >APRS,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :!4240.85N/07133.99W_PHG2230/Pepperell WX station, LT1
>  2008-05-03 23:39:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B4242D27DEFFFC8883000103E8007B049B000F0000
>  2008-05-03 23:44:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B4242D27DEFFFD8883000103E8007B04A0000F0000
>  2008-05-03 23:49:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,NE1B 
> <http://aprs.fi/?c=raw&limit=&call=NE1B> 
> :$ULTW0000000001B4242D27DEFFFD8883000103E8007B04A5000F0000
>  2008-05-03 23:54:12 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B3242D27DEFFFB8883000103E8007B04AA000F0000
>  2008-05-03 23:59:14 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >APRS,WIDE2-2,qAo,KB1MTS 
> <http://aprs.fi/?c=raw&limit=&call=KB1MTS> 
> :$ULTW0000000001B2242D27DDFFFB8883000103E8007B04AF000F0000
>  2008-05-04 00:01:16 UTC: N8VIM 
> <http://aprs.fi/?c=raw&limit=&call=N8VIM> 
> >BEACON,WIDE2-2,K1LVA-1 
> <http://aprs.fi/?c=raw&limit=&call=K1LVA-1> ,qAO,K1LVA-1 
> <http://aprs.fi/?c=raw&limit=&call=K1LVA-1> :Pepperell, MA. WX
station





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