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[aprssig] SSID for RF only Station with backup power

Robert Bruninga bruninga at usna.edu
Tue Apr 10 18:05:53 UTC 2007


I'm sorry, but I have to respond to some more sentences I have
seen on this thread.  These are taken out of context and are not
necesaarily the exact intended meaning of the writers...   But
out of context, they do trigger concerns at how APRS is often
preceived compared to its potential... Nothing personal at all,
but here are my comments on a few of these...

> When mobile, I don't care about anyone but other mobile 
> stations generally.

APRS is not just a vehicle tracking system.  But it is great to
see that this station has a 2-way APRS system in his car so that
he can see the situational-awareness around him that APRS
provides...

> The reality is that a large number of icons is not useful.  
> Does the  station move?  That's important... sometimes.  
> Is it infrastructure or is there a human near it?...
> - that's important but is impossible to determine from 
> the current use of icons.  

Actually, the original APRS symbols going back to 1993 do have a
lot of important attributes.  The problem is that these 11 or so
attributes are not displayed on many APRS clones.  Even the
human activity bit is defined, but not implemented or displayed
in many programs.  Someone looking at a map can select "active
stations only" and only those stations with an operator present
will be displayed for a quick assessment of communications
capabilities.  See the attributes that are supposed to be
displayed on an APRS symbol on the map:

http://www.ew.usna.edu/~bruninga/aprs/symbols.html

> The other problem is that we could have 60,000 icons and 
> ... thus most programs will end up supporting incompatible 
> subsets of available icons.

That is why we introduced the OVERLAY system back in 1996.  This
requires NO symbol updates or any software changes.  The Overlay
character allows any one of a number of basic SYMBOL types to
display overlay characters.  Using these symbols and overlays,
over 540 different "symbols" can be displayed for all of these
basic symbol types without ANY updates to any software:  CARS,
BOATS, TRUCKS, CIRCLES, SQUARES, TRIANGLES, STARS, NWS,
AIRCRAFT, WX, ARRL, CIVIL DEFENSE, BOXES, VANS, SHELTERS.

The problem is some APRS clones that never fully implemented
overlays in the first place.  If they supported OVERLAYS on all
symbols as was originally intended, then we could be adding an
additional 500 or so new symbols -and- be using now, up to 2100
unique symbol combinations again, without any "symbol updates or
obsolescence".

So I strongly encourage all software to properly display
overlays to give APRS the flexibility that was intended.  Then
we can focus on the best basic symbol types to add as needed.

WB4APR, Bob







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