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[aprssig] Color code for fading stations?

Robert Bruninga bruninga at usna.edu
Mon Feb 12 16:55:43 UTC 2007

> On Behalf Of (SV2AGW)George Rossopoulos
> Subject: [aprssig] Color code for fading stations?
> What is the color code for stations that are about to removed?
> I mean when a station beacon arrives it is displayed normal, 
> after 5 minutes the station color needs to change and so on 
> as there is no new beacon.

I would suggest CYAN.  See rationale below:

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

The original color attributes for all symbols are:

WHITE:....Full-up APRS station that is message capable 
GRAY:.....Tracker/other station without message capability 
CYAN:.....Moving with CSE/SPEED or a Dead Reckoned Station 
BLUE(drk).The previous position of a MOVED station or object 
YELLOW:.. Your active OBJECTS you are transmitting to the net 
VIOLET:...Objects received from others 
GRAY(drk) Old Symbols not updated in the last 80 minutes or more

BLACK:....Old Symbols that have been "killed" by the originator 
RED:......Emergency, Alarmed, or otherwise unknown symbols 
CIRCLE: ..Circles show size of position ambiguity .1,1,10,60 mi

The default for "old-no-longer updated" symbols to be clearly of
no current interest was set to 80 minutes.  (It was originally 2
hours, but then in the 90's with the APRS satellites, this was
changed to 80 minutes which is shorter than any possible orbit,
so that stations from last orbit had faded-to-gray before a new
orbit.  This seemed reasonable to apply to the age of all old
objects)...  I call this category "fade-to-gray" to indicate
these objects are no longer to be considered as part of the net.
This 80 minuted definition also allows for 2 chances for a
30-minute beacon from a fixed station to be heard.

The difference in the original APRS between a FRESH posit
(WHITE) and a STALE posit (CYAN) was 1 minute, but if you are
not going to be doing minute-by-minute dead-reckoning, then
maybe 5 minutes is OK.   In the original APRS, these CYAN
symbols were dead-reckoned each minute to show the propable
position with time.  The different color, and the bright line
drawn back to the reported posit-dot clearly showed the last
known position, and also showed the growing uncertainty of the
dead reckoned posit now being shown in CYAN.


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