[aprssig] Mic-E Position Ambituity in APRS

Robert Bruninga bruninga at usna.edu
Tue Jan 8 12:53:41 EST 2008

> I have a D700.  What does *it* do to 
> the GPS Lat/Lon data when Pos-ambig is
> turned on? 

In the normal APRS format.  Unavailable digits of precision are
replaced with a SPACE.

In the D700 (Mic-E format), unavailable digits of precision in
the latitude are replaced with the letter "Z" (not zeros).  The
Longitude then is assumed to have the same level of precision.

When a person enters his estimated position into a D7 or D700
manually, he only enters those digits he knows.  Then he uses
the position ambiguity menu to INDICATE how many extra digits of
precision he is not using.  The result is exactly the same.  

On decoding of the Mic-E format, the position used by the client
program should not insert "0's" into those unused positions, but
SPACES just like the full APRS format does.  Again, this is not
truncation, but reproducing at the receipent exactly what the
sender intended.


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