[aprssig] APRStt Callsign and Checksum
matt.kc8bew at gmail.com
Tue May 12 19:10:30 CDT 2009
I didn't understand what the "units digit" but I did some more research and
I now understand it.
(I didn't remember that from math class) The units being the ones place.
Got it now.
Thanks for the help.
Matt Murphy, kc8bew
Muskingum Co. ARES EC
On Tue, May 12, 2009 at 14:00, Robert Bruninga <bruninga at usna.edu> wrote:
> > Thanks for the info. I wasn't it reading
> > right the first time. I have a further question though.
> > The total for my callsign is 101 like yours
> > so my checksum is 1. Where do we get 1 from 101?
> >> ... You just add up all the keys in the callsign,
> >> and keep only the units digit of the sum.
> We will make it clearer in the docs when we get the chance.
> > On Tue, May 12, 2009 at 10:14, Robert Bruninga
> > <bruninga at usna.edu> wrote:
> > It would be nice if someone would write an APRStt
> > GENERATOR routine for everyone to use. They could just
> type in
> > their callsign, and out comes the DTMF keys to put into
> > This automatically generates the 2-key conversion and
> > An ON_LINE generator would even be better!
> > > I have a question about the APRStt checksum.
> > > What is it and what is it for?
> > Since the callsign is only entered once into a DTMF
> memory for
> > easy transmission, we thought it should have a checksum
> > greatly minimize the chance for errors. You just add up
> all the
> > keys in the callsign, and keep only the units digit of
> the sum.
> > That then is the checksum digit. If APRStt reecives a
> > string and the checksum does not match, then there is an
> > The APRStt DTMF string for callsigns is:
> > AcccccccccccVK#
> > Where V is a user selected overlay byte (or two byte
> > Where K is the checksum (treat ABCD keys as HEX)
> > Where each letter of the callsign is encoded using the
> > text system
> > See www.aprs.org/aprstt/aprstt-user.txt
> > Bob, WB4aPR
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