[aprssig] aprssig Digest, Vol 105, Issue 13
kf4lvz at yahoo.com
Mon Mar 18 15:22:38 CDT 2013
> Message: 3
> Date: Sun, 17 Mar 2013 14:15:24 -0400
> From: Robert Bruninga <bruninga at usna.edu>
> To: aprssig at tapr.org
> Subject: [aprssig] APRStt works!
> Message-ID: <a4dfdc828440c3c490b13ea5bc2172a1 at mail.gmail.com>
> Content-Type: text/plain; charset="windows-1252"
> We used APRStt successfully yesterday to allow anyone with any HT to report
> their positions along our Marathon by entering only the DTMF code ?B1MM*??
> followed by their callsign from DTMF memory. The MM number was converted
> by a lookup table to the exact position of the mile mark. Further, anyone
> could report themselves anywere in the 10 mile grid to the nearest 600? or
> so using the DTMF format ?B2XXYY*?
> We think that has great potential to expand the use of APRS at events,
> since everyone in the club could input data, not just the 10% that had APRS
> See the web page:
> More to come when Byonics eventually decides to make these DTMF adapters
> available. Right now, only 3 of us have alpha models for experimentation.
> But be thiking of how you can use EVERYONE in your club at your next event
> to enter data. For example, how we report Boy Scout troop scores at our
> camporees: http://aprs.org/aprsevent.html
> Our local Repeater owner also said he would be happy to put an APRStt
> decoder on the repeater input so that non-APRS mobiles in the area could
> easily be seen on APRS too?
Bob, I see a bug in your callsign encoding. You use a single number key to encode a number but you use a number and then a letter to encode the letters. The problem comes when you perhaps lose one of the letter keys (interference, bad key, etc.) which is then interpreted as a straight number. Perhaps you should amend your format such that numbers are prefixed with 0. This keeps the 2-symbol-per-character encoding consistent and also provides a flag for signalling a numeric.
I know that uses up a little bit of airtime but it isn't much when talking about the callsign and adds a bit of error checking.
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