[aprssig] APRStt 4 digit grid squares...justification

[Bill Vodall]

>> Then making a DTMF contact is as easy as pressing ONE BUTTON.

Is there a 'preamble?'   Is there a check sum of some sort to validate
the transmission?

I've listened to repeater sysops and, back in the old days -
autopatch users -having all sorts of trouble with Touch Tone systems.
That was with good signals on a clear channel.

Perhaps a SOTA activation with this technology would be a good test drive.

Bill, WA7NWP

PS.  for facilities with Internet - why not just use voice?  It's a
simple process now to send audio off to Google to be decoded.