[aprssig] More on DTMF Messaging

[Robert Bruninga]

>> monitoring the APRStt simplex channel (147.51)....
> 
> Whoa!   Where did this frequency selection come from? 
> It's not a 20k spaced channel.
> Both 147.50 and 147.52 are in use in my state 

Yes, it is unfortunate that a few states went to 20 KHz spacing
when all the radios these days more or less can work pretty well
at the original 15 KHz spacing used in most of the other states.
But putting that aside...

The reason we are looking for a FFF.FF frequency is because
there will be lots of these local objects and to make sense out
of all of them on the APRS-IS, we will need to use all three of
the FFF.FFxyz (xyz) bytes to differentiate them.

> Also be aware, there is a proposal here in TX to use these
pairs for 
> D-Star 2m repeaters:
> 
> 146.450/147.450 MHz
> 146.460/147.460 MHz
> 146.470/147.470 MHz
> 146.480/147.480 MHz
> 146.490/147.490 MHz
> 
> Further details here:
> 
>
www.txvhffm.com/index.php?option=com_content&task=view&id=88&Ite
mid=38