[aprssig] ARPS physical layer

[Robert Bruninga]

>> Try: http://www.tapr.org/pdf/AX25.2.2.pdf
> 
> Except that nobody's really implementing 2.2.  
> Try 2.0 instead.

Amen, 2.2 allows no flexibility in digipeater fields (Limits to
1 or 2?), which would completely fail with APRS.  After the
first hop, an APRS packet typically can look like this:

WB4APR>APRS,WIDE1-1,WIDE1*,WIDE2-1

Which would violate the 2.2 spec and die...
On the next hop, it would use up 4 digi fields.

WB4APR>APRS,WIDE1-1,WIDE1*,DIGI2,WIDE2*

And surely fail.  Since the 2.2 writers are "opposed" to
digipeating (which of course is the foundataion of APRS)...

Bob WB4APR