[aprssig] FREQ Object Formats

[Bob Bruninga]

Over on the APRSISCE email reflector we are trying to clean up the use of
the FREQ SPEC in APRS:

We need a definitive baseline of all existing implementations of the
FREQ-OBJECT and FREQS-in-posits so that we can clean up how the APRS radios
and clients respond to these signals and how they transmit them.  The main
focus is on the radios which take more to fix than clients oftware.

We need to make up a COMPATIBILITY TABLE:  So here are the HARDWARE COLUMNS
to my knowledge that try to parse and act on FREQ info:

TM-710, TH-D72, FTM-350.  Then each of these needs separate columns for each
firmware release.

The ISSUES then are the rows.  Here is my attempt to list the issues:

Leading space:  (required, required-not, don't care) - (Y, N, X)
Xmits space:    (Transmits leading space) - (Y, N)
Requires "MHz": (Requires mixed case, allows any case)     - (Y, N)
Requires MHz_:  (Requires trailing space) - (Y, N)
Xmits MHz_:     (Transmits trailing space) - (Y, N)
Responds to offsets
Transmits offsets
Allows extra trailing zero so that +600 works, where only +60 is IAW spec
Etc

By the way, the #1 problem is people not doing the Tnnn correctly,  That is
the #1 error I see on the air. All of the tones are channelized, we do not
need to WASTE byte sending decimals!

#2) best thing we can do is NOT TRANSMIT ANY OFFSETS IF THE OFFSET IS
STANDARD.

Bob, Wb4APR