[RTTY] 2Tone Update on new technique

[David G3YYD]

During the WAE RTTY contest John GW0SKA and I made about 1100 Qs each.
Independently both of us thought that about 4% of the Qs were improved due
to the new technique. The new technique being to make use of repeated
character strings, which in a contest means callsigns and the exchange, to
enhance the decode by combining them together to produce a fresh and in most
cases a more accurate decode.
 
I find in a typical contest, I have to ask for repeats on about 8 to 10% of
the total Qs. So this reduces the number of Qs made by asking for a repeat
by about half - a significant reduction. Other contest/stations may have
different "mileage". 
 
Further not all stations send their callsigns/exchange in a  suitable format
for this technique to work.
 
I have since made some enhancements to further reduce false positives. I
also fixed a problem in that I had used the wrong internal flag for squelch
so it was turned off if the squelch was turned on. Now it will work if
squelch is turned on but the squelch is open. Proves the value of testing
with more people than one.
 
I have also added an additional menu option that inhibits the output when
the two input strings have already decoded correctly. Doing this will reduce
Di window clutter, but still leave the op with the option to have it display
for all string matches.
 
I will do some more testing before I issue a new version of 2Tone.
 
73 David G3YYD