MT63
is an orthogonal frequency division multiplexed mode consisting of 64
parallel carriers each carrying a part of the transmitted signal.
There are 3 bandwidths and baudrates that fldigi implements in
MT-63:
500 Hz - 5 baud,
1000 Hz - 10 baud, and
2000 Hz - 20 baud.
The
lowest frequency transmitted is always 500 Hz. If you have a
scheduled MT63 qso or are trying to copy what you think is MT63 you
should tune the signal so that the lowest observable signal is at 500
Hz. Fldigi is capable of decoding signals that are mistuned by as much as +/- 100 Hz.
Long interleave and 8-bit extended characters are usually
agreed upon before a qso exchange begins. The default is to use
the long interleave. 8-bit extended characters allow the
transmission of Latin-1 accented characters.
MT63 is used
extensively in the Military Affiliate Radio System (MARS).