[http://www.qsl.net/wm2u/mt63.html] Developed by Pawel Jalocha, SP9VRC. It is intended as a conversational mode between two or more Hams. It has 64 tones spaced 15.625Hz apart, in the 1kHz bandwidth. It uses FEC error correction which, even if 25% of the character sent is obliterated, it will give perfect copy. Each character is spread over many tones to reduce interference from other radio stations, and spread over several seconds to avoid noise bursts such as lightening. Despite this seemingly slow data throughput, good text speed is maintained at 100 wpm. It is therefore a very robust mode.
Download available here: http://www.navymars.org/central/reg4/al/MT63.htm