MT63 is a digital radio modulation mode for transmission in high-noise situations developed by Pawel Jalocha SP9VRC. MT63 is designed for keyboard-to-keyboard conversation modes, on HF HAM bands. MT63 distributes the encoding of each character over a long time period, and over several tones. This implementation is key to its robustness under less than ideal conditions.The data encoding is performed utilizing 64 different modulated tones. By doing this, it is able to include a large amount of extra data in the transmission of each character. This allows the receiving equipment to accurately identify and verify the transmitted character even when 25% of the character data is obliterated. MT63 implements an elaborate set of error correction techniques. It uses a Walsh function that spreads the data bits of each character across all 64 of the tones of the signal spectrum and simultaneously repeats the information over a period of 64 symbols within any one tone. This takes between 3.2 and 12.8 seconds, depending on the error correction mode chosen. The combination results in superb impulse noise rejection. At the same time, in the frequency domain, significant portions of the signal can be masked by unwanted noise or other transmissions without any noticeable effect on successful reception.
{play}http://www.pa4rm.com/attachments/070_mt63_500.mp3{/play} MT63 500 test sample
{play}http://www.pa4rm.com/attachments/070_mt63_1000.mp3{/play} MT63 1000 test sample
{play}http://www.pa4rm.com/attachments/070_mt63_2000.mp3{/play} MT63 2000 test sample