MT63


MT63 is a digital :Category:Radio modulation modes|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 amateur radio bands.

Features and Attributes

MT63 distributes the encoding of each character over a long time period, and over several tones. This code and symbol spreading implementation is key to its robustness under less than ideal conditions. The MT63 mode is very tolerant of mistuning, as most software will handle 120 Hz tuning offsets under normal conditions.
ModeSymbol RateTyping SpeedDuty CycleModulationBandwidthITU Designation
MT63-5005 baud5.0 cps 80%64 x 2-PSK500 Hz500HJ2DEN
MT63-100010 baud10.0 cps 80%64 x 2-PSK1000 Hz1K00J2DEN
MT63-200020 baud20.0 cps 80%64 x 2-PSK2000 Hz2K00J2DEN

MT63 Latency

One shortcoming of MT63 is that robustness is somewhat compromised with the short interleaver.
Latency is more than 6 seconds with the long interleaver.
The typical character transmission delay is 12.8 seconds with Long Interleave Mode.
ModeECC ModeLatency
MT63 500 Hzshort12.8
MT63 1Kshort6.4
MT63 1Klong12.8
MT63 2Kshort3.2
MT63 2Klong6.4
PSK31-<1

Media

MT63 is seeing a resurgence in its popularity on shortwave with the VOA Radiogram but the software used to encode the text is not using the Varicode that MT63 used in its original design.
Modern software that codes MT63, such as Fldigi, has opted for base128 that is essentially ASCII-7. However, the only interleaving options have become long and short, as the medium interleaving mode has become redundant.
MT63 has been mooted as a modulation format for Time Signal Stations, but the implied system does not use Varicode.

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