Key points...
1) Transmissions last for 4.48 seconds as compared to 12.64 s for FT8.
2) Works at about the same speed as RTTY for contesting.
3) For a rough comparison with RTTY, it was noted that in simulated mid-latitude moderate conditions RTTY has been shown to yield character error rates less than 10% only when SNR exceeds –1 to +4 dB, depending on the software modem in use. FT4 offers a sensitivity advantage of about 10 dB over RTTY.
4) As many as 50 stations can operate in a 3 or 4 kHz passband with little interference, even when signal strengths differ by as much as 60 dB.
5) July 15th 2019: General Availability (GA) release of WSJT-X 2.1.0 and FT4.
From the document..."FT4 is a special-purpose mode designed for rapid-fire contest QSOs. It serves this purpose very effectively, but like FT8 the mode is not useful for more extensive conversations. FT4 uses much less bandwidth than RTTY and provides reliable decoding at much lower signal levels. Stations using low power and compromise antennas can participate effectively in a contest using FT4."
Thoughts...
It will be interesting to see how this develops and what impact it will have. Will it help kill off RTTY? Will it be used outside of contests?
The software can be downloaded here... http://physics.princeton.edu/pulsar/k1jt/wsjtx.html
Update... See this video presentation about FT4 from Joe Taylor K1JT. The piece about FT4 starts around 14 mins...
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