JTTY
A newer weak-signal typing mode from the makers of FT8, sent in short continuous frames rather than timed turns.
What does it sound like?
A steady four-tone warble, similar to FT4 but without the regular on-off rhythm of timed turns.
Who uses it?
Amateur radio operators trying WSJT-X 3.2, where it first appeared (as a release candidate in September 2026).
Where and when can I hear it?
The HF ham bands; new and still uncommon.
The science
JTTY sends typed text in frames of 1.888 seconds and can start transmitting at any time rather than waiting for a fixed turn, using four-tone GFSK modulation (frequency-shift keying with smoothed transitions) about 127 Hz wide. The decoder uses signal subtraction and adaptive decoding, which help it recover text from overlapping or fading signals.
Why use it?
It is meant to feel like traditional radioteletype (RTTY), where you can start sending whenever you like, while offering far better weak-signal performance and a very low error rate. Contest operators get function-key exchanges and can queue messages while transmitting, and it can link to the popular contest logger N1MM Logger+ through an MMTTY-compatible interface.
Lore
JTTY was introduced in WSJT-X 3.2.0-rc1, a release candidate dated September 23, 2026, from Joe Taylor (K1JT) and the WSJT Development Team, the group behind FT8.