A WSJT-X Mode That Ignores the Clock
For two decades, the major modes from the WSJT project have followed the same pattern: transmit in one period, listen in the next, decode at the end of the cycle. JTTY breaks that pattern. It was announced on September 23, 2026 with WSJT-X 3.2.0-rc1. It is a keyboard-to-keyboard mode that transmits when you press a key and prints text as it arrives, just like RTTY.
The development team describes the goal as the operating feel of RTTY with much better weak-signal performance and a much lower error rate. The target audience is clear: RTTY contesters who have watched FT8 and FT4 take over activity but still prefer running with function keys and a serial-number exchange.
The announcement is signed by K1JT, K9AN, G4KLA, N9ADG, DL3WDG, W3SZ, KJ5HST and KD0BTO. This is a release candidate, not a general-availability build. The team wants on-air testing and feedback before an early GA release of 3.2.0.
Inside JTTY: Frames, Tones and Throughput
JTTY uses a 4-tone GFSK waveform organized in 1.888-second frames, with an occupied bandwidth of about 127 Hz. Transmissions are not synchronized to UTC. They can start at any moment and usually last a few seconds. Signal subtraction and adaptive decoding help recover overlapping or fading signals, and all received and transmitted text is written to ALL.TXT.
Listen to JTTY sample file:
The most important detail for contesters is how much fits in a frame. A single frame carries only five arbitrary characters, but predefined contest formats pack much more into the same space. “CQ CQ K1ABC CQ” goes out in one frame, and a full “W9XYZ 599 107” exchange takes two. This leads to a counter-intuitive result: the more creative your macros, the slower you become. Free text runs at about 30 WPM, half the speed of the structured formats, so the stock message forms are where the performance comes from.
Function keys F1–F8 cover the usual run and S&P sequence. The macros are %M for your call, %H for the other station’s call, %E for the exchange (currently 599 plus serial) and %Q for the next queued call. You can queue messages while you are still transmitting.
JTTY vs RTTY vs FT4
| JTTY | RTTY 45.45 | FT4 | |
|---|---|---|---|
| Modulation | 4-GFSK | 2-tone FSK | 4-GFSK |
| Bandwidth | ~127 Hz | 170 Hz shift | ~80 Hz |
| Timing | Asynchronous | Asynchronous | 7.5 s T/R cycles |
| Text speed | ~60 WPM contest, ~30 WPM free text | ~60 WPM | Structured messages; 13-char free text |
| Weak-signal threshold | Not yet published | No coding gain | −17.5 dB (2500 Hz ref.) |
| Operating style | Keyboard, F-keys, live print | Keyboard, F-keys, live print | Auto-sequenced, decode per cycle |
The table shows JTTY’s position. It matches RTTY’s contest speed and live, asynchronous operation, but uses a coded waveform. The User Guide’s sample recording contains a JTTY signal weak enough that standard 45.45-baud RTTY copy would have been marginal and full of errors. The developers have not yet published a formal SNR threshold.
Downloads, Documentation and Logging Support
Installation packages for Windows, macOS and Linux are published on the official WSJT-X GitHub repository. Linux builds cover x86_64, aarch64 and, once again, 32-bit armhf, so Raspberry Pi stations can install without compiling
The new User Guide includes JTTY sections and a sample WAV file, available via Help | Download samples. The team warns that some screenshots are out of date and some text is still missing. For background, see Digital Modes – RTTY and RTTY contesting resources.
WSJT-X provides an MMTTY-compatible interface to N1MM Logger+ version 1.0.11449 or later . Typing JTTY in the N1MM callsign field launches WSJT-X in JTTY mode. The guide also includes a sample function-key file that uses JTTY’s native message formats.
Where to Find JTTY Activity
The developers suggest 14.090 MHz on 20 m as the first common meeting place. Preliminary dial frequencies have also been published for every band from 160 m to 2 m, and they are likely to change as activity grows. We track them on a dedicated page: JTTY frequencies.
A good first session starts off the air. Decode the sample WAV file to see how text accumulates on screen. If you use N1MM Logger+, make sure your FT8 setup works first, including CAT and PTT, then switch to JTTY with the rig into a dummy load and confirm that F1 sends your CQ. After that, listen on 14.090, answer a CQ, and report what you find through GitHub Issues or Discussions, or the WSJT-X user forums.
Release candidates are meant for the testing period only. Once the GA version of 3.2.0 ships, retire the rc1 build from on-air use.
Frequently Asked Questions
A: JTTY is a keyboard-to-keyboard digital mode introduced in WSJT-X 3.2.0-rc1 in September 2026. It is designed for fast RTTY-style contest exchanges and uses a 4-tone GFSK waveform about 127 Hz wide. Unlike FT8 or FT4, it has no fixed transmit/receive periods.
A: The WSJT-X development team suggests 14.090 MHz dial on 20 m as the initial meeting place for JTTY. Preliminary frequencies exist for all bands from 160 m to 2 m and may change as the mode spreads. DXZone keeps an updated list on its JTTY frequencies page.
A: You need N1MM Logger+ version 1.0.11449 or later. Configure WSJT-X with N1MM as you would for FT8, then type JTTY in the N1MM callsign field to launch WSJT-X in JTTY mode. Customize your digital function-key file to use JTTY’s contest message formats.
A: According to the developers, yes: JTTY has much better weak-signal performance and a much lower error rate than standard RTTY. A sample recording in the User Guide shows a JTTY signal that would give marginal, error-prone copy as 45.45-baud RTTY. For contest messages, its speed of about 60 WPM matches RTTY.
A: No. JTTY transmissions are not synchronized with UTC. They start when you send a message and usually last a few seconds.
A: Yes, it supports arbitrary text, but at about 30 WPM, since each frame carries only five free characters. Structured contest messages run at about twice that speed. JTTY works best for short, standardized exchanges.