A new digital mode has arrived in WSJT-X 3.2: JTTY. Designed for fast RTTY-style contest exchanges and keyboard-to-keyboard communication, JTTY combines the familiar operating style of traditional RTTY with modern weak-signal performance and improved error handling. WSJT-X is developed by the WSJT team and software, documentation and downloads are available from the official WSJT-X website.
Unlike FT8 and FT4, JTTY does not use fixed transmit and receive time slots. A transmission can start at any time, giving operation a much more natural RTTY-like feel. The mode uses 4-GFSK with an occupied bandwidth of around 125 Hz and provides approximately 30 words per minute for arbitrary text and up to 60 WPM for optimized contest exchanges.
Built for digital contesting
Contesting is the obvious first application. Callsigns, reports and serial numbers can be exchanged efficiently using programmable function keys, while structured contest messages make efficient use of each transmitted frame. Support is already available in current versions of N1MM Logger+, making JTTY particularly interesting for operators familiar with traditional RTTY contesting.
The combination of narrow bandwidth, weak-signal performance and asynchronous operation could be especially useful on crowded bands or when propagation becomes difficult.
More than a contest mode
JTTY could also become an interesting tool for emergency communications and preparedness. Unlike highly structured modes intended mainly for exchanging callsigns, signal reports and locators, JTTY can send arbitrary text. That means operators can exchange short situation reports, locations, equipment requirements, weather observations and other operational information directly over an HF radio link.
Its lack of synchronized transmit periods may also be an advantage for temporary or field stations. Precise computer clock synchronization is not required simply to exchange messages, while the narrow signal and forward-error-corrected digital format are designed to maintain reliable copy under conditions where conventional RTTY may become increasingly error-prone.
For preparedness communications this is an attractive combination: narrow bandwidth, weak-signal capability, error correction and real keyboard-to-keyboard messaging using ordinary amateur-radio equipment and a computer. As with any computer-based digital mode, a resilient field setup still needs reliable power for the radio and computer, suitable interfaces and an antenna system capable of getting the signal through.
Still very new
JTTY has made its public debut in the WSJT-X 3.2 release cycle, so operating practices, software integration and preferred frequencies will continue to evolve as more radio amateurs experiment with it on the air. Visit the official WSJT-X website for the latest software releases, documentation and project information.
JTTY may have been developed primarily with RTTY-style contesting in mind, but its ability to move readable text efficiently over difficult radio paths could make it equally interesting when the objective is not another QSO in the log, but simply getting the message through.
Get on JTTY and other digital modes
FlexRadio – digital modes integrated at the software level
FlexRadio transceivers are particularly well suited to digital modes. SmartSDR provides virtual digital audio through DAX together with CAT control, allowing applications such as JTTY, RTTY, FT8 and other computer-based modes to communicate directly with the radio in software without a separate external sound-card interface. This applies across the current FLEX-8000 and Aurora families.