JTTY: The Brand New Digital Amateur Radio Mode!
In my early days of amateur radio, back in 1985, there were a few operators with computers trying out RTTY Mode while I had absolutely no access to a computer! JTTY is a brand-new, period-free digital mode being developed by K1JT, ported into JTDX-VU by VU2CPL. It is designed for fast, RTTY-style keyboard-to-keyboard communication. Because it uses 4-GFSK (4-level Gaussian Frequency Shift Keying) with an occupied bandwidth of about 125 Hz, it offers much better weak-signal performance than traditional RTTY (Radio Teletype used Audio Frequency Shift Keying or AFSK). Crucially, JTTY is not locked into rigid 15-second cycles like FT8—transmissions can start and stop at any time.
1. Accessing JTTY
- Mode Selection: JTDX-VU features one-click band and mode buttons right on the main interface. Simply click the JTTY mode button to switch over.
- Dedicated Screen: Once selected, JTDX-VU transitions to a dedicated JTTY layout that is specifically optimized for keyboard operations rather than standard sequencing.
2. Receiving
- Free-Flowing Decodes:Click the Monitor button to start receiving. Because JTTY is period-free, decoded messages will appear dynamically as they come across the waterfall, rather than dropping in all at once every 15 seconds.
- Click-to-Pick: To answer a station you see in the decode list, just click their callsign. JTDX-VU will automatically queue that station for your next transmission.
3. Transmitting and QSOs
- Auto CQ:JTDX-VU includes a unified Auto CQ button located directly beneath the Monitor button.Clicking this will start a hands-off CQ run for JTTY, complete with a built-in time limit so it doesn’t run endlessly if you step away.
- Keyboard-to-Keyboard: For conversational QSOs, you can type free text dynamically into the JTTY screen and send it in real-time.
- Macros: If you are contesting or making rapid DX contacts, the JTTY screen provides 24 customizable macro buttons to quickly fire off standard exchanges without typing.
4. Logging
In your ADIF log file, the QSO is saved under the mode MFSK with the submode JTTY.
When you finish a QSO, JTDX-VU handles the logging formatting automatically.
Contacts are logged with standard RTTY-style 599 / 599 signal reports.
5. Frequencies
The WSJT-X development team has established a preliminary list of dial frequencies for JTTY, which serve as the initial meeting spots for the mode.The primary hub of activity is on the 20-meter band at 14.090 MHz, which intentionally overlaps with traditional RTTY watering holes.
Here are the recommended HF dial frequencies:
| Band | Recommended Dial Frequency | Notes |
| 160m | 1.838 MHz | Preliminary frequency |
| 80m | 3.575 MHz | Located in the narrowband digimodes segment |
| 40m | 7.090 MHz | Preliminary; verify against local IARU band plans and current activity |
| 30m | 10.140 MHz | Located in the narrowband digimodes segment |
| 20m | 14.090 MHz | The primary initial meeting place for JTTY |
| 17m | 18.100 MHz | Preliminary frequency |
| 15m | 21.090 MHz | Preliminary frequency |
| 12m | 24.920 MHz | Preliminary frequency |
| 10m | 28.090 MHz | Preliminary frequency |
Because JTTY is not locked into fixed UTC cycles, you do not need to wait for a specific second to start transmitting. You can simply watch the waterfall around these frequencies, find a clear 125 Hz slice, and begin your transmission. It is worth noting that because JTTY is still relatively new, these recommendations are experimental and may shift slightly as operational experience grows.