WSJT-X (FT1)

WSJT-X (FT1) is the application that puts the FT1 weak-signal mode on the air. It’s a fork of the venerable WSJT-X that integrates FT1 directly into the program thousands of operators already use for FT8, FT4, and friends — so there’s no brand-new software to learn. FT1 simply appears alongside the modes you already run, inside the familiar WSJT-X waterfall, decode window, and logging workflow.

What’s in the fork

• The FT1 modem — coherent 4-CPM with turbo equalization — wired into WSJT-X’s C++ audio and UI pipeline.
• Mode selection alongside the existing modes, so you switch into FT1 as easily as any other, with FT1’s waterfall bandwidth and RX/TX goal posts drawn in.
• The same 77-bit, WSJT-X-compatible message formats, so your logging and workflow don’t change.

The FT1 ecosystem

This is one of two apps built on the same FT1 core: WSJT-X (FT1) for operators who live in WSJT-X, and the chat-first Tempo app for off-grid messaging. Curious how the mode works under the hood — coherent CPM, turbo equalization, and the cellular-style IR-HARQ retransmission scheme? Read the FT1 protocol deep-dive →.

Being a fork of GPL’d WSJT-X, the project is open source under GPLv3, and it’s where FT1’s on-air implementation is actively developed — including current work to wire up live IR-HARQ. Build it from source to get on the band.