A fork of fldigi that adds native TCI (Transceiver Control Interface) support: CAT rig control and full-duplex RX/TX audio over a single WebSocket connection to an ExpertSDR / SunSDR / AetherSDR-class SDR server — with no hardware CAT port and no virtual audio cable. Everything else is stock fldigi 4.2.13 (all the usual digital modes, logging, etc.).
| Platform | How |
|---|---|
| Windows 11 (x64) | Download fldigi-4.2.13-tci-win64.zip from Releases, unzip anywhere, run fldigi.exe. No installer. |
| Linux (x86‑64 / PC) | Download fldigi-4.2.13-tci-x86_64.AppImage from Releases, chmod +x it, and run — nothing to install. Or build from source. |
| Linux (ARM64 / Raspberry Pi) | Download fldigi-4.2.13-tci-aarch64.AppImage from Releases, chmod +x it, and run. For 64‑bit Raspberry Pi OS (trixie) on a Pi 4 / Pi 5. |
| macOS (Intel & Apple Silicon) | Build from source — see BUILDING.md. |
The Windows zip and both Linux AppImages (x86‑64 and ARM64) are built by GitHub
Actions from the tagged release and each carries a BUILD-INFO.txt naming the
exact commit; the ARM64 build is verified on the Raspberry Pi 5. (If an AppImage
won't start with a FUSE error, run it with APPIMAGE_EXTRACT_AND_RUN=1, or
sudo apt install libfuse2t64 on trixie.) There is no prebuilt macOS binary:
an unsigned Mac app can't be distributed without an Apple Developer certificate,
so macOS is source-build (a bundle you build opens normally).
Full, copy-paste dependency and build steps are in BUILDING.md (Debian/Ubuntu/Raspberry Pi OS, and macOS Intel/Apple Silicon). The shape of it:
git clone https://github.com/K5PTB/fldigi.git
cd fldigi
autoreconf -vfi # needs gettext/autopoint — macOS also needs it on PATH; see BUILDING.md
./configure # macOS needs an FLTK_CONFIG line — see BUILDING.md
make -C src -j4 # builds just the app (skips the man-page docs)
./src/fldigi…but install the dependencies first — see BUILDING.md.
TCI (Transceiver Control Interface) is a WebSocket protocol used by ExpertSDR3, SunSDR, and AetherSDR-class SDR servers. This fork speaks it directly, so fldigi can control the radio (frequency, mode, PTT, S-meter) and exchange receive/transmit audio over one network connection — replacing both the serial/hamlib CAT link and the soundcard / virtual-audio path a hardware setup would otherwise need.
Select it in Rig Control → TCI and Soundcard → Devices → TCI, then set
the ws:// address and port (default 50001). On a multi-slice radio, choose
which receiver fldigi drives (for rig control and audio alike) under
Rig Control → TCI → Rig.
TCI support here is new and under active testing. The intent is to contribute it upstream to fldigi once it has been sufficiently tested. If you find any issues associated with TCI, please open an issue on this repo — reports from real-world use across different radios and platforms are exactly what get this feature ready for upstream. Your help would be appreciated.
Based on fldigi 4.2.13. The only addition is the TCI feature; non-TCI behavior is unchanged. For the full list of modes, features, and documentation, see the upstream project:
- Upstream source: https://sourceforge.net/projects/fldigi/
- Documentation: http://www.w1hkj.org/