PyFT8 1.0.0

FT8 Decoding and Encoding in Python with test/loopback code

PyFT8

FT8 Decoding and Encoding in Python with CLI and research code

This repository contains Python code to decode and encode (all the way to audio) FT8, plus a minimal Command Line Interface for reception, and a nascent set of research code.

Motivation

This started out as me thinking "How hard can it be, really?" after some frustration with Windows moving sound devices around and wanting to get a minimal decoder running that I can fully control.

My current aim is to push the low SNR performance whilst using only one time/frequency grid and no time-domain processing.

Code I'd like to highlight, all in 100% Python:

• LDPC using just three 5~8 line functions and running 250 us per iteration on a Dell Optiplex
• Ordered Statistics Decoding in about 60 lines of code & similarly fast (not measured yet)

Uses

I use this code for my own hobby-level reseearch into FT8 decoding and Python coding techniques, and I'm also building a browser-GUI station controller (image below) which has an FT8 transceiver integrated within it. You can see that here but note that it's focussed on my station, i.e. ICOM-IC-7100 with an Arduino controlling antenna switching and magloop tuning.

Contents

[being written]

• Overview of main code and decoding process
• Testing and research code

Installation

This repository is usually a little ahead of the releases I send to PyPI, but you can pip install it from there and just use the Command Line Interface (which can also transmit individual messages) if you want to.

Install using:

pip install PyFT8

And to run, use the following (more info here)

PyFT8_cli "Keyword1, Keyword2" [-c][-v]

_{* where keywords identify the sound device - partial match is fine - and -c = concise, -v = verbose}

Otherwise, please download or browse the code, or fork the repo and play with it! If you do fork it, please check back here as I'm constantly (as of Jan 2026) rewriting and improving.

Limitations

In pursuit of tight code, I've concentrated on core standard messages, leaving out some of the less-used features. The receive part of the code doesn't (yet) have the full capability of the advanced decoders used in WSJT-x, and so gets only about 60% of the decodes that WSJT-x gets, depending on band conditions (on a quiet band with only good signals PyFT8 will get close to 100%).

Acknowledgements

This project implements a decoder for the FT8 digital mode. FT8 was developed by Joe Taylor, K1JT, Steve Franke, K9AN, and others as part of the WSJT-X project. Protocol details are based on information publicly described by the WSJT-X authors and in related open documentation.

Some constants and tables (e.g. Costas synchronization sequence, LDPC structure, message packing scheme) are derived from the publicly available WSJT-X source code and FT8 protocol descriptions. Original WSJT-X source is © the WSJT Development Group and distributed under the GNU General Public License v3 (GPL-3.0), hence the use of GPL-3.0 in this repository.

Also thanks to Robert Morris for:

• basicft8(*1) - the first code I properly read when I was wondering whether to start this journey
• weakmon - much good information

(*1 note: applies to FT8 pre V2)

Other useful resources:

• W4KEK WSJT-x git mirror
• VK3JPK's FT8 notes including comprehensive Python source code
• Optimizing the (Web-888) FT8 Skimmer Experience Web-888 is a hardware digimode skimmer currenly covering FT4/FT8 & WSPR, part of the RX-888 project.
• WSJT-X on Sourceforge
• Declercq_2003_TurboCodes.pdf
• Q65 coding discussion
• G4JNT notes on LDPC coding process
• FT8Play - full details of message to bits etc
• Post about ft8play
• FT8_lib
• Decoding LDPC Codes with Belief Propagation | by Yair Mazal
• 'DX-FT8-Transceiver' source code, the firmware part of the DX-FT8 Transceiver project
• 'ft8modem - a command-line software modem for FT8' Matt Roberts' implementation as an FT8 modem with a CLI interface, including source code (C++ and Python) (bottom of page)

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