Fldigi is a modem program for most of the digital modes used by radio amateurs today: CW, PSK, MFSK, RTTY, Hell, DominoEX, Olivia, and Throb are all supported.
It can help calibrate a sound card to a time signal and do frequency measurement tests.
Key Features
- BPSK and QPSK 31, 63, 125, 250 (both), and 63F and 500 (BPSK only)
- PSKR 125, 250, and 500
- CW speeds from 5 to 200 wpm
- DominoEX 4, 5, 8, 11, 16 and 22; also with FEC
- FSQ
- Hellschreiber Feld Hell, Slow Hell, Hell x5/x9, FSKHell(-105) and Hell 80
- IFKP
- MFSK 4, 8, 11, 16, 22, 31, 32 and 64; most with image support
- MT63 500, 1000 and 2000
- OLIVIA various tones and bandwidths
- RTTY various baud rates, shifts, nbr. of data bits, etc.
- THOR 4, 5, 8, 11, 16 and 22
- Throb and ThrobX 1, 2, and 4
- WWV receive only – calibrate your sound card to WWV
- Frequency Analysis receive only – measure the frequency of a carrier
Fldigi can also control a transceiver using Hamlib or RigCAT I/O, perform online or cdrom QRZ queries, log QSOs with the built-in logbook or Xlog, and send reception reports to the PSK Automatic Propagation Reporter.
This is free and open source software.
Website: www.w1hkj.org
Support:
Developer: Stelios Bounanos, David Freese
License: GNU General Public License v3.0

Fldigi is written in C++. Learn C++ with our recommended free books and free tutorials.
Related Software
| Ham Radio | |
|---|---|
| WSJT-X | Basic amateur radio communication using very weak signals |
| Tucnak | Ham radio VHF/HF contest logbook |
| QLog | Amateur radio logbook |
| Dire Wolf | AX.25 packet modem/TNC and APRS encoder/decoder |
| Qtel | Qt EchoLink client |
| wfview | Controls icom ham radios |
| Flrig | Transceiver control program |
| Fldigi | Modem program for most of the digital modes |
| TrustedQSL | Tools for digitally signing Amateur Radio QSO records |
| klog | General purpose ham radio DX logging support |
| CQRLOG | Advanced ham radio logger |
| Xastir | X11 graphical APRS client |
| ADIF Multitool | Validate, modify and convert ham radio log files |
| AetherSDR | Linux-native client for FlexRadio Systems transceivers |
| Xlog | Logging program for amateur radio operators |
| PyQSO | Contact logging tool for amateur radio operators |
| Not1MM | Ham radio contest logger |
| JS8Call | Software using the JS8 digital mode |
| FreeDV | Desktop application for amateur radio operators |
| CHIRP | GUI tool for programming ham radios |
Read our verdict in the software roundup.
Explore our comprehensive directory of recommended free and open source software. Our carefully curated collection spans every major software category.This directory is part of our ongoing series of informative articles for Linux enthusiasts. It features hundreds of detailed reviews, along with open source alternatives to proprietary solutions from major corporations such as Google, Microsoft, Apple, Adobe, IBM, Cisco, Oracle, and Autodesk. You’ll also find interesting projects to try, hardware coverage, free programming books and tutorials, and much more. Discovered a useful open source Linux program that we haven’t covered yet? Let us know by completing this form. |

