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.
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Read our verdict in the software roundup.
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