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Software that allows a sound card to be used as a data modem / From Wikipedia, the free encyclopedia

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Fldigi (short for Fast light digital)[4] is a free and open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem. The software is mostly used by amateur radio operators who connect the microphone and headphone connections of an amateur radio SSB or FM transceiver to the computer's headphone and microphone connections, respectively.[5][6]

Quick facts: Developer(s), Initial release, Stable release...
Developer(s)Dave Freese (W1HKJ), et al.[1]
Initial release2007
Stable release
4.1.19 / 24 June 2021; 19 months ago (2021-06-24)[2]
Written inFLTK, C, C++
Operating systemWindows, macOS, Linux, Android, FreeBSD[3]
PlatformIA-32, x64, IA-64, armel, armhf, mips, mipsel, PowerPC, s390, s390x, SPARC, Raspberry Pi
SizeAbout 6.5 MB
Available in7 languages
List of languages
English, Italian, Spanish, French, German, Polish, Dutch
TypeAmateur radio and DSP
LicenseGPL version 3.0

This interconnection creates a "sound card defined radio" whose available bandwidth is limited by the sound card's sample rate and the external radio's bandwidth.

Such communications are normally done on the shortwave amateur radio bands in modes such as PSK31, MFSK, RTTY, Olivia, and CW (Morse code). Increasingly, the software is also being used for data on VHF and UHF frequencies using faster modes such as 8-PSK.

Using this software, it is possible for amateur radio operators to communicate worldwide while using only a few watts of RF power.

Fldigi software is also used for amateur radio emergency communications when other communication systems fail due to natural disaster or power outage. Transfer of files, emails, and FEMA ICS forms are possible using inexpensive radio hardware.[7][8][9][10]