What is Fldigi in Amateur Radio?

 Some time back we have a Google Meet on Fldigi in our LEO Satellite Group, conducted by VU2TUM. Thought of brushing it up once again when VU2NXG told me yesterday that Fldigi can be used for RTTY mode, though I am yet to try it out. Fldigi known in full as Fast Light Digital, is a cross-platform modem application which supports most of the peer-to-peer digital modes used on amateur radio bands with live keyboard. Fldigi allows the sound card of a computer to be used as a simple two-way data modem. It is a free and open source program which can be downloaded from sourceforge.net. Fldigi supports CW or Morse Code operation using a computer keyboard and Radio Teletype known in short as RTTY and many other modes which I am not familiar with. The program was written by W1HKJ who has also authored several other amateur radio programs.



There is a nice Beginners' Guide to Fldigi written in simple language. But to make the best use of the program, one has to read the Online Documentation. Fldigi is available for multiple operating systems of your choice like FreeBSD, Linux, OS X and Windows. Though I have tried all these operating systems at some point of time, currently I am mostly a Windows user. I have used FreeBSD the least and Linux and OS X for fairly long periods in the past. With Fldigi, the computer does the work of modulator-demodulator or modem as well as controls the transceiver - CAT or computer assisted transceiver control. It provides for change of operating modes, easy tuning and prearranged messages. I have heard one of my friends who is not a regular CW operator, checking into local HF net with an excellent CW signal, using keyboard and not the key or keyer!

For my FT-710 radio, the CAT control cable is nothing but a simple USB printer cable, with type A plug going to the computer and type B plug going to the rear side of the radio. FT-710 also has an additional RTTY/Data port which needs a different cable and I do not have it. Connection between computer and the radio is considered to produce a "sound card defined radio", like the software defined radio, which I am currently more familiar with, as my radio is an SDR. Bandwidth of the "sound card defined radio" is limited by the sound card's sample rate and the external radio's bandwidth. An advantage of digital communications using Fldigi is that world-wide communication is possible with much lower powers than what is needed for conventional voice modes like single sideband or SSB.

 

 

 

 

 

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