If you tune around the shortwave bands you’ve probably heard various buzzes, high-pitched screeches and other annoying sounds. Many of these aren’t just noise, but amateur radio digital data transmissions. These messages are surprisingly easy it is to decode using free open source software.
FLDIGI is a digital modem program for Linux, Free-BSD, OS X, Windows XP, W2K, and Vista. With FLDIGI you connect the headphone jack on your shortwave receiver to the audio-in on your computer soundcard. The GUI based program provides many digital mode choices, and even has a list of suggested frequencies to monitor along with the associated customary digital mode. While the program is designed for use with radios capable of both transmitting and receiving data, it nevertheless provides a fascinating experience for the shortwave listener to decode the data behind the “noise”.
We’ve tried other digital decoding software, and none works better than this open source alternative. Unlike some software packages, no external hardware is required beyond a stereo patch cord. No patch cord? No problem. It can even take the audio from the radio speaker and process it via the computer’s microphone! Our suggested frequency/mode for starters is BPSK31 on 14.070 MHz (upper sideband).
I have found this program last week and I can’t wait to get my radio :-)
Sweet, but does a shortwave receiver requires some kind of licence?
Shortwave receivers from companies such as Grundig/Eton or Sangean do not require a license to operate. Only when you get into buying radios that transmit do you need to take the test. The test is easy btw, you should study online for a few hours and go take it!
Thanks, awesome. Now if it will process audio from WebSDR system websites, you don’t even have to have a shortwave radio and antenna system!
http://www.websdr.org/
Going to go download it now…
Ian, I saw you had a license and wondered if you used it. Are you active or just a SWL?
-Eric
I do have a license (KB0TFS), I got it when I was a Boy Scout. I don’t have any gear, but I’m interested enough to keep the license up to date (a mighty once-per-ten-years obligation, I know…).
Great that you are covering some radio topics here. :-) It´s my main interest. At least here in Sweden you can buy transceivers without having a ham license, but you are not allowed to transmit.
But someone should of course build the receiver your self!
Eric
Just started using FLDIGI after a ham buddy recommended it over the clunky MultiPSK program Ive been using for a few years to decode HF data. The interface is a lot more intuitive and seems to work well, once you manage to get it installed properly :)
Would recommend using some sort of isolating interface between PC and radio though as a fair amount of noise can travel back down the audio cable drowning out the weaker signals on the receiver.