I want to take a non demodulate audio signal from webSDR portals (http://www.websdr.org/). In order to try to feed these in DREAM DRM Radio software or GNURADIO.

Could be cool almost try it for educational purposes.

A Youtube video very informational about I/Q could be see at: https://www.youtube.com/watch?v=h_7d-m1ehoY&t=150s


Any radio in upper-sideband (USB) mode is effectively a frequency down-converter, WebSDR included. That is, USB simply shifts frequencies down, not changing the modulation other than the frequency shift. This is why digital modes such as PSK31, JT9, WSPR, etc can be implemented by an audio connection to an ordinary USB radio.

So simply tune in the frequency of interest in USB mode, and feed the resulting audio into GNU Radio. If you want it in IQ form you can use either the Hilbert transform block, or use "float to complex" and simply ignore or filter out all the negative frequencies, which will be a mirror of the positive frequencies.

  • $\begingroup$ Does USB here mean the usb everyone knows, or Upper Side Band? $\endgroup$ – NoBugs Jan 31 '20 at 1:30
  • $\begingroup$ Yes. (Extra words to meet minimum comment length.) $\endgroup$ – Phil Frost - W8II Jan 31 '20 at 4:10
  • $\begingroup$ Yes upper side band or usb plug in sdr? $\endgroup$ – NoBugs Jan 31 '20 at 4:42
  • $\begingroup$ Awesome Phil I will try to decode ft8 first and then will try with DRM. I will report in the future over here the results. Thanks so much. $\endgroup$ – Hender Jan 31 '20 at 15:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.