Who else is getting started with GNU Radio?

Discussion in 'Software Defined Radio (SDR)' started by N0NB, Jan 24, 2019.

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  1. W6RZ

    W6RZ Premium Subscriber QRZ Page

    Cool. Be aware that "reboot" does an immediate reboot and can be a little surprising since it doesn't need sudo (if you're the only user on the system).
  2. G4HYG

    G4HYG Ham Member QRZ Page

    It sounds like you only have one audio channel or Mono selected. It needs I and Q audio channels sent to Left and Right (or Right and Left depending on the receiver) for the software to display the correct spectrum.

    if you only have one audio channel or Mono selected then it works exactly like a direct conversion receiver and the software displays both sides of the spectrum together as a mirror image about the DC point.

    If you are using it with Windows check the sound card audio settings as external cards often get set up as a default mono microphone and need changing to DVD quality stereo.


    Chris, G4HYG
  3. N0NB

    N0NB Ham Member QRZ Page

    Thanks, Chris.

    That is what I was wondering. Before I tried it a couple of months back I checked the continuity of the audio out cable back to the board for each contact on the 3.5mm plug. I am using a Xonar U7 and everything sound related in Debian Buster (Linux) indicates the microphone input is stereo. I suppose I'll need to do some testing.
    Last edited: Feb 3, 2019
  4. N3HEE

    N3HEE Ham Member QRZ Page

    Is there a way I can get GNU radio to play back I/Q files that I have recorded from my Flex 6600M ? I've tried playing around with GQRX without any luck.
  5. W6RZ

    W6RZ Premium Subscriber QRZ Page

    Gqrx expects an IQ file of float values. 4 bytes of I followed by 4 bytes of Q and so forth. Here's a sample file you can test with. It's upper sideband SSB at 1.92 Msps. It's generated from GNU Radio, so there's no noise. 773,314,880 bytes. Be sure to right click on the link.


    If you can upload a Flex IQ file somewhere, I can take a look at it.
  6. N3HEE

    N3HEE Ham Member QRZ Page

    Thanks! I'll try your file and I will post one of my files tonight for you to try. -Joe
  7. N0NB

    N0NB Ham Member QRZ Page

    Since getting an RTL-SDR.com V3 dongle and an SDRplay RSPdx within the past two weeks I tried both with Cubic SDR and HDSDR in Linux and W10 and get the same effect of everything mirrored from the P3 IF OUT port. Connect both to an antenna and everything was proper. From what I've been able to glean any program intended to be used as a panadapter piggybacked off the P3 needs to take this into account and process the resulting data stream differently. That said, I've not found any official documentation on what kind of spectrum the P3 IF OUT port presents and I've no other radio available with an IF OUT type port to check against.
  8. KT1F

    KT1F Ham Member QRZ Page

    Fair enough if you're building from source for the learning experience or because you want the very latest but if you just want to get GNU Radio installed and working then the PPA repositories have quite recent builds. I tried it a few months ago and it installed painlessly in my laptop running Ubuntu 18.04.


    I don't think had that official PPA until a few months ago.

    I got enthused a while ago and worked through these https://greatscottgadgets.com/sdr/ . I don't have a HackRF but I was able to get the exercises going with a cheap RTL. I now have have an AirSpy discovery and want to try to get back into GNU Radio using that. I don't really know what I want to do with it. I mostly just want to understand digital signal processing better. I probably have enough of a math understanding and background to get through it but even so, it's quite a learning curve.
    Last edited: Apr 11, 2020
  9. KI7HSB

    KI7HSB Ham Member QRZ Page

    What's GNU?

    Nuthin'... What's GNU with YOU?
  10. KT1F

    KT1F Ham Member QRZ Page

    Don't worry, it's not Unix.
    KI7HSB likes this.

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