Software DVB-S demodulator

  • Sì, qualche giorno fa manualmente ho cambiato la posizione dell'lnb installato sulla parabola satellitare. Oggi ho cambiato la polarizzazione per mezzo della tensione di alimentazione: banda stretta a 12 volt, banda larga a 15 volt. Grazie

    il tuo LNB in posizione verticale con 18 volt con poco di inclinazione verso orizzontale ma poco un 1cm dal verticale

  • Dear om:

    I am working (and playing) with the last version. with Adalm-Pluto. But I have one qestion: not is possible set Modmode fixe to QPSK 4/5 to see only the QO-100 DATV?

    73,s de Jabi, ea2aru.

    Hi Jabi, your question is confusing, I don't understand to set Modmode fixe to QPSK 4/5, the question about Adalm-Pluto is all automatic, if you are using Minitiune V2 there is no parameter to set, I think your question is that you are not receiving QO100.

    73 Tony ik1hgi

  • Hey Guys,

    Have anybody the same problem that when tcp-stream is using the VLC-Player frozes after 2 sec picture showing. Audio works all the time. Its not a permanent problem (some signals works correctly, beacon) but some signals frozes everytime when I want to decode. Test it out with some versions of DVBS-GUI and VLC-Player.

    Its curios because i think it have not be to make a change between beacon and other signal. Beacon is working correctly...

    73 de DL1DJH

  • Hi Dominik,

    I am new to the this forum so have my excuses for silly question.

    I am a user of QO100 satellite using an home made sdr transceiver running on Linux in the narrow band.

    I am know trying to make a receiver working in the wide band place detecting the TV channel but ... my big problem is that that producing the demodulator is out of my capabilities , i tried to use the leandvb but it showed lot of problems trying to integrate the code in my application. When i saw your thread i tried to use the given address to download your version it did not work.

    Is it possible to have your code?

    Thanks in advance for your attention.


  • Hi George,

    Thanks for answering, i am not afraid of writing C++ statements but unfortunately my knowledge of digital TV encoding is almost inexistent, actually i have been searching on web what you meant with MER. I did not consider the TCP option because my goal is to produce a stand alone receiver connected to the antenna. Also the MER suggested by you for what i understood is a tool just for checking the quality of the received signal. I saw the offer made by Dominik and concerning an already written and checked decoder which was promising.

    Do you have an idea if still available and eventually how?


  • George , Yes i believe i got what is a mer (modulation error ratio) via a constellation graph but is not what i am looking for which is, possibly, a DVB_s2 decoder to integrate with my software then may be also a mer could participate.


  • Hi all and seasons greeting . I'm looking for the last version link for DVB-S demodulator   . Thanks & 73

    Hi St2nh Nader. The link is (page 40 this thread):

    73 !

    Version 2.1.0



    • Added support for 16APSK and 32APSK modcodes
    • Fixed demodulator using wrong modcodes in ACM/VCM mode
    • Fixed a crash occuring while cleaning up buffers on program exit
    • Fixed wrong scaling of TCP input samples using the F32 format
    • Fixed IQPlot imaginary axis being flipped
    • Removed QCustomPlot dependency
  • Hi all. The software is working quite well with a NOOELEC sdr stick and a 80cm dish. Signals must be nearly as strong as the beacon to decode. So far I am able to decode 1500ks to 250ks in QPSK. This software is great for getting started in DATV on QO-100. :thumbup::)

  • Hi!

    I'm having issues receiving DATV signals from WB transponder.

    My current set-up is:

    85cm dish

    Opticum LSP-02G LNB (-> supply voltage is 18.5V)
    Adalm Pluto and/or RTL SDR USB Stick

    I tired with SDR Angel and with this software. But the video and audio is mostly not stable...

    I played with the BB gain setting and the current setting gives me the best result.

    Is there anything else I could optimize in the settings to get a better signal?

    On NB transponder my SNR is 31 dB (CW beacon) - is that enough for receiving DATV signals via WB?

    Thanks + 73


  • i have the same problem with picture freeze after a second but audio still works

    any hints what it may be?

    beaon decode works fine but i see that on several ham signals its difficult to find a lock

    and even if locked not always a picture is shown