Software DVB-S demodulator

  • Hallo Marco,

    ich habe gerade nochmal mit der LimeSuite einen update durchgeführt. Ich hatte aber schon die aktuelle Version der Firmware drauf.

    Ich habe auch gerade mal mit der Version 2.0.8. probiert, die findet jetzt
    leider den Lime USB auch nicht mehr.

    SDR-Console läuft aber weiterhin einwandfrei mit dem LimeUSB.


    Matthias DD1US

  • SWL - markro92

    I read on the BATC chat that, since version 02.8 of your software, the LimeSDR-Mini firmware needs to be upgraded to the last version: is it correct?

    it's not a problem for me as I have never been able to make it decode a signal...neither Lime mini or hackrf or rtl-SDR dongle...

    but for others maybe it's important to know.

  • Version 2.0.10



    • Added Support for SDRPlay (only tested with RSP1A, Channel A for now)
    • Added 2,8MHz and 3,2MHz Bandwidths for RTLSDR. They not always work because of USB2.0 limitations, but some people have luck with that, so i've put them in.
    • Made the FFT Plot detachable from the main window.

    Known issues (to be done in next version):

    • Demodulator is losing lock too often
    • SDRPlay device cleanup code crashes the application

    The next version will be a major update (2.1.0) and will enable multi-signal reception along with some GUI changes. Maybe ready in one or two weeks.

    Edit: maybe i'll also re-add the equalizer (CMA)

    That's performance hungry, but it should reduce reflections and non-linearities in the receive channel.

  • Try with my RSP1A to decode the beacon with no success. Compared settings with the settings I found in this thread but not sure if correct. Mostly I get only a few dots in the IQ Plot. But with the settings shown on the screenshot I get more or less a circle or sqare, buffer raise until max reached and programm crash.

    PC is a Laptop with i7 qcore running Win10 64Bit.

    Any idea/hint which settings I need to change to get it working.



  • DH2VA , using a offset dish 70x80cm (w*h) test was done with a non modified Octagon Optima OSLO single LNB, tried as well with same LNB Type but modified with a TCXO.

    Bias-T with 18v to get correct polarisation for WB. About 5m cable and RSP1A. Free sight to satellite, no trees etc in front of Antenna. Used NB CW Beakon to get best RX result.

  • DH2VA: i can't see a problem with the settings, everything else seems to be fine. So i think that your signal is a bit too weak. Are you able to receive it with other equipment? Also try lowering the Carrier Recovery Gain setting a bit, to about 1. That should help with noisy signals, but i doubt that this is the problem

  • Unfortunately I have no other supported hardware then the RSP1A.

    Tested with carrier recovery gain set to 1, for a while I get nothing int he IQ Plot only a few random drops and sometimes I get a short flap of blue circle with less dots in the middle. After few minutes I then get same picture as above.

    Maybe signal is a bit weak, when I look on this in SDR-Console I see the WB beakon only with about 5-6db over noise.

    As well I saw that I can read the FEC values in the drop down. But this seems only cosmetic item.

  • A great project, thank you!

    I was able to decode the first video with 250Ks!

    The software works, but is still difficult to use.

    The receiving system is a SDRPlay2pro with 60cm offset antenna + GooBay LNB and external TCXO.

    73 de Peter, DL1AVX

  • DG7YEO Have you corrected the LNB skew? It should not be fully upright but rotated a bit. The little things can be decisive now.

    Skew can be optimized to switch to 18V (H) and *minimize* the CW beacon. Then the WB beacon should be optimum (minimizing CW beacon give clearer result).

  • DH2VA, hope so, did it on the NB when I installed the dish. Take the values from for Badr4/5/6 and then optimised by going left/right up/down till I had the strongest CW Beakon. Of course using 13,8V for vertical polarization at that time.

    But could retry the skew the way you suggested next days.

    On pictures you see my dishes, infront the 40cm for Astra, middel 33cm currently with TCXO modified Octago, last one the 75x80 with non modified Octagon. The last one I used for the WB tests, but when I receive my ordered TX equipment for NB I will replace this with a BaMaTech Duobandfeed, so no WB at that time.

  • hello , dg7yeo

    Can you please test the mueller and muller filter instead of gardner filter for the beacon. center your frequency from beacon as good you can .

    keep also your eyes on actual symbolrate (under middle)

    when symbolrate is going higher , slightly go 1 symbolrate up and down. (stabilisation and reset)) time recovery

    the symbolrate must stay around 2000

    than try carier recovery .start with loop damping full to the right side

    give then gain intil you see constellation. then lower to 0 loop damping (ful left side)

    keep gain to loop gain to about 3... enable it...

    then as last step , choose the fec and then enable also the ldpc ...

    tip ,for all lower symbolrates use the gardner filter

    it is always best when you start , do not enable the ldpc and also no enable carier.

    i hope this info will help you

    73 , nico

  • DG7YEO please don't confuse AZ/EL (left/right/up/down) with skew. The latter is rotating the LNB in its mount like a cloc. The reason for doing so is that horizontal and vertical is defined by the satellite's local coordinate system and as it is not straight south from us, we have to rotate our LNBs a bit (13deg for central europe).

    Please don't ask me about direction.. I always explain it wrong and after all the alignment is straight forward and non-ambiguous.

  • DG7YEO & DH2VA

    Skew angle (in EU) is conter clock wise (CCW). That means: You "sit" in the dish and are looking towards the satellit (in the sky) over your LNB. From this point of view turn it 13° counter clock wise. ;-)

    73 de Johannes

  • DL5RDI, that is how I understood it. But take a while for me to know from which site to look ;-)

    I optimised the Skew like suggested from DH2VA and tested with actions descibed by ON7NDR and was at least able to get a video output, is still not clear an IQ Plot still don't look ok, as well buffer raise over time but not as fast as before. So it will look like pictures 2a or 2b anyway pic 3 show partly success, believe I have to low SNR to get a clean signal.

    Anyway thank you for all the support here, was very helpfull for somebody new in DATV