Software DVB-S demodulator

  • @markro92 Great Software, But it seems DVBS1 is not working anymore..

    Tested on 3 different locations with different computers and setup's

    Tested on 144.600, 436 Mhz and 1255mhz.

    Use RTL stick as receiver.

    DVBS2 works simple and perfect.

    250 KS up to 2Ms..

    But switching to DVBS1 i get the constalation perfect but no sync..

    not even more than 1.

    I use 500KS FEC 2/3 DVBS1 H264... for testing...

    Can you confirm that DVBS1 should work?

    Best regards...


  • Works for me :)

    Tested with 'Antenne Düsseldorf' TP on Astra 3B @ 23,5°E.

    FEC 7/8

    Well the thing is, DVB-S1 is horrible to use at the moment, because it's kinda unclear.

    Version 2.0.21 will finally have blindscan, but until then:

    Set the FEC, and then click on "DVB-S1 Symbol Skip", and combine that with rotating the constellation with the Derotate slider. There is only one combination that works. SO you basically click a few times onto the skip button, if it doesn't work, rotate the constellation 90 degrees and skip symbols again until it works. In that case the sync_confidence value will go up and stay high without flickering.

  • So, an update on higher symbol rates, no luck with QPSK 9/10 on 27500 and 29500 MSym/s samples. Constellation looks noisy and nothing seems to be succesfully decoded although there are locks sometime.
    Any advice what could be better tweaked? Also, is there a frequency offset debug info hidden somewhere?

  • Hi, there are a few things, maybe there is an error calculating filter coefficients, can you change the symbolrate slightly? maybe to 29501?

    This is clearly a problem with timing recovery or earlier stages than that. Can you also try to increase the input gain? it seems very low. The FFT should atleast be yellow-ish. btw, there is no frequency offset info, but that's not the problem here. I did a lot of optimizations to reduce CPU load, i could give you a new version tomorrow. But don't expect too many new features yet.

  • DL3DCW: There is a config option to specify PlutoSDR Network devices.


    # iio_net_contexts: IP addresses of PlutoSDR devices.

    # Multiple devices can be specified as a space-

    # separated list.

    In the config.ini file the corresponding line looks like this:

    iio_net_contexts =

    edit: i haven't tested this in a while, but it should still work. I'll check.

  • Hallo Zusammen,

    ich habe folgendes Problem!

    WB empfangen mit Pluto und als SW DVB-S2 Demod GUI Version 2.0.15

    Ich kann das Signal empfangen und auch abspeichern in eine Datei. Dies kann ich dann auch im VLC-Payer ansehen. So weil so gut.

    Ich möchte aber mit dem VLC-Player direkt mitsehen, bekomme das aber nicht hin.

    Kann mir mal jemand sagen was ich da machen muss??

    Gruß Ulrich

  • Hallo Ulrich,

    Im Recording / Network Panel befinden sich unter dem Dialog zum Aufnehmen auch EIngabefelder für IP/Port und das Protokoll.

    Standardeinstellung ist, Port 8888, Protokoll ist TCP. Im VLC Player wäre die entsprechende URL dann tcp://

    Für das UDP Protokoll wäre das dann udp://@:8888



    Edit: Ich sehe gerade, dass Sie version 2.0.15 nutzen, da gab es glaube ich nur die UDP option. Ansonsten, Version 2.0.21 ist die aktuelle.

  • Hi Tony,

    ^ There, as always.

    I forgot to write a post for it, because the forum didn't let me post messages a few weeks ago.

    There were only minor changes anyway.

    At the moment i'm working on a bigger release (v2.1) which i plan to release mid December.

    Right now i do changes to the demodulator, and a partial rewrite of the whole codebase.

    Main features will be:

    - Receiving multiple transponders at once

    - Scanning a frequency range for transponders and detecting settings automatically

    - Saving common transponder locations and grouping them

    - 16APSK and 32APSK support

    - Displaying the Signal to Noise Ratio

    - Increasing performance by supporting AVX for some of the worker threads.

    - Linux Release (probably Debian or ArchLinux)

    Optional Features:

    - OpenCL support, mainly for offloading LDPC decoding to the GPU.

    - Port to Raspberry PI 4

  • grazie SWL - markro92, ho scaricato il gui-2.0.21 e ho trovato difficile con la barra di scorrimento trovare sempre lo stesso punto, come puoi vedere immagine, video niente ho messo il 20.20 la stessa cosa !! provato con la chiave RTL-SDR tutti regolari, gui-20-19, gui-20-20 gui-2021, ora non capisco se è il mio problema pc, i3 coreldro 16 ram, non codifica.

    73 Tony IK1HGI

  • ciao sto usando DVB-S2 Demod con 2832 RTL stick e non ho problemi, ho anche un RSP1A ma non funziona .. parte il prg ma alla fine della pagina di inizializzazione dice dispositivo disconnesso cosa posso fare? qualcuno usa questo oggetto? tnx Marcello

    Ho dimenticato che sto usando la versione 2.0.21

  • IK1YW Hey,

    Tested with the rsp and its works...dont forget this sollution!!!!

    sdr-play boys to remember... if you have problems...

    yes you will;):D:D:D:D:D

    Install : API/HW Driver 3.07

    Install it in the same map were you placed the DVB-S Demodulater...

    open the map and you will find a "SDRPLAY" map

    Open it...

    Open the map API...There you will find x64 and x86....(64 and 32 Bit pc!!!)

    open the map and find "sdr_play.api and lib"

    Copy both to the dirctory of the DVB-S DEmod

    Greeting and succes ON7KEC