Posts by SWL - markro92

    Version 2.0.19



    • Fixed frequency slider input not working above 2147MHz.
    • Fixed off-by-one error in SDT (Service Descriptor Table) parsing code.

    Edit: The next update will probably be missing the dropdown box for the rolloff factor,

    further simplifying the UI.

    The rolloff factor for DVB-S1 is always 0.35.

    For DVB-S2 it's transmittd inside the BBHEADER after successful LDPC decoding.

    Second thing is interpolation before decimation, which means i can also get rid of the M&M Timing estimator, only using Gardner.

    Number three on the roadmap is changing the demapper, so that it's using a lookup table for determining the likelihood ratio for every bit of the constellation, which will be fed to the LDPC decoder. Currently i'm doing that by rotating the constellation and using I and Q values directly.

    The new approach will also simplify 16APSK and 32APSK demodulation which is hopefully working until then. I also started working on a hardware solution. I'm currently doing a prototype PCB layout which can be plugged onto an existing FPGA board (Numato Neso with an Artix7 FPGA). I'm planning to use a MAX2121 as mixer IC. I'll open a new forum thread for that when i have more to show.


    Hi, i've read your posts and i probably already know the solution for the problem. I've used signed 32-bit integers somewhere in my code. So the maximum value should be 2^31 - 1, which is 2147483647 Hz, which corresponds to about 2147MHz. I'll quickly release another version with a possible fix.

    Hi, i've updated the archive, build date is 18:40:18. Can someone tell me if the networking problem still persists? I'll try to debug this. It's kinda hard, because i never had problems. Hopefully we can narrow down the problem.

    SWL-ALAIN: i checked the download but it seems to be fine. Try deleting your browser cache. Maybe you extracted an old archive.

    The problem is as usual that for me the network stuff works. UDP really shouldn't be a problem. I'll start investigating :/

    Is someone available for a teamviewer session?

    Does recording MPEGTS to file work?

    Version 2.0.18



    • Fixed crash when changing the samplerate for LimeSDRDevice class.
    • Added TCP server for MPEGTS output.
    • Changed the TX button to a dropdown list where UDP or TCP mode can be selected.
    • Added new config options "ip_out_addr", "ip_out_port" and "ip_out_mode"
    • The MPEGTS TEI bit (Transport error indicator) is now set when LDPC decoding fails.
    • Added parser for MPEGTS SDT Tables. Program names are be shown inside the FFT Plot.
    • The Filter drowdown box for the IQ plot is working now.
    • Removed the checkbox for enabling/disabling symbol interpolation. No need to turn it off.


    G0MJW: do you have any kind of info how the pluto transmits samples via the network? TCP? UDP? some kind of header? Or are you using Gnuradio sink blocks for that? I could add a generic TCP/UDP input device with some kind of settings dialog if it helps.

    @GOMJW: normally i like the idea of giving the users maximum freedom when it comes to settings, but the majority of SDRs have fixed limits set by the manufacturer. Exceeding those limits normally doesn't do anything, it simply won't work. Of course the PlutoSDR is an exception here. I need min/max values for the UI sliders. But i could make those values adjustable by editing the device.ini. I think that's what i'll do.

    DB8TF: Wenn du M&M TED nutzt (z.B. wegen RTLSDR und niedriger Bandbreite) dann musst du bei TIming Recovery niedriger gehen mit den Gain werten. z.B. 1/256. Damping kann sogar ganz nach links. Ich muss die Standardwerte mal anpassen.

    Version 2.0.17



    • Added 16bit sample input path for devices that support it
    • Improved automatic gain control for incoming samples
    • Lowered minimum frequency to 50MHz for users of modified plutosdr firmware (user request)

    Sorry for not working a lot on this project right now, but i'll atleast release what has been done for now.

    Notes: This release contains some none-working features, these are the Decision directed equalizer,

    And the dropdown box for filtering samples in the IQ plot. AGC stuff changed the timing recovery gain settings, you should use lower values now.

    @G4XAT: please tell me if the lower frequency limit for the PlutoSDR works for you. I don't have the possibilits to test it at the moment.


    Hi, this has nothing to do with yor CPU, i'm having the same problem. The PlutoSDR uses libiio, which is a piece of software by Analog Devices handling all the USB stuff. but the problem is, that i need to poll the data, which means, that i need to ask it for a new chunk of samples. If i don't manage to do it frequently enough, there are lost samples. And that's the worst thing that can happen for a DVB-S demodulator...

    There are many reasons for this problem. It can be the operating system not scheduling the thread often enough which does the polling. That's the case on high CPU load, or if there are peaks in CPU usage. Of course, this is an important problem, which i need to find a solution for. A temporary solution could be using lower samplerates. That improves things a little, but it doesn't fix the problem. I recommend other SDRs at the moment until i come up with a solution. As far as i know, the PlutoSDR and LimeSDR have this problem. I'll keep you posted on this.