Posts by SWL - markro92

    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.

    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.

    Ok, very good :) nice CPU. Maybe i should upgrade, too. Still have a good old Haswell CPU (5820K).

    In this case, i really think 30MSym/s should also be doable. Thanks for the feedback :)

    Which SDR are you using by the way?

    Edit: Intel says you have a Mobile CPU? is that true? I feel my PC is running on a potato right now :D

    Hi, for performance reasons, you could try to reduce the number of RRC taps to 32, and disable the update of CMA coefficients. That's the Update coeff. checkbox on the right. Can you show me the statistics view? Click on Debug -> Debug Worker Stats.

    Glad it seems to work. how fast do buffers fill on the bottom right of the window? which CPU model are you using?

    Looks promising :)

    You can save the output by clicking on the 'File' button in the 'Network / Network' section. It will ask you for a location and filename.

    Alternatively, streaming is right below that. UDP / TCP are supported. VLC URLs are for example for UDP: udp://@:8888 or for TCP: tcp://

    Hi, you can do that yourself in the config file. There is a setting called 'sr_max'. You can also edit the presets there.

    However, right now even 10MSym/s is ambitious. I've received tv feeds with 9600ksym/s before. It works with high SNR, otherwise demodulating and LDPC decoding takes too long. I'm partially rewriting the demodulator at the moment. There is a lot of potential when it comes to optimizations, but 30MSym/s seems out of reach for a software-only solution (I'm not saying it's impossible). By the way, thanks for your kind words :)

    M1CTK: do you have an AMD CPU and is is crashing?

    It should run on AMD CPUs, but i'm not able to test it. I'm only using instruction sets at the moment supported by both CPU families.

    Can you give ne a screenshot of your titlebar if the program starts up? otherwise Download CPU-Z and give me a screenshot of the first window, where CPU Name and Feature Flags are displayed. It should support up to SSE4.1. Of course i also want people with recent AMD chips to run this.

    Ok, sorry for not finding the issue earlier, i'll look into it. There are a few spots in the code that i could have overlooked. Is it just the FFT display? The actual reception should work if you rightclick and try to find the transponder by accident while only using the IQ plot. Not sure if you know what i mean. FFT is bugged, rest should work as is. I'm sure that i fixed the calculation of filter coefficients, so reception should be fine regardless.

    You are correct with 4295MHz. To be exact, the maximum frequency seems to be 2^32-1 (two to the power of 32), which is 4294967295Hz.

    @Iz5tep: maybe. The modulation is quite different, though.

    Actually, the roadmap is as follows:

    1. complete the demod gui, which is roughly:

    1.1 Making the demodulator more robust

    1.2 Adding 16APSK and 32APSK modcodes.

    1.3 Support for receiving multiple transponders at once

    1.4 Adding TX capability with LimeSDR Mini and PlutoSDR, so that it can also be used as a modulator.

    2. Creating a PCB Layout and implementing the Demodulator in VHDL. Will be running on a FPGA with USB and Ethernet interfaces.

    It will also have a step-up converter to power the LNB (LNBH-29), mixer is MAX2121 (need to find out if i can tune lower than 10700MHz), and some ADC from Linear Devices (something around 100MHz with 10bit resolution)

    3. Implementing more Standards, like DVB-S2x and DVB-T/T2

    Version 2.0.20



    • Support for input frequencies up to 6GHz and theoretically more.
    • The resample worker thread now completely uses fixed point math.
    • Removed the checkbox for DC correction, it's now always enabled.
    • Removed M&M timing estimator, Gardner algorithm works better anyway.
    • Added 2x upsampling before downsampling due to the Gardner algorithm requiring 2 samples per symbol minimum.
    • Added TCP input device for streaming samples over the network. For example, you could connect to a GnuRadio TCP Server Sink.
    • Added support for dummy frames to the demodulator.
    • Added experimental support for generic stream encapsulation to the demodulator (only continuous stream).
    • Fixed crash when recording files larger than 1GiB.

    Known bug: Closing the TCP output connection causes a crash when recording generic streams.

    The only Transponder that i could find and which is currently supported is the NRK DAB Mux on Intelsat 10-02 - Thor 5/6/7 @ 1° West.

    10720 V
    Multi 171
    5400 3/4 DAB NRK

    Support for Generic streams is not complete this feature needs more work. But when you are recording to a file, there should be IPv4 packets inside. There will be a possibility in future versions to filter Multiple Input Streams.


    Hi, i'm planning on releasing a new version next weekend. Main improvements will be:

    - Raw sample input via TCP to be able to support GnuRadio sinks or sample input from other network devices

    - Upsampling before downsampling to get rid of the M&M Timing Estimator, only using the Gardner algorithm

    - Support for DVB-S2 Dummy Frames

    - Support for Generic Stream Encapsulation (for instance radio stations put into ethernet frames and extracting network traffic)

    - Automatic selection of filter parameters (rolloff factor)

    Hi, i just updated the binary, please re-download.

    The build date is Jul 4 2020 13:19:24.

    SDRPlay works fine for me, but i noticed that i commented out the

    code writing the number of LDPC iterations to the console window

    which could be very confusing :D i was about to implement an alternative

    solution and forgot to re-add it for the release. Sorry for the inconvinience.

    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.