Software DVB-S demodulator

    Quote from F4FDW

    DVBS2gui funziona anche su Linux?

    73 F4FDW

    Once again I tested the pluto with linus thanks to the help of Nico for his care to be able to understand the program leandvb install video ubuntu 18.04 for qo-100 datv in real time video / audio with mplayer this is a guide how to use and install "leandvb" software for experimenting with regular rtlsdr for receiving oscar 100 datv on a normal 9750 lo pll universal lnb and the datv beacon as an example in my video ..... good luck Nico on7ndr ..... de on7ndr Nico

    https://www.youtube.com/watch?v=NwOeXf-ptqg&feature=youtu.be



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    73 Tony IK1HGI

    Hi All

    I downloaded the latest version on my Windows 10 (1903) PC.

    As soon I start the software, it will run 2 sec and than it freeze. The software will find my SDRPlay Duo 2 and I'm able to "open" the device.


    No idea why :(


    It's always very frustrating that after a Windows 10 Update nothing is working anymore which is related to hamradio :(


    73 de HB9RYZ

    Wolfgang

    Hi All

    But I was not able to see any DATV Video with this software and the VLC-Player :(

    Is there a complete Quick-Quide how to do so?


    Why are developers in the HAM-Community never never write manuals how to use there own software - this is the missing USP.

    And let the users share how it works. Just a Quick-Quide in a PDF for dummies would be engough. But every time I have to collect all information our and our in the Internet - its just a waste of time for everybody.


    73 de HB9RYZ

    Wolfgang

    here a guide of the program dvb gui I hope that for you and useful for some details as presented on7kec Grussen images are all ok, only in this system it takes a lot of pasinzae to understand SR ok sivedere when sitrasters, the FEC and in automatino only of set up manula when you see the signal all here (( VLC comando media udp://:@8888 ))))

    Greetings Tony IK1HGI


    https://www.dropbox.com/s/9wan…software%20guide.pdf?dl=0

    Hi All!

    I have the stream decoded. But problems with "buffers". The value is constantly increasing and after a few minutes reaches 8192 and the program closes.

    If I disable "LDPC decoding", everything is normal.

    Computer is Intel Core I7-2670QM 2,2 GHz.

    Any ideas? Thanks!

    @G0MJW: yes, that's exactly what happens.

    @R0AU: If LDPC takes too long, maybe you've chosen the wrong modcode from the list. Also, weak signals mean more CPU load for LDPC decoding.

    Next version won't have the list, because it's coded inside the DVB-S2 frame anyway. I'll also implement multithreading for the LDPC decoder, so it will benefit from multiple CPU cores.

    Hi To the whole group, from yesterday I can't receive and I don't understand the Show signal and it's difficult to quickly encode, no video there is another system to understand how to do it thanks

    73 IK1HGI Tony


    Hello to the whole group, since yesterday I can't receive and I don't understand the Show signal and it's difficult to quickly encode, no video, there's another system to understand how to do it thanks ..

    I am 3 nights I can not encode this blessed Sym Rate 2000 no coding !!!!! I had to activate Minitiouner to understand who, maybe until the end IW4APQ my friend Franco, difficult with the DVBS program Gui v 2.12 SWL - markro92 you can get on the new version, the ways to find a fast coding performance to the DVBS GUI program

    73 Tony ik1hgi

    DB8TF HI QUESTION HOW NEVER USE THE FREQUENCY 1106.009 OTHER WAY TO USE LNB THANK YOU

    73 IK1HGI Tony

    Hi Tony,


    i think you ask why i receive the WB on around 1,1GHz.


    The main cause is that i wanted to modify my LNB in a way that i can receive the WB with a custom DVB-S2 receiver.


    I am lucky to own two of the good old Octagon Twin LNBs with the RDA chips and 27MHz crystal.


    So i modified one of the RX-paths of the LNB to external reference injection via the F_connector (1-wire solution)

    and feed it from an 26MHz TCXO which is in the shack. Because the temperature in the shack is mostly constant

    the TCXO and the LNB LO does only minimal drift. (about +/- 50Hz per hour).


    Back to the initial question:


    I removed the 27MHz x-tal from the Octagon (original 9750MHz LO) and with a 26MHz reference i got a

    9388,888 MHz LO frequency.


    The WB downlink is 10491 - 10499(,5?)MHz and with the new LO i can receive it on 1102,111 - 1110,111MHz

    with a custom sat-receiver.


    VY73s DB8TF

    I found the phase noise was poor on my Octagon quad with a 24 MHz reference (normally 25MHz) so I investigated good frequencies. Setting a 9.5 GHz LO with a 24.35897436 MHz reference worked well. The maths is easier too. Now I can use an Octagon SF8008 to receive DATV as the IF is above 950 MHz.


    Mike

    @SWL - markro92:


    can you please check if Terratec dongle will work correctly with DVB demodulator? I have tried to check, but have a problem. Utility defines dongle, 'open device' button works correctly, but 'BB Gain' button do nothing - dongle works with MAX gain level and no possibility to decrease gain level. It seems that dongles works incorrectly with utility.

    Quote from G0MJW

    I found the phase noise was poor on my Octagon quad with a 24 MHz reference (normally 25MHz) so I investigated good frequencies. Setting a 9.5 GHz LO with a 24.35897436 MHz reference worked well. The maths is easier too. Now I can use an Octagon SF8008 to receive DATV as the IF is above 950 MHz.


    Mike

    G0MJW

    hi Mike,

    can you tell me how you measured the phase noise of the LNB?

    not to "pollute" this thread you might open a new one or write to me directly.


    thanks!!!

    Claudio I was asked that question before and I had thought I had made it clear that I do not measure the phase noise directly. I measure it by its effect. I am sorry but it is all I can manage at the moment without access to an RF test lab. There is a well known relationship between the phase noise and the error rate but there is also white noise present. To a very rough, no warranty given or implied, usual disclaimers apply, approximation you can assume the effect of phase noise on a QPSK demodulator is just like that of amplitude noise. This is so rough and wrong that many RF engineers will be at this point shouting "YOU CAN'T DO THAT". Which to be fair is true but the approximation close enough for telling if something is adequate, bad or really bad. The constellation is also useful as if the points look randomly distributed around the ideal phase noise probably is not the problem but if they are in arcs around the points it probably is.


         


    However, you can measure Phase noise directly by analysing the baseband spectrum of a pure carrier that the LNB has down-converted to IF. The problem is you end up measuring the weakest link, and from the satellite, the signals are just not strong enough to get the dynamic range needed to differentiate between the oscillator phase noise and the white noise (unless the LNB is really bad). Therefore a local very pure reference signal is needed, e.g. a good crystal oscillator multiplied up to 10.5 GHz. Even then, with an IF around 1 GHz an SDR is probably not good enough so this IF would need to be mixed down to baseband with another good oscillator. Then look at the output amplitude and phase with a direct sampling RX like a CloudSDR, SDRIQ etc. Spectravue would be a good tool I think.


    This is complicated and needs careful calibration and attention to detail to make the measurement setup as clean as possible.


    Fortunately, there is an easier way to infer the phase noise degradation, measure it and minimise it. Basically, if the MER does not meet the expectations of the SNR, the difference is probably the phase noise.