Posts by dj0abr

    triggered by the current discussion about the max. uplink power, I have extended this Web SDR with a beacon level monitor.

    It measures the maximum level of the beacons and displays its value as a red line.

    The measurement is taken over >1min, so the maximum value is still valid if the beacon sends CW.

    Its a nice tool to check if the own (and others) transmission is in the limits of the QO-100 rules. Additionally it can be used to measure the bandwidth of a signal in the lower HiRes waterfall.

    this program is now combined with the WB Transponder monitor into one software, selectable by the build file.

    The github link is:

    73 de Kurt

    I think we should know a bit more about the technical background.
    There is no way to control uplinks from half of the world and I hope that there are more things which can be done to stop these alarms, i.e. reduce 10 GHz output power or anything else.

    But, G8UGD, you are right, maybe its better not to talk about it.

    For a better understanding we should know how the NB transponder is working.

    The issue came up yesterday when a strong carrier was sent to QO-100 at 5:30 in the morning.

    At this time usually nobody is active, the transponder shows the beacons only.

    How can a single carrier at this time of a day ring the bells in es'hail2 office ?

    Does the NB transponder use any kind of AGC ?

    Is the TX power of the 10 GHz transmitter strong enough to cause any harm on es'hail-2 ?

    We know only very little about the functions of NB and WB transponders.

    thanks to everybody for testing the monitor.

    It may be a bit slow because my internet upload speed is at its limits if more than 20 users are using the site,
    but thats good for stability testing :-)

    This evening I will try it on a new RPI-4. I don't expect that the RPI is fast enough, but I'll give it a try.


    usually the webmonitor is used to see the activity on the QO-100 wideband transponder.

    I needed to see a similar picture, but from my own dish and LNB to compare it with the batc spectrum. And I want to
    stream it into the Ethernet or Internet like batc is doing.

    Using the hardware SDRplay RSPx I have written a web monitor including spectrum and waterfall.
    The software runs under Linux. Since the capture rate is 10MS/s a PC is needed (but I had also some success to run it on an Odroid-N2 SBC).

    Currently I have it running for testing on a desktop PC which is connected to an RSP1A SDR and a 120cm dish with a Megaset LNB.

    It can be view here:


    (for easy use, activate to "Autom:" checkbox and set the "average" slider according your preferences).

    After some testing and debugging I will publish it via Github during the next week for general use.

    vy 73
    Kurt, DJ0ABR

    ok thanks, that makes sense. So if I choose 1/4 than only one quarter is used for video. This is why my TX buffer is filled up to 99%.

    It also explains why 9/10 gives the best results in my local transmission over only 5m distance,

    Friday is my free day, so time to hobby! As guinea pig #2 built the 'Radioclub 't Gooi' (PI4RCG) MMIC amplifier however, deviated a little from the original design (didn't had all the parts, so the junkbox is always my best friend ; -) and used two TQP3M9009's as driver MMIC's (original design uses two SBB3089z's). My MMICs have more gain and hopefully all will be stable! Amp has to be tested of course...

    that looks really good ! Please think of a PTT input to switch off the quiescent current during RX.

    thank you for answering my questions,

    Heiner, a test with 2000 kS/s worked fine too,

    For 333 kS/s:
    G0MJW : that did the trick. I reduced the input resolution to 640x480 and the picture was fine.

    An additional improvement was to change the FEC to 9/10.
    Can anybody explain what this FEC setting is doing ?

    With 1/2 I still have some blocks, with 9/10 the picture is clean.

    With some other FEC settings (i.e. 1/4) the TXbuffer fills up to 99%.

    I am trying to get a DVBS2 TX running with Pluto.
    In general it works, but the video quality is very bad.

    PC: Win7, Intel i7 16-cores, 16GB ram

    Pluto: all hacks installed, second core activated
    Pluto connected via USB or ETH (makes no difference)

    Software: DATV express, 333 S/s

    Cam: 1920x1080p webcam

    Receiver: SF8008

    RX signal strength: 99%

    When I receive videos (333 S/s) via QO100 from other people using pluto, all looks fine, nice quality.

    When I directly (not via QO100) receive my own signal, generated by pluto, there are strong artifacts and blocks. These blocks are "pumping" every second, the picture gets very bad and then improves a bit during the next second. When objects in the video are moving, I see only blocks and extreme artifacts like the tail of a comet.

    Please can anyone post the settings of the datv-express menus, or has another idea what I could try to improve quality ?

    73, Kurt, DJ0ABR