Posts by DD4YR

    Hallo 17:28:15UTC GOOD RCV FT8 CQ DD4YR JN57 +5dB

    Jürgen, tnx for info!


    I made this afternoon a lot of tests:


    Finally it was necessary to stabilize the PLL of the up-converter with GPSO to read signals down to -15 dB stable ...


    (btw: 50mW in a 1,2m dish results 10 dB SNR FT8)


    73´s de Robert

    Now we are here again and so happy that our dream comes true..

    Peter, concratulations to your team and you ... I know well, it takes a long time for these projects, and there are only few who have the patience ...

    All the best!


    Robert

    Yes, digi modes seem to work well. Decoded myself yesterday with FT8, QRA64D and JT65A - started a thread on this yesterday. I'm available to try two-way tests now.


    73


    Charlie

    Hi Charlie,

    I´m also ready to start FT-8 two-way tests now...


    10489,670 MHz +-

    I saw a couple of times that stations transmitted so much power that the AGC kicked in. It was immediately visible because the color of the background noise in the waterfall changes. I'm not sure if there already is AGC action before that effect is seen.

    I´ve watched the same and thougt first that something wrong with my reception equipment ... looked horrible on the waterfall ...

    This morning, 06:30 UTC, empty transponder (I´m alone...):

    RX:

    QRG 10.489,798,

    1,5m solid dish, PLL LNB GPSO, LOF 9.200 MHz,

    noise floor NB 17dB above ground noise (-43dB / -60dB)

    SNR 34,6 dB on SDR-play, with


    TX: 5 Watt, 1,2m solid dish, 2,5 turn helix feed


    TX/RX SSB/CW Equipment FT-736R


    Yesterday afternoon with a lot of traffic on transpoder (very strong stations) i think the signal was 6-10 dB weaker. (I did not measure). Is any AGC on the transponder active?


    73´s de Robert

    It would be nice if people can add mixer IC name together with LNB manufacturer name. Something like TFF1015 or RT320M etc because sometime LNB manufacturer name and/or product name doesn't tell much.

    Well,

    the mixer IC is an 3566Q (maybe RA)



    Quarz QRG is 25 MHz.


    This PLL IC is the only one I found which´s PLL works down to 23,589 MHz for LO 9.200 MHz


    Manufacturer not known. (Golden Media ?)


    Bought here: https://www.pollin.de/p/univer…edia-gm-201-0-1-db-571751


    73´s de Robert

    Perfect picture without interruption:

    With a Dreambox I can receive with following parameter:


    Frequenz: 10495

    System: DVB-S2

    Symbol rate: 6500

    Modulation: QPSK

    FEC: 1/2


    Kanal Info:

    Name: A71A

    Provider QARS

    Format: 16:9

    Resolution: 1920x1080


    LNB: GPSO PLL Modified Golden Media, LOF 9200 MHz,

    SNR 7,4 dB (1,5m solid dish)


    73´s de Robert

    DD4YR Robert can you share your solution here?

    Of course. I oriented myself on an article on EngineerZone from Analog Devices. The source code for MATHLAB can be used 1:1. fits.

    The measurement takes place in two steps. First, the forward current power is detected from the reflectometer on the frequency spectrum to be scanned. Then, you have to change the reflectometer, in the second step the reflected power is recorded, subtracted and plotted.

    The only drawback: Yo can not measure in real time, since the measurement runs already takes 2 minutes ...


    Items: https://ez.analog.com/universi…r-vector-network-analyser


    btw: I use the 30 days trial version of MATHLAB .. :-)


    73´s de Robert

    Anyway ...

    Another idea: ADALM-PLUTO has integrated RX and TX, actually the ideal condition to use the device also with suitable software as a VSWR (reflection attenuation) measuring device via a directional coupler.

    Has any of you aoready tried it? Any idea?


    73´s de Robert

    Task solved ..

    I´ve now found a solution using MATHLAB to use ADALM-PLUTO as an SDR reflectometer. The result is amazingly good. Comparisons with purchased SHF filter and R&S measurement results are the same.

    Here a plot of my 3-band helix feed, the 13cm part:



    73´s de Robert

    Anyway ...

    Another idea: ADALM-PLUTO has integrated RX and TX, actually the ideal condition to use the device also with suitable software as a VSWR (reflection attenuation) measuring device via a directional coupler.

    Has any of you aoready tried it? Any idea?


    73´s de Robert

    Latency of Adalm-Pluto...


    I think a not negligible problem is the digital processing times plus the latency over the satellite. Since come equal 1500 mS together (RX 600mS - Sat Latency 250mS - TX 600mS). Maybe a problem for FT8?