Posts by OE3GBB

    On the terminal connection I get contiuously ....aUaUaU.... with some background sound on the speaker. It is very hard to tune the RX to the correct position. It seems that the transmitted audio is repeated somehow.

    Hi George,

    I tried this version with same settings, but had problems to decode the audio. I only managed to get a decoding for short time and with breaks. Audio quality doesn't seem to be improved.

    73 Gerhard

    Hi George,

    thank you for the last change of teh script and the infos over email.

    I could make it running now and could decode my own transmittion over the satellite.

    Your application is having a very good audio quality. I am really surprized.

    congatulations!

    73 Gerhard

    Hi George,

    great work. I have copied the file to the gnuradio directory and started the .py file.

    Unfortunatly I got following errors:

    ...............

    gerhard@GNURadio:~/gnuradio$ python qpskdv.py

    max_amp: 80 m_pitch: 320

    p_min: 20 p_max: 160

    Wo_min: 0,039270 Wo_max: 0,314159

    nw: 279 tw: 40

    max_amp: 80 m_pitch: 320

    p_min: 20 p_max: 160

    Wo_min: 0,039270 Wo_max: 0,314159

    nw: 279 tw: 40

    max_amp: 80 m_pitch: 320

    p_min: 20 p_max: 160

    Wo_min: 0,039270 Wo_max: 0,314159

    nw: 279 tw: 40

    max_amp: 80 m_pitch: 320

    p_min: 20 p_max: 160

    Wo_min: 0,039270 Wo_max: 0,314159

    nw: 279 tw: 40

    Traceback (most recent call last):

    File "qpskdv.py", line 786, in <module>

    main()

    File "qpskdv.py", line 774, in main

    tb = top_block_cls(decimation=options.decimation, ear=options.ear, ipaddress=options.ipaddress, mic=options.mic, rxfreq=options.rxfreq, tx_buffer_size=options.tx_buffer_size, txfreq=options.txfreq)

    File "qpskdv.py", line 392, in __init__

    self.pluto_source_0 = iio.pluto_source(ipaddress, int(rxfreq*1000), int(samp_rate), int(1000000), 0x8000, True, True, True, "manual", rxgain, '', True)

    File "/usr/lib/python2.7/dist-packages/gnuradio/iio/iio_pluto_source_swig.py", line 126, in make

    return _iio_pluto_source_swig.pluto_source_make(*args, **kwargs)

    RuntimeError: Unable to create context

    gerhard@GNURadio:~/gnuradio$

    .................

    Maybe I am missing some installation?

    I have changed the TX frequency to 2400135. Could that be the reason?


    If you want to discuss this offline, please send me your reply to gerhard@oe3gbb.eu.


    73 Gerhard

    Hi,

    just was my not knowing. Screen is complete and block menue also. I just did not remember that I have to click on the black arrows and not on the block groupe name. So I habe Pluto sink and souce and all the others ready.
    Did some trials with gnuradio about 10 years ago with minor success.

    73 Gerhard

    Hi George,

    tnx for the infos. All OK now, installed everything without errors and Gnuradio-Companion is running. Could start a filter example. But cannot open the menue on the right side. There are no devices?

    73 de Gerhard

    Hi George,

    I made a new install of Ubuntu 18.04 and GnuRadio 3.7.

    Then I wanted to install the analog gr-iio, but in line 3 I got errors and line 4 did not start . There must be a syntax error. I am no Linux guy to solve this. I am quite happy if I can install some software without problems following a cook book.

    Any ideas?

    73 de Gerhard

    Hi George,

    I am using Ubuntu 20.04 and Gnuradio 3.8.1 on an i3-5xxx machine. Pluto is GPSDO stabilized and can run duplex over QO-100. I am using the GPIO - relay board for PTT in SDR-Console. Pluto is 192.168.1.7.

    Do you think that equipment will be sufficient?

    73 Gerhard

    Hi George, that is great news. What do I need to test? I allready do have a Ubuntu computer and a Pluto via ethernet.

    73 de Gerhard OE3GBB

    Hi Poll,

    I do have the same board and it is also broken now. I have used it with PlutoDVB FW 0303 and I think it was OK for a while. Now I cannot access the http-server of the box, nor get a telnet connection. I also lost the HDMI screen in OBS.
    - I can hook up a TTL RS232/USB, but how to proceed from there?

    - What is the patch for? Is it necessary for working with 0303 FW and how is it done savely?

    73 de Gerhard OE3GBB

    Hi All,
    According to Austrian regulations all digital modes are allowed, if they do not exceed the bandwith regulations for the frequency band. This includes also experimental modes. But it is necessary to use an open documented digital mode. This can be achieved by using (1) an allready open documented mode, or (2) an experimetal mode. In case (2) it is necessary to show the callsign and mode at the beginning of the transmission (I am using waterfall picture) and give necessary infomation and/or code of this mode at least on a personal internet site.

    73 de Gerhard OE3GBB

    Hi all,

    Many thanks for all the contributions.


    Here are the results from my investigations:


    Yes, it is the 5th harmonic problem. I could tune my LNB to that frequency on 12.038 MHz using SDR-Console and could see some TV transponder signals at -115 dBm. But when I transmit at lower power I get the 5th harmonic of my transmission at -80 dBm. When I increase the power I get -45 dBm. So it seems that the activation of the doherty path of the amplifier is making this problem.
    I inserted now a 200W circulator and the situation improved a little bit. I can transmit now 333 kS at beacon level without increasing the noise level.
    I am using bandpass filters for 10W between driver and final amplifier, built for Wifi on 2410 MHz, 27 MHz bandwith, but 10W CW only.
    High power low loss low pass filters could be built according this: https://www.changpuak.ch/elect…mpedance_Lowpass_Coax.php. But I don't have the ability for that kind of high precession work.
    Alternativly those could be built from low loss PCBs with increased copper layer thickness.

    I also do have a WLAN duplexer, but only rated for 20W and I don't want to risc this eather.
    So next will work on optimizing the doherty amplifier to reduce the 5th harmonic.


    73 de Gerhard OE3GBB

    Hi Mike,
    that is a very good point. I do not have a SPA for this frequencies, but I will try to tune my LNB to 12025 and see what is there.
    If the 5th harmonic is the problem: This is the first PA I am using without a circulator. So, I also can try ma 200W circulator for 2,4 GHz and maybe this device is acting also as a low pass filter ? How to build a LPF for 200W on 2,4 GHz with minimum losses? I also will try to change the amplifier from Doherty to push-pull A-amp as a last try as maybe the problems arise when the C-part of the amp is activated.
    Will keep you informed.

    73 Gerhard

    Hello, I am using a 1,2m offset dish and a POTY feed. Never had that problem before with different amplifers from low power up to 70W. But now I have built an new amplifier using a Doherty transistor pallet module. I am getting increasing noise on the RX (MiniTioune Scan & Tune), if I increase the transmitting power. I don't have this with the diver stage alone, which is also good for 20W DATV. I do have a very sharp band filter (-70 dB) just before the final amplifier. And I cannot see any spurious signal up to 2,9 GHz on the HP spectrum analyser. Shoulders at 75 W output are at 30 dBc. The signal on the WebRX is very clean and I can produce a 16APSK signal at 15 dB without shoulders. I don't have an increase of noise on my nearby 85 cm dish, while I am transmitting with the bigger dish.
    So, what can it be? I don't have oscillations, I don't have a spurious emission on 2,6 GHz. The only difference to the other amplifiers is, that this one is a Doherty type. The operating point of the transistors are correct according to the data sheet and changed only a little bit to increased linearity, but without any change to this noise problem.

    Has anyone had this problem before or has some idea what I could check?

    73 de Gerhard OE3GBB