Posts by DD1US

  • MY QO100 SETUP

    Hi George,

    building a braodband DC-block by putting 2 capacitor of 1uF and 1nF is dangerous. It depends on the capacitors but I am afraid the 1uF will have a series resonance fequency which is quite low. Above that series resonance frequency that 1uF actually behaves like an inductor and together with the 1nF capacitor yu have a parallel resonance circuit with a high impedance around that parallel resonance frequency. Did you measure S21 of your DC-block in a wide frequency range ?

    Kind regards

    Matthias

    http://www.dd1us.de

  • recommendations for non-standard modes (station identification)

    Kristoff,


    sounds all good to me. I think we are in synch.


    By the way you are welcome to join in the future development of the AMSAT-DL Highspeed Modem. There are many things which could be added to it andI think it would be a good idea to have a common user interface for different modes / applications. Maybe you can have a look and we can talk offline involving Kurt DJ0ABR who is the developer.


    Kind regards


    Matthias


    http://www.dd1us.de

  • recommendations for non-standard modes (station identification)

    Hi Kristoff,


    let me chime in.


    As Peter explained encrypted messages are not allowed in ham radio.


    We can use digital modulation with coding schemes which are published for instance in Github.


    The AMSAT-DL HighSpeed Multimedia Modem for instance is available on github.


    It has been published in the AMSAT-DL journal and also the German DARC journal. In addition the documentation is available online.


    Before a digital transmission starts the mode which is being used is anounced in analog voice. Thus people know what to choose to decode the transmission. In the digital transmission the callsign is encoded. Thus you can see it in the GUI who is transmitting.


    When using hsmodem you can choose whether the analog announcement is done before every transmission or every second .. every third ...


    There are no certificates used. Thus you are right people can make transmission using a fake callsign just like in other modes.


    I hope this answers your question.


    Kind regards


    Matthias


    http://www.dd1us.de

  • Highspeed Multimedia Modem for QO-100

    Hi Elmar,


    as far as I understand the documentation you can use the trail version which supports up to 256 cables.

    It is equivalent to the full version but there is a femal voice taking after 30 minutes. This should be fine

    for testing.


    I have the full (licensed) version.


    Kind regards


    Matthias


    http://www.dd1us.de

  • Highspeed Multimedia Modem for QO-100

    Hi Elmar,


    I heard from several OMs having trouble with VB-cable and hsmodem, even though VB-cable worked with other applications.


    If you have a chance, could you please try VAC ? Pleae make sure that VB-cable and VAC are not running at the same time.


    I am using only VAC and that works fine.


    Kind regards


    Matthias


    http://www.dd1us.de

  • Highspeed Multimedia Modem for QO-100

    Hi Flo,


    sure I remember your programming skills and therefore I asked you seriously to contribute to the project.


    As I wrote Kurt is presently devoting all his time in this project.


    There have been problems getting the Highspeed Modem running on all platforms and Kurt is adressing this first.


    Once this is stable (v0.72 is in my opinion a good candidate) additional features might be added.


    Kind regards


    Matthias


    http://www.dd1us.de

  • Highspeed Multimedia Modem for QO-100

    Hi Flo,


    please be patient. Kurt has worked a lot in the last week to fix some soundcard related issues.


    Do do not believe how many hours he has spent in this development.


    But as he is making the sourcecode free available maybe you want to join and do some work yourself on the missing features you are asking for ?


    Kind regards


    Matthias


    http://www.dd1us.de

  • AMSAT-DL Online Satellite Symposium on September 26th, 2020

    Hello,


    here are some additional details on the AMSAT-DL Online Symposium 2020 and Virtual QO-100 Usermeeting


    The AMSAT-DL Symposium will start at 09:00 CEST (0700z) and will be followed by the QO-100 virtual user meeting starting at at 17:20 CEST (1520z) on the narrow band transponder.


    You are invited to ask questions during the Symposium and announce your participation for the Usermeeting via WB tpx chat on [1] (please set you nick Name with "/nick N0CALL" to your callsign) or via the YouTube chat on [2]. Please note that you need a registered Youtube account to be able to enter your questions in the chat window of Youtube. This is not related to our streaming but a general requirement.


    We will stream the Symposium on the wideband transponder of QO-100 with the following parameters:

    Callsign DK0SB

    Frequency 10494 MHz

    Symbolrate 2Msps

    Modulation QPSK


    During the Symposium we will address the questions after each presentation to the presenters (we may not be able to ask all questions as we are limited in time).


    With respect to the Usermeeting we will collect all the pre-registrations and call you one by one on the narrowband transponder at 10489.830 MHz using the callsign DK0SB. As soon as the list is processed, we will go split and listen approx. 10 up for any other users.


    [1]: https://eshail.batc.org.uk/wb/chat


    [2]: https://www.youtube.com/watch?v=QNRahMn2dYE


    Kind regards


    Matthias


    http://www.dd1us.de

  • SG-Labs 20 W PA V.3

    Hello Geri,


    reading the thread again I guess you were referring to the Pluto and not the Lime.


    As far as I know the feature I described above is only available for the Lime.


    Sigi has described in the SDR-Betatester-Group a way how to do it with the Plut. More complicated but also possible.


    Kind regards


    Matthias


    http://www.dd1us.de

  • SG-Labs 20 W PA V.3

    Hello Geri,


    if I understand your problem correct there is already a solution in SDR-Console:


    go to the "LIME-SDR setting" and then to "Drive"


    Here you can activate a "custom drive range" with a checkmark.


    You can then set the minimum and maximum drive levels.


    Here is the explanation from the help window in SDR-Console:


    Drive

    The default drive range of the LimeSDR is 73dB which is far more than required, also this makes it difficult to select the desired value. A custom range makes adjustments much easier. The exact values you select will depend on the amplifiers used between the LimeSDR and your antenna.


    Maximum

    When running the LimeSDR at maximum output the signal may suffer from Intermodulation distortion (IMD), so set the maximum value to -10dB or -15dB.


    Minimum

    Set the minimum value somewhere between 20dB and 30dB lower than the maximum.


    I have set here my Lime-USB to min -40dB and max -10dB. For me a range of 30dB for setting the TX output power is fully sufficient and with the max of -10dB I cannot overdrive my PA and the output signal from the Lime is nice and clean.


    Kind regards


    Matthias


    http://www.dd1us.de

  • AMSAT-DL QO-100 DownConverter V3d: how to connect OLED

    Hallo Joachim,


    ja, man sollte auch TCXOs stets vor Luftzug schützen. Ich habe meine Transverterkomponenten auch stets separat in einem Weissblechgehäuse eingebaut. Etwas Schaumstoff auf / um den TCXO positioniert reicht aber auch schon aus, um ihn thermisch zu isolieren.


    Es gibt auch ein schönes 3D gedrucktes Gehäuse in welches man das OLED einbauen kann und ausserhalb des Transvertergehäuses betreiben kann. Im Amsat-DL Journal ist auch davon ein Bild zu sehen und die Info wer diese Gehäuse drucken kann.


    Viele Grüße


    Matthias


    http://www.dd1us.de