The transmission over Qatar Oscar 100 satellite with SDR Console

Avant d'émettre quelques réglages avec SDR Console

SDR Console settings

Step by step

  1. Connect your SDR transceiver to your computer.
  2. Follow the instructions for installing the driver for your equipment
    • In the case of LimeSDR, install the LimeSDR USB driver [ download, or newer, unzip, and in the directory corresponding to your installation_ 32 or 64 bits, OS version then install the FTDI driver – inf file ]
  3. Run SDR Console. At the first launch, the software suggests that you search for your SDR equipment, which must be connected to your computer.
  4. On the Radio Definitions window, click Search to add your equipment that you have connected to the computer. Here I am looking for the LimeSDR key.
  5. The key is then added to my “Radios” configuration. Don’t forget to click on the “Save” button.
  6. I now invite you to follow the SDR Console setup steps already published in my previous article on reception (from Conversion Frequencies subsection, to the bottom of the page, so that reception is implemented, and the frequency stabilized automatically.

  7. Start SDR Console
  8. Set the reception frequency by typing or clicking on the sliders above and below each digit of the reception panel

  9. Adjust the signal levels displayed on the spectrum, using the Low, High and Zoom sliders, buttons that appear at the top right of the spectrum. For my part, once the Low and High levels have been set, only the zoom is useful (On the View tab, Low, High, Zoom subpart, I uncheck Mouse-over buttons, and tick Auto center so that the zoom is always done around the reception channel.


  10. Here are some settings I make to improve the quality of reception :
    1. On the left panel Receive, click AGC = Off, and push the reception gain. This reduces some noise.

    2. Activate the NR1 noise reducer and adjust around 8 dB.
    3. Enable the pseudo stereo function that enhances listening (check Enable and keep the default settings)
  11. Now that we have active reception and frequency adjustment (thanks to the stabilization feature), we will proceed to transmission: display the transmission control panel via the Transmit menu, then the DSP button. The Transmit side panel is present on the right side of the screen. This panel can only be displayed for SDR equipment with the transmit function. For LimeSDR, only the 750 kHz bandwidth offers this possibility.

  12. Now set the shift on transmission (frequency difference between the displayed reception signal and the transmission frequency): This difference is constant and is equal to 8089.5 MHz. (10489.800 – 2400.300). This will allow you to transmit on the correct up frequency to the satellite with a simple click on the signal of a received station and be able to respond to that station.

  13. Set the USB reception mode and click on the transmitted panel on the bottom Sync RX button (this copies the reception mode). By activating the upper Sync RX button, you will always have the same transmit frequency as the selected receive frequency. In use, I prefer not to activate this synchronization and instead use the RX > TX button which copies the transmission frequency on demand. This allows you to follow a signal from a station whose frequency drifts without changing the transmission frequency to the satellite.
    Connect a microphone to your PC, or use the internal microphone of your laptop. The solution of a headset is recommended in order to benefit from the reception quality (pseudo-stereo) and avoid that you send back by through the satellite again the sound incoming the microphone. This effect generates echo and feedback.
    Select the corresponding microphone audio channel on the Transmit panel. Increase the gain by pushing the slider to the right.
  14. Before you even pass in transmission, check at the bottom of the Transmit panel that the audio signal appears in the Spectrum oscilloscope when you speak.

  15. Set your transmission frequency in the satellite band. If you have properly set up the shift as described above, it is normal that the frequency displayed below 10 GHz.

  16. Before switching to SSB transmit, I invite you to check your transmission using the Tune button, which emits a tone. Adjust the power level of your signal with the horizontal Drive slider. You should see your satellite signal when you receive it. Stop the transmission by clicking on the same button.

  17. To switch to SSB transmission now, click on the square TX button. While the TX button is active, you will need to increase the power level of your SDR transmitter by sliding the Drive slider to the right. With full-duplex reception you should get along with the satellite in feedback.


One thought on “The transmission over Qatar Oscar 100 satellite with SDR Console

  1. Bonjour Christian,
    Superbe travail…Bravo et merci de faire partager.
    Je voudrais démarrer sur QO-100 sans aucune expérience satellite (OM).
    J’ai compris que dans votre description de la partie réception, vous utilisiez un dongle RTL mais qu’ensuite lorsque vous décrivez la partie émission, vous utilisez un transceiver Lime SDR pour l’émission et la réception.
    – Je ne comprends pas bien quels sont les éléments de la photo ci-dessus..?
    – a priori le mode de fonctionnement est le full-duplex mais je ne vois pas comment il est possible de connecter simultanément la sortie de la tête 10GHz et l’antenne hélice d’émission via les différents preamplis et amplis mentionnées.
    Merci pour votre aide.

    Hello Christian,
    Great work…Well done and thank you for sharing.
    I would like to start on QO-100 without any satellite experience (OM).
    I understand that in your description of the reception part, you use an RTL dongle but then when you describe the transmission part, you use a Lime SDR transceiver for transmission and reception.
    – I don’t quite understand what the elements of the picture above are…?
    – a priori the operating mode is full-duplex but I don’t see how it is possible to connect simultaneously the output of the 10GHz head and the transmission propeller antenna via the different preamps and amplifiers mentioned.
    Thank you for your help.

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