The transmission over Qatar Oscar 100 satellite with SDR Console

Mesurer sa chaîne d'émission

Measuring devices

The milli-wattmeters

To dispel doubts about power levels, it is useful to equip yourself with a milliwattmeter. It will allow you to check your emissions levels at different points in your emission chain and ensure that you do not apply excessive levels to downstream equipment.

There are also products available on the Chinese market:

    • ImmersionRC RF meter

      An ImmersionRC wattmeter designed for power measurements of transmitters for models (aircraft, drones) (Link to Aliexpress)

      • Power level: -20dBm up to + 30dBm with 30 dBm attenuator included. Runs on rechargeable battery
      • Not personally tested
    • A “powermeter”, milliwattmeter based on RF detector AD8318 from -55 to -5 dBm (Link to Aliexpress)

1-8000 Mhz milliwattmeter with -55 to-5 dBm with OLED display and keys

Spectrum analyzer

A spectrum analyzer can also be used to measure levels and check the spectral “purity” of your transmitters. Always be careful that you do not apply a higher level that is acceptable to your analyzer. An analyser with tracking (generator), combined with a directional coupler, will also allow you to determine the return loss of an antenna. For amateurs, I suggest you watch this video explaining the measurement method. Resources (in french) are also available on the REF 68 website.

LTDZ 35-4400M spectrum analyzer

I suggest you to discover this ultra portable spectrum analyzer LTDZ 35-4400M connectable to a Windows™ computer , and to use with its software (To download WinNWT).. This is the Link to Bangood.

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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