QO-100 Ground Station

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1 Scope

My first QSO via QO-100 took place on 01.03.2019 with DF6NM at the portable station of my friend Severin DL9SW. Since then I wanted to acquire the capabilities to transmit to the satellite myself and receive it's signals.

In summer 2022 I met a trainee in my company who wanted to learn about satellite communication, and given that I am working in a satellite project for Airbus, it was apparent that there was a chance to build it.

In fact such a project gives me quite a number of topics that I can teach to our trainees:

  • Requirements Engineering
  • Mechanical Planning
  • Electrical Planning
  • Electrical Engineering fundamentals
  • RF Engineering fundamentals
  • Electrical Safety
  • Specifics of Satellite Radio Communications
  • Electrical Measuring
  • Software Defined Radio
  • Microcontroller Programming
  • Embedded Systems / Embedded Linux (Raspberry Pi)
  • Linux System Programming
  • Networking
  • GUI Design / Browser Engineering
  • Quality Assurance (IVV)
  • Practical Radio Operations

So this project is rather fruitful.

2 Components

Antenna Unit

Main Unit

User Unit

  • MPC-4LAN-N3700 MiniPC
  • Kingston KC600 256G SSD SATA3 mSATA - SKC600MS/256G
  • Crucial CT102464BF186D 8GB Speicher (DDR3, 1866 MT/s, PC3-14900, SODIMM, 204-Pin)
  • Rode USB-NT Microphone
  • USB speakers
  • MikroTik RBD52G-5HACD2HND-TC Wireless Access Points für hAP ac2
  • USB Port Extension
  • USB Keyboard
  • USB Mouse
  • Screen

3 Circuit Description

Generally I wanted to have a QO-100 transceiver that can be set up at a distant place with an internet connection so that I can access it through my VPN. It should be capable to work full duplex and the user interface should be just a Web GUI, so that using a simple browser would allow me to operate it from almost anywhere.

The configuration that was most likely to fulfill all these requirements was the RaspberryPi 4B based RemoreSDR software from André Buhart F1ATB. André also supports the usage of two HackRFs for full duplex and explicitly describes such a setup on his website: https://f1atb.fr/index.php/2022/05/21/remote-sdr-v5-raspberry-4b-or-orange-pi-image-installation/

The antenna unit is designed to downconvert the RX signals immediately to a reasonable frequency (10 GHz -> 430 MHz). The Kuhne LNC is actually for operation with analog 70cm devices, but it serves perfectly fine with a HackRF also. In order to produce the necessary voltages, a bank of DC buck converters was used. The needed voltage will then be chosen with a 4 module relay bank. The control of the relay bank, but also other parts of the entire installation is done by an Arduino which is hooked up serially to the RaspberryPi. This Arduino gives me full remote monitoring and station management capabilities.

Most interesting is the Kuhne Bias Tee, because one of the most challenging problems is frequency stability. My installation will e mounted outside with sunshine heating up all the arrangement. So frequency drift will be a major issue. The Kuhne Bias Tee will allow to insert a 10 MHz reference signal and send it up to the antenna. Off course I have more 10 MHz consumers, which are the HackRFs. So consequently I needed a distribution amplifier, which I found from CircuitValley, which has four ports. The generation of the 10 MHz signal will be done by a Weber GPSDXO disciplined oscillator.

3.1 Control Circuit

Here is my controller program: 

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3.2 Software

The software I am using comes from André Buhart. It is well usable and does it's job. Note that André does not put great attention on station usage security, so I recommend to use it only in a trusted environment, i.e. within your VPN or in your home LAN. There however it is a really fabulous piece of operation software.

4 Test Management

5 Images

  • 2022-10-01-qo100-1.jpg 2022-10-01-qo100-2.jpg
  • 2022-10-01-qo100-3.jpg 2022-10-01-qo100-4.jpg
  • 2022-10-01-qo100-5.jpg 2022-10-01-qo100-6.jpg
  • 2022-10-01-qo100-7.jpg 2022-10-01-qo100-8.jpg
  • 2022-10-01-qo100-9.jpg 2022-10-01-qo100-10.jpg
  • 2022-10-01-qo100-11.jpg 2022-10-01-qo100-12.jpg
  • 2022-10-01-qo100-13.jpg 2022-10-01-qo100-14.jpg
  • 2022-10-01-qo100-15.jpg 2022-10-01-qo100-16.jpg
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