This document discusses using GNU Radio for space research applications. It describes hardware-defined versus software-defined radios and commercially available SDRs. GNU Radio is introduced as free and open-source software that can be used with an SDR to create signal processing applications through a graphical interface. Examples are given of using GNU Radio for ground-satellite applications like receiving weather satellite images. The document also describes a federated satellite systems approach and a prototype FSS negotiator using GNU Radio. An experimental MONSTER project is outlined that used GNU Radio on a Raspberry Pi to transmit and receive data between high-altitude balloons.

1. GNU RADIO FOR SPACE
RESEARCH
RUSTAM AKHTYAMOV
Research Assistant, Skoltech
rustam.akhtyamov@skolkovotech.ru
23rd October 2015
SkoltechOn Conference,
Skolkovo Institute of Science and Technology, Moscow

2. HARDWARE-DEFINED VS SOFTWARE-
DEFINED RADIOS
Mathematical representation
eAM = (1 + mˑsin(ωmt)) sin(ωct)
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AudioAM
Mixer
Local
oscillator
sinωct
Coherent detector
A
D
DSP
Analog to
Digital
Converter
Digital
Signal
Processor
Ideal SDR receiver

3. COMMERCIALLY AVAILABLE SDRS
(STARTING FROM $10)
HackRF
USRP B210
BladeRF
RTL SDR dongle
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4. • GNU Radio is a software to perform the signal processing;
• It has a GUI to create signal processing applications by drag-
and-drop.
Generate Python code and execute the code
Generate Python code
A port's colour indicates the type of
samples flowing through the port. The
colours also apply to block parameter fields.
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5. GNU RADIO FOR GROUND
SATELLITE APPLICATIONS
• Images from NOAA weather
satellites;
• Nano and pico satellites telemetry;
• Studying the Earth ionosphere.
[Image credit]: http://websterling.com/
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6. FEDERATED SATELLITES
SYSTEMS APPROACH
[Image credit]: Lluch – an FSS architecting framework
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7. FSS NEGOTIATOR PROTOTYPE
(OCTOBER 2015)
Satellite emulator FSS negotiator Destination satellite
[Image credit]: Akhtyamov, Lluch, Golkar – SOFTWARE DEFINED RADIO IMPLEMENTATION OF
A NEGOTIATOR NODE TESTBED FOR FEDERATED SATELLITE SYSTEMS
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8. Receives and
demodulates
the signal,
decodes AX.25
packets
Control script
Stores the data and
starts forwarding,
when it is required
FSS NEGOTIATOR (RECEIVE,
STORE AND FORWARD DATA)
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9. MONSTER PROJECT (APRIL 2015)
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10. MONSTER. EXPERIMENTAL SET-UP
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HAB2
32 km
Ceiling
Altitude
5 element Yagi on Celestron tracking
mount
Ping for status/ Receive broadcasts
HAB1
3kg platforms
6,6 m/s
Ascent Rate
Each HAB broadcasts its telemetry data comprising coordinates, altitude, time, and
relays data from the other HAB upon receiving.
Tracking
Ground
Station (GS)
2 Stratospheric Balloons (HABs)

11. Transmitter script
File Source  Packet Encoder  GMSK Mod  Polyphase Synthesizer  Sink
MONSTER. GNU RADIO FLOW GRAPHS
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Receiver script
Source  Xlating FIR Filter  GMSK Demod  Packet Decoder  File Sink

12. CONCLUSION
• GNU Radio is widely used as an toolkit to create
ground satellite applications. But it also can operate
on embedded systems such as a Raspberry Pi 2, so the
possible list of applications might be significantly
broadened;
• Although GNU Radio is not very friendly for beginners
at present, it is an open-source project, so it constantly
evolves and might be much more convenient in the
future thanks to efforts of thousands of people.
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