ADS-B in Space: Decoder Implementation and First ...

ADS-B in Space: Decoder Implementation and First Results from the GATOSS Mission Bjarke Gosvig Knudsen, Morten Jensen, Alex Birklykke, Peter Koch Department of Electronic Systems, Aalborg University, Denmark Johan Christiansen, Karl Laursen, Lars Alminde Gomspace ApS, Aalborg, Denmark Yannick Le Moullec T.J. Seebeck Department of Electronics, Tallinn University of Technology, Estonia

About the Project GATOSS  Global Air Traffic Awareness and Optimization through Spaceborne Surveillance

Partners  Gomspace ApS, Aalborg, Denmark  Sub-systems and components for miniaturized satelittes  Aalborg University (AAU), Denmark  Department of Electronic Systems  Tallinn University of Technology (Yannick Le Moullec, former employee at AAU)  T.J. Seebeck Deparment of Electronics  Partly funded by The Danish National Advanced Technology Foundation

What is ADS-B?

Traditional radars  Limited range  Interrogation-protocol based  Requires large safety areas around each aircraft

GPS data

ADS-B GPS data

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Automatic Dependent Surveillance-Broadcast

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Aircraft get data from GPS satellites, calculates speed, heading, etc. Aircraft broadcast (ADS-B out) data Data can be received by other aircraft (ADS-B in) and Air Traffic Control (via ground stations)

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Improved situational awareness, pilots have access to  Information about traffic as well as clear and detailed weather information Reduced safety areas, increased efficiency, fuel savings Limitation  Still need ground stations to relay data to ATC  Does not work over oceans and areas not equipped with ground stations

Project Overview

Geo-stationary orbit Communication satellite

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Collect ADS-B signals from nano-satellites  Low Earth Orbit (+/- 600 km)

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Off-line scenario  Relay data from nano-satellite to base-stations  3-6 nano-satellites

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(Near) real-time scenario  Relay data through geo-stationary satellite  40-70 nano-satellites

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GATOSS mission: demonstration with 1 nano-satellite

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Challenges  Need for high sensitivity (strong signal attenuation)  Low-cost, low-power implementation

GEO Real-time data relay

GEO Real-time data relay

Low Earth orbit Nano-Satellite

off-line data ADS-B signal

10km ADS-B Out Equipped Aircraft

Contributions  Link budget  ADS-B SDR receiver design and FPGA implemention  GATOSS nano-satellite has been constructed and launched

Link Budget

Challenge: need for a highly sensitive receiver

Architecture Payload Board

RF Front-end Antenna

FPGA

MCU

I2C/CSP Interface

Implementation

ADS-B payload prototype

Tests on Ground

SNR = 18 dB

SNR = 3.5 dB

Launch

 21 November 2013

 'DubaiSat-2 cluster‘ mission  31 satellites  Dnepr rocket  Yasny, Russia

Photo: EIAST

Transmission from the satellite

 437.250 MHz  Analog FM modulation  4800 baud MSK modulation

Space-based results

Red: aircraft locations detected and reported by GATOSS (26 Nov 2013 to 22 Jan 2014) Green: great circle routes (Openflights database Jan 2014)

Zoom over the Sahara Desert

Zoom over Europe’s west coast, North America’s East Coast and transatlantic routes

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