More Compass Points: Tracking China’s MEO Satellite on a Hardware Receiver

Launch of a Compass Satellite

On April 14 China launched its first medium-Earth-orbit (MEO) satellite code-named Compass-M1, the first in a planned constellation with global coverage based on the same principles as GPS and Galileo. In order to investigate the space vehicle’s characteristics and data structure, researchers modified a GPS/Galileo hardware receiver so as to track the Compass MEO satellite. This article tells how they did it and presents the first results of their efforts.

Wim De Wilde, Frank Boon, J-M Sleewaegen, and Frank Wilms
(Septentrio N.V.)

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In 2000 China deployed the Beidou-1 navigation system. Originally this S-band system provided ranging information via geostationary satellites that operate as transponders. This system design required bulky two-way radios, had a limited capacity, and coverage was restricted to East Asia.

Currently, China is developing the successor to this system, called Beidou-2 or Compass. The Compass Navigation Satellite System (CNSS) will consist of 30 medium-Earth-orbit (MEO) satellites broadcasting code division multiple access (CDMA) signals in the L-band. Unlike the relatively large user equipment of Beidou-1, Compass will support global navigation by means of small handheld receivers.

This explains the burst of research activity after launch of the first Compass satellite (Compass-M1) in April this year, particularly because China didn’t disclose any details about its operation. In an article published in the May/June issue of Inside GNSS, researchers at CNES, the French space agency, presented dish-antenna measurements of the Compass-M1 signal and unveiled the main code properties. Subsequently, a Stanford University (SU) team undertook complementary measurements and worked out the spreading code parameters.

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Manufacturers

The GeNeRx1 GPS/Galileo receiver used to track the Compass-M1 signals is manufactured by Septentrio N.V., Leuven, Belgium. The choke ring antenna is from Orban Microwave Products (OMP), Leuven, Belgium.

Author Profiles

Wim De Wilde received his master’s degree in electrical engineering from the University of Ghent. Upon graduation he joined the DSL research team of Alcatel Bell. Since 2002 he has been an R&D engineer at Septentrio Satellite Navigation. His areas of interest are analog and digital signal processing and system design.

Frank Boon holds a Ms.Sc. in aerospace engineering from the Delft University of Technology. He is responsible for the design and implementation of positioning algorithms in the firmware of Septentrio’s GNSS receivers. His research interests include error models of GNSS measurements and optimization of positioning algorithms for high dynamic applications.

Jean-Marie Sleewaegen is currently responsible for GNSS signal processing, data analysis, and technology development at Septentrio Satellite Navigation. He received his M.Sc. and Ph.D. in electrical engineering from the University of Brussels in Belgium.

Frank Wilms has a diploma in mechanical engineering, with specialization in spaceflight technology, from the Technical University of Braunschweig. At the university’s Institute of Flight Guidance and Control he worked on real-time data-acquisition systems and integrated navigation systems based on GNSS. In 1999 he was with the Navigation Section of Dornier Satellitensysteme/DaimlerChrysler Aerospace and involved in system architecture tasks within the ESA GNSS-2 Comparative System Studies. In 2000 he joined Septentrio Satellite Navigation in Leuven (Belgium) where he was responsible for GNSS receiver interface design as well as application project management. Since 2003 he has served as manager of Septentrio’s Galileo projects with ESA, CDE1 Test User Segment (CDE1 TUS) and GSTB-V2 Experimental Test Receiver (GETR). Wilms is also involved in Galileo and security-related business development.