Offline Analysis of BeiDou MEO-3 Signal Quality

C-Y. He, J. Guo, X. Lu, X. Wang

Abstract:	With the successful launch of the first MEO satellite named BEIDOU-M1, by a Long March-3A carrier rocket at the Xichang Satellite Launch Center on 14 April 2007, China is set to become the latest entrant into global navigation satellite systems (GNSSs). Two years later, the first GEO satellite named BEIDOU-G2 was launched on Apr.15 2009. Till now, 14 navigation satellites have been launched successfully. Unlike previous satellites, they have similar frequencies and signal structure to other GNSS, making the prospect of interoperation a tantalizing one. To achieve precise navigation, positioning, velocity measurement and timing, navigation signal is of vital importance. This is mainly because the PVT results may be affected due to some unpredictable anomalies in satellite life cycle, such as emission power decrease, satellite’s roll attitude, antenna pointing anomaly, etc. Through real time monitoring and in-depth analysis of GNSS SIS (Signal In Space) quality, we can detect abnormalities at the first time, and then evaluate the causes of signal distortion, therefore to better assess the performance and working state of satellite. The use of a high gain antenna can greatly aids the effort to assess BEIDOU signal quality. For data collection, we mainly use the NTSC GNSS Signal Quality Monitor Station. The station has a 7.3-meter steerable parabolic dish antenna with an L-band feed. The system can not only monitor Beidou signals, but also can observe other GNSS signal like GPS and Galileo (GIOVE-B) signals. In this paper, signal analysis using the sampled Beidou MEO-3 signal includes PSD (power spectral density), scatter plots, eye-diagram, chip shape, correlation function, S curve and occupied bandwidth, etc. Those results have been compared between different dates. In order to better assess signal quality, a novel and comprehensive method is proposed. We use several different methods to assess the modulation quality and chip characteristics of the collected signals. Those methods we used to assess signal quality will be introduced in detail in this paper. Measurement and analysis results show that, there are no relevant signal changes during several measurements in different days, and no new emissions have been detected, there is not much distortion in the signal quality. To sum up, monitoring and assessing GNSS signal quality is benefit to the development of GNSSs, and will further promote researches on compatibility and interoperability. GNSS signal quality monitoring and assessing is an international and long-term work. It’s necessary to implement international cooperation with more organizations and countries.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2739 - 2748
Cite this article:	He, C-Y., Guo, J., Lu, X., Wang, X., "Offline Analysis of BeiDou MEO-3 Signal Quality," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 2739-2748.
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