GPS L5 "Light's on!" - A First Comprehensive Signal Verification and Performance Analysis

S. Erker, S. Thölert, J. Furthner, M. Meurer, M. Häusler

Abstract:	The constant development in the field of global satellite navigation systems opened the door for a new type of safety critical applications. These applications that are mostly related to aviation generate stringent requirements on the used navigation system. To meet these challenging requirements which include precision of the positioning solutions as well as robustness of the service new technologies have to be implemented in developing and modernized satellite navigation systems. Only the use of new designed signals located on multiple frequencies with the combination of advanced receiver architecture and algorithms will allow achieving these demands. In early spring this year a next important step in GPS modernization will take place. With GPS IIR-20(M) a new satellite will be added to the actual constellation which carries an L5 demo payload. This satellite is intended to transmit the first GPS L5 signals from a Medium Earth Orbit (MEO) in space shortly after its launch. The L5 payload, which has been developed by Lockheed Martin helps to preserve the L5 frequency for the following new satellite generations Blocks IIF and Block III. The paper gives a brief overview of DLRs GNSS verification facility and the previous work which was necessary for these measurements. This includes a detailed description of the measurement setup and the performed calibrations on all components. Afterwards a detailed analysis of the transmitted L5 signal is presented. Possible signal imperfections like spectral asymmetries or distortions caused by nonlinear effects are discussed and evaluated using signal representations like spectra, constellation diagrams, sample analysis and correlation functions. The antenna pattern of the satellite in the L5 frequency band is derived next to the radiated power over the elevation using the absolute calibrated measurements. Finally the influence of different interference for the measurements in the L5 band is discussed briefly. Summarizing the paper gives a first insight into the quality and potential of the new GPS L5 signal in space as well as into the navigation performance to be expected from the new civil GPS signal. In the last chapter of this paper we will discuss the L1/L2 signal anomaly of SVN49 and present first measurements and analyses for the L1.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	1544 - 1551
Cite this article:	Erker, S., Thölert, S., Furthner, J., Meurer, M., Häusler, M., "GPS L5 "Light's on!" - A First Comprehensive Signal Verification and Performance Analysis," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 1544-1551.
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