Development of a Flexible Receiver for Galileo Navigation Signal Verification

Stefan Berberich, Peter A. Krauss and Andrei Botchkovski

Abstract:	Based on the prototype of a spaceborne Galileo navigation signal receiver [2], Astrium will develop an extremely flexible navigation signal receiver for GAFLEX. It will be possible to receive QPSK modulated signals in the L1 and L2 band with selectable code types (Gold, Kasami, …), code rates from 1.023 MHz to 10.23 MHz with code lengths from 1.023 kChips to 16.384 kChips, including truncated code lengths. Optionally, the PRN signal can be square-root raised cosine (SRC) shaped and/or can have a binary offset carrier (BOC). The navigation data bit rates can vary from 50 bit/s to 1.5 kbit/s and can be convolutionally encoded. Using our experience on GPS receivers for space [1], main parts of signal processing such as down conversion to baseband, code and carrier generation and code and carrier correlation to reduce the received signal bandwidth are implemented in hardware to improve the signal-to-noise ratio conditions and to decrease the processor load. Signal acquisition, tracking and data extraction are implemented in software to match the requirement of the GAFLEX receiver. A quasi-optimal delay lock loop which operates over the entire split spectrum signal at once will be implemented for the demodulation of BOC encoded signals. Digitalization and final down-conversion of the navigation signal is carried out at an IF of 70 MHz. The RF front-end uses one down conversion stage for every L band frequency. Given the fact that this receiver is operated on ground, the digital hardware platform will be a commercially available multi-DSP system. However, the RF front-end as well as dedicated functions implemented in hardware will be supplementary in-house development. Further upgrade of the receiver to a space qualified hardware for future space application will remain an option. This paper will present details of the new design as well as simulation results. Also covered will be a detailed investigation of the influence of SRC shaped encoded spread spectrum signals on the accuracy of the raw data measurements.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	758 - 767
Cite this article:	Berberich, Stefan, Krauss, Peter A., Botchkovski, Andrei, "Development of a Flexible Receiver for Galileo Navigation Signal Verification," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 758-767.
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