Wideband Dual-Channel RF Record and Playback for Multi-Constellation Analysis

M-A. Fortin, I. Ilie, D. Fortin, K. Mollaiyan, R. Jr. Landry

Abstract:	This paper demonstrates the Global Navigation Satellite Systems (GNSS) performance in terms of reliability and reproducibility of an RF Record and Playback system in three distinct steps: 1) baseband analysis of the recorded I/Q samples; 2) receiver measurements comparison and 3) with respect to a true Real Time Kinematics (RTK) solution in both static and dynamic modes. The mathematical post-analysis of the recorded I/Q samples has shown that the phase relationship is maintained from one band to another, due to the <1 ns time synchronization and highly accurate phase coherence between recording/playback channels below 7 °. Once this thorough validation process completed, it then compares the benefits of “signal diversity” in different GNSS receivers in terms of frequency, constellation and Satellite Based Augmentation Systems (SBAS) differential corrections. Such signal diversity is achieved by submitting a receiver to the same recorded GNSS reference signals multiple times, using Averna’s URT® 5.2.2 RF test platform, which now supports multi-channel Record and Playback of up to 50 MHz on three wideband channels to capture the complete GNSS band. In this paper, only GPS and GLONASS signals on both the L1 and L2 bands are targeted, as these are the only operational (or about to be operational) constellations today. Consequently, a Dual-Channel RF Record and Playback system is used. Because of inherent thermal noise and receiver clock instability (i.e. bias, drift, jitter), the estimated solution for a given time stamp will vary from one trial to another according to the receiver's performance. The average of this variation will tend towards zero as the solution duration increases. Hence, a 1 m average for 20 min. tests are conclusive and within receiver performance. Longer played back results will be included in an upcoming publication. Nevertheless, experimental results are within receiver performance. In addition, the Dilution of Precision (DOP) decreases as constellations are combined. Hence, the described Wideband RF Record and Playback architecture is the ideal (mobile) tool for sensing, analyzing and reliably repeating real-world multi-constellation signals.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	879 - 891
Cite this article:	Fortin, M-A., Ilie, I., Fortin, D., Mollaiyan, K., Landry, R. Jr., "Wideband Dual-Channel RF Record and Playback for Multi-Constellation Analysis," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 879-891.
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