Robust Wavelet Variance-Based Stochastic Analysis of Instantaneous Code Phase-Based Oscillator Instability

Chrysostomos Minaretzis, Yiran Luo, Stéphane Guerrier, Naser El-Sheimy, Michael Sideris

Abstract: Modeling a Global Navigation Satellite System (GNSS) receiver clock instability is crucial to advancing GNSS-based navigation systems, especially regarding low-cost devices. This work proposes a way to obtain an insight to the drift that characterizes Local Oscillators (LOs) of GNSS receivers by using a raw GNSS baseband signal, namely the instantaneous code phases and then model its random behaviour using a state-of-the-art stochastic modeling framework, the Generalized Method of Wavelet Moments (GMWM). First, a GNSS Software-Defined Radio (SDR) is used to process three types of IntermediateFrequency (IF) GPS signals (i.e., L1 C/A, L5 data, and L5 pilot) and generate the respective code phase measurements, which are synthesized by using the LO from a GNSS frontend. Then, a pre-processor computes clock bias errors by subtracting the code phases from their references. Finally, the single-difference results of the pre-processor outputs, meaning the first order change increments of the previously computed clock bias errors, are inputted into the Robust GMWM (RGMWM) framework, which offers a stochastic modeling solution that is partially protected by the influence of outliers in the data at hand. The suggested methodology was tested by carrying out real-world experiments under open sky conditions, which validated the effectiveness of the RGMWM in stochastically modeling the LO instability using the instantaneous code phase of GNSS signals. In addition, a new type of sinusoidal noise has been identified in the input data computed from the GPS L1 C/A tracking and quantified via the RGMWM, while the L5 signals appeared to be unaffected by such noise type. This finding has the potential to contribute in the development of more advanced GNSS receivers by leveraging this more reliable modeling in either the baseband processors or navigators in the future.
Published in: Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023)
September 11 - 15, 2023
Hyatt Regency Denver
Denver, Colorado
Pages: 3005 - 3019
Cite this article: Minaretzis, Chrysostomos, Luo, Yiran, Guerrier, Stéphane, El-Sheimy, Naser, Sideris, Michael, "Robust Wavelet Variance-Based Stochastic Analysis of Instantaneous Code Phase-Based Oscillator Instability," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 3005-3019. https://doi.org/10.33012/2023.19361
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