Analysis of an Ionospheric Free Vector Tracking GNSS Software Defined Radio

C. Anderson Givhan, Scott M. Martin

Abstract: Vector tracking architectures, which utilize the user PVT estimate to track the incoming signals, have been shown to be more robust than traditional GNSS software defined radio architectures. With the recent addition of new civil signals to the GPS constellation in the L2 and L5 frequency bands, VDFLL receivers can now utilize multiple civilian GPS signals. While the appeal of frequency diversity for the vector tracking user is mostly for the added robustness to frequency-based interference, there is now also the potential for the mitigation of frequency-based PVT errors such as those caused by the ionospheric delay. Traditional receiver architectures use carrier phase measurements to remove ionospheric errors and provide precise PVT solutions, which requires the use of PLLs which are most subject to loop failure in degraded signal environments. Previous works have used the VDFLL receiver to aid phase lock loops for increased robustness or have used VDPLL architectures that rely on external aiding for RTK corrections to maintain lock. This work presents an ionospheric error corrected GPS L1 C/A and L5 VDFLL receiver that has no reliance on the weaker PLL or external aiding sources. The work outlines a receiver that provides an ionospheric corrected vector tracking range residual to the navigator for better tracking of the true position. The work also discusses the effects of the vector tracking receiver being updated from the true antenna solution rather than the ionospheric delay biased solution that corresponds to the maximization of the signal and replica correlation. The presented receiver is tested on live sky and simulated data for positioning performance in the presence of dynamics and rapidly changing received power; it shows itself to be capable of better removing frequency-based errors than compensated single frequency systems while still maintaining a level of robustness expected of vector receivers.
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: 3972 - 3981
Cite this article: Givhan, C. Anderson, Martin, Scott M., "Analysis of an Ionospheric Free Vector Tracking GNSS Software Defined Radio," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 3972-3981. https://doi.org/10.33012/2023.19418
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