M.M. Kanouj1, A.V. Klokov2

1,2 NR TSU (Tomsk, Russia)

In conventional GPS receiver the carrier tracking system is the key stage that keeps the receiver locked to radio navigation parameters (RNP) of the received signal. The most commonly used approaches to the tracking system are: phase lock loop (PLL), frequency lock loop (FLL) and FLL-assisted-PLL. The main limitation of the above approaches is that their performance deteriorates when working with weak signals, and under high dynamic conditions. In recent years, Kalman filter (KF)-based tracking loop architectures have gained much attention due to its robust and better performance compared with conventional architectures. This paper proposes an algorithm of unscented Kalman filter (UKF) to estimate RNP in a GPS receiver tracking system. The proposed tracking loop is responsible of estimating the following RNPs: carrier phase, Doppler frequency and its change rate. The proposed tracking loop is designed to work in some low dynamic and weak signal circumstances such as indoor pedestrian and urban vehicle navigation. The RNP estimates obtained in the proposed method are compared to similar estimations of a conventional tracking (FLL-assisted-PLL) and a linear KF-based tracking methods. Monte Carlo simulations are performed to compare the statistical characteristics of RNP estimates in the three tracking methods. Simulations are performed in terms of the tracking probability, sensitivity, accuracy and bit error rate (BER). Compared with the conventional and KF-based tracking methods, the UKF-based tracking method improves the tracking sensitivity by 9 dB and 3 dB, respectively. It also shows higher accuracy and lower bit BER than the other two methods.

Kanouj M.M., Klokov A.V. Comparative statistical analysis of radio navigation parameters estimates in a GPS signal tracking loop with various methods of its construction Radiotekhnika. 2022. V. 86. № 3. P. 46−57. DOI: https://doi.org/10.18127/j00338486-202203-05 (In Russian)

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