A jamming tolerant BeiDou combined B1/B2 vector tracking algorithm for ultra-tightly coupled GNSS/INS systems

All Global Navigation Satellite System (GNSS) signals could be easily disturbed by intentional jamming in hostile environment. To deal with these threats, ultra-tight GNSS/INS integration has been developed. However, most of them have focused on the single-frequency system. This paper proposes a novel vector tracking strategy, which uses pre-filters to combine both BeiDou B1 and B2 signals tracking simultaneously and then feed the tracking for the ultra-tightly coupled GNSS/INS systems. The Doppler shift relationship between B1 signal and B2 signal has been analyzed to combine the replica carrier signals tracking of different bands. Moreover, the inherent relationships between INS states and replica code phase and carrier frequency biases have been described based on construction of the correlation model. Finally, semi-physical simulation results indicate that the proposed ultra-tight integration approach based on BeiDou combined B1/B2 vector tracking algorithm can significantly improve the receiver's tracking ability and navigation performance comparing with the conventional ultra-tight integration approach under the signal jamming environments.