Research On Key Technologies Of The Anti-jamming GNSS Receiver

GNSS receiver is the key component to promote marketization and industrialization of the satellite navigation system. With the implementation of globalization strategy of BDS-II,Chinese satellite navigation industry is facing fierce competition from all over the world. In this situation, the key technologies of the navigation receiver in the current spread-spectrum scheme should be well studied to design low complexity, high sensitive, high dynamic and robust anti-jamming GNSS receivers which will benefit the sustainable development of BDS. The research in this paper mainly involves three aspects: jamming detection, signal acquisition and carrier tracking. The main work and innovation points are as follows.1. A quadratic estimation algorithm is proposed to estimate sweep interference parameters in a strong noise. In this algorithm, the mixed coherent accumulation and PMF-FFT are applied to compress search interval and reuse hardware resources. Simulation shows that the accuracy of the proposed algorithm is close to CRLB and the complexity as well as the hardware consumption is much less than that of the frequency rate test algorithm and joint estimation algorithm based on interpolation.2. After proposing a complexity optimization method of traditional average periodogram algorithm, this paper proposes an improved average periodogram acquisition algorithm for the acquisition of coherent DSSS signals with low SNR and high dynamic.This algorithm adjusts the starting frequency offset of each time window around zero point by utilizing the frequency relationship of data segments and Rotating shift characteristics of the FFT. The simulation shows that compared with the traditional periodogram algorithm,the improved algorithm has better estimation accuracy and much lower computational complexity.3. A block acquisition algorithm based on parallel interval estimation is proposed for DSSS signal with low SNR and non-coherent data modulation where the existence interval of data modulation offset is estimated in parallel with invalid data section abandoned against possible bit-flip. Both analysis and simulation demonstrate that by adjusting key parameters to match the requirement of false alarm and detection probability, acquisition time and SNR, the proposed algorithm achieves good performance with low computational complexity and resource consumption.4. A high dynamic data-modulated carrier phase tracking algorithm based on adaptivenested Kalman filter is proposed which combined Kalman filter with "current" statistical model corresponding to the relative movement of the navigation satellites and receivers.The proposed algorithm takes the prediction of relative acceleration as the mean of the modified Rayleigh distribution to determine the probability distribution of current acceleration and choose corresponding filter parameters. Simulation shows that compared with the extended Kalman filter algorithm, the proposed algorithm has much higher robustness and precision in high dynamic data-modulated carrier phase tracking without increasing hardware resources.