Research On GNSS Anti-jamming Technology Based On Mixed Signals Separable Mechanism

Global Navigation Satellite System(GNSS) has gradually developed into a high-precision navigation system with characteristics of globalism, real-time and all-day, which has been widely used in the military and civilian fields. GNSS signals are susceptible to intentional or unintentional interference, so the anti- interference ability of the user receiver has become a key issue to ensure navigation system work properly. Air anti-jamming technology has higher demand for the prior information of signal, such as antenna pointing, direction-of-arrival(DOA), etc, so that there is a big limitation for air anti-jamming technology. To address this problem, this paper adapt blind source separation(BSS)to separate GNSS signal from mixed signals to achieve anti-jamming in the case of unknown priori information of signals and transmission. In this paper, the main contents are as follows:1. According to the characteristics of GNSS and interference signals, the anti-jamming ability of GNSS and the effects of interference worked on GNSS are studied separately. Simulation results show that there was a great impact on the GNSS acquisition ability from interference signals, and it is important to eliminate the effe cts on GNSS acquisition from jamming signals.2. As the traditional separation algorithm with fixed values is sensitive to the initial matrix, the decreasing factor is introduced to improve the traditional fixed-point separation algorithm The simulation results show that the separation algorithm iterative process is more smooth and stable, GNSS signal after separation is closer to the original GNSS signal. Simulation results show that GNSS signal separation algorithm can achieve the separation of GNSS signa l and interference signal.3. Currently, separation algorithms are suitable for noiseless signal separation process, but it is inevitable to consider the impact of real transport channel for GNSS. This paper, first analyzed the effect on separation result by noise, and then proposed a separation algorithm by de- noising and eliminating bias.Simulation shows that there was a serious impact on separating from noise with the decreasing of SNR.. There was higher similarity and smaller PI value by the proposed separated algorithm than those generated by traditional algorithm, and the separation result has improved significantly.4. The ambiguity of separated signals is studied in detail. Researches show that the separated algorithm with minimal distortion can eliminate margin ambiguity better. The GNSS signals recovered from the observed signals is closer to original GNSS. For the problem of traditional Murata algorithm, this paper proposed a corresponding improvement algorithm. Simulation shows that the similarity coefficient of obtained GNSS signal by the proposed algorithm is much closer to 1 and the mean square error(MSE) is smaller, indicating that the separated effect by the proposed separated algorithm is much better.5. With the help of MATLAB GUI tools to complete the design of software simulation platform for GNSS anti-jamming, the separated effect and anti-jamming performance of algorithm is studied and provide visualization software simulation platform and analysis method for future research.