Research On Navigation Anti-jamming System Based On Multi-beamforming Algorithms And Its Implementation

Global navigation satellite system transmits navigation satellite signal through the satellites, and the signals can be employed to position, navigation and timing services for the users from the ground or space. The extremely low power of the navigation satellite signal and lots of interference in the space attribute that the navigation receiver is easily affected by the interference signal, and then the receiver cannot work in a good state. At the same time, research on the navigation anti-jamming technology has been enhanced all over the world because of the dominating position of the America’s Global Positioning System(GPS) and its important military position for national defense. Nowadays, the anti-jamming methods based on adaptive array signal processing have been used widely. So, the application of array signal processing is studied in this thesis.Firstly, the beamforming algorithm for anti-jamming is presented, and the performance comparison between the beamforming algorithm and the traditional adaptive filtering algorithm is analyzed under different constraint criterion. The performance of the generalized side-lobe cancellation algorithm is also taken out through computer simulation. Simulation results indicate that beamforming algorithm can obtain a main lobe gain in the direction of the target signal and also a nulling point in the direction of the interference signal.Secondly, the overall design of the system is considered and the hardware implementation of the signal processing board is analyzed in detail. Then, band-pass filter and Hilbert filter which are needed in the system are also discussed.The hardware implementation of the digital multi-beam algorithm is studied following. The cost of the hardware resources, the degree of the difficulty, and the algorithm performance are all analyzed. The Least Mean Square(LMS) is chosen for the adaptive digital multi-beam processing. The correctness of the multi-beam algorithm of the hardware implementation is verified through the floating point and fixed-point simulations.Finally, the outdoor experiment is conducted by using the existing navigation anti-jamming system to further verify the anti-jamming capability of the navigation satellite system.