Research On The Jamming Against High-performance GPS Receivers

Due to powerful anti-jamming capability, high-performance GPS receivers are widely used in the military field. Its anti-jamming capability is mainly because the use of adaptive nulling antennas. Therefore, this thesis studies on the interference technology against high-performance GPS receivers with adaptive nulling antenna s. The main contents of this thesis are summarized as follows:1. The fundamental principle is studied that the adaptive nulling antennas technique improves the interference tolerance of GPS receivers greatly. The accurate definition of GPS receivers' interference tolerance is also given. A set of system simulation methods of testing high-performance GPS receiver's interference tolerance is proposed.2. The GPS receiver with adaptive nulling antennas is realized with simulation and the corresponding interference model is established. Moreover, the performance characteristics of different interference patterns are analyzed and the reason on how to select the interference is also provided.3. On the basis of deriving LMS algorithm, its performance characteristics, especially its convergence, are analyzed. And at the same time, a novel kind of flashing interference is designed by making use of the convergence drawback of LMS algorithm. This flashing interference still with high residual power when it through the adaptive nulling antennas. Simulation results shows that this interference pattern has better jamming performance when it is used to interfere some GPS receivers which have some design defects regardless of using adaptive nulling antenna technology. However, this flashing interference has great limitation, it has poor performance when its target is well-designed GPS receiver with adaptive nulling antennas.4. Under the condition of different numbers of interferences sources(i.e., 1, 2, 3, 4), the influence of interference sources' distribution on the interference performance is studied and analyzed in terms of the pitch angle and azimuth angle. The results show that the layout of interference sources is to a great extent to affect the interference performance,that increasing the number of interference sources may not enhance the interference performance with taking the layout of interference sources into account, and that in the case of the good interference layout, when the number of interference sources changes from 1 to 3, the addition of one interference source results in the performance improvement of Xd B or so, but there will be performance enhancement of more than Xd B if the number of the interference sources increases from 3 to 4.