Research And Implementation Of The Space And Frequency Adaptive Processing Algorithm For The Navigation System

The satellite navigation system is widely used in various fields, and its development prospect is full of potential. Meanwhile, the vulnerability of navigation signal makes itself can be easily affected by electromagnetic radiation or intentional interference, which may make the receiver work abnormally. Therefore, the research of anti-interference technology of navigation signal has become an active field today, and more attention has been paid to it at home and abroad. The anti-interference algorithms, based on array signal processing, are most applied in the navigation anti-interference system. The space adaptive processing and the space time adaptive processing algorithm are the most common ones; while the application of the space frequency adaptive processing in navigation anti-interference system is still in the initial stage. In this background, the performance of the space frequency adaptive processing algorithm is analyzed and the implementation of the algorithm is realized in the FPGA chip of the anti-interference system in this paper.Firstly, several common anti-interference technologies are introduced. This paper points out that space time and space frequency adaptive processing algorithms are able to distinguish different signals by space angle and frequency domain, which results in better performance of anti-interference. After that, this paper introduces the model of array and the power inversion algorithm which is used to solve the weight value. Then, based on power inversion, the anti-interference performances of the space, space time and space frequency adaptive processing algorithms are analyzed through MATLAB simulation. The simulation results show that the space time SMI(sample matrix inversion) and the space frequency SMI algorithms performs better than other algorithms. However, the space frequency SMI algorithm has much less matrix computational complexity than the space time SMI algorithm, which makes it much easier to be implemented in hardware.Secondly, the overall structure of the navigation anti-interference system is introduced, and the overall implementation scheme of the space and frequency SMI algorithm in FPGA is proposed. Then, the design details of primary modules are described explicitly, and each of them is verified though the simulation of Modelsim. Finally, the whole space frequency SMI algorithm module is compiled in Quartus II, and the hardware resource consumption is analyzed though the compile report.At last, after downloading the code of the space frequency SMI algorithm into the FPGA chip on the digital signals processing board of the anti-interference system, experiments in the outfield are carried out to verify the anti-interference performance of the space frequency SMI algorithm. The performances of the space frequency SMI algorithm and the space time LMS algorithm are compared on base of the experiments results. The result of the comparison shows that the space frequency SMI algorithm and the space time LMS algorithm both have their own advantages and disadvantages in in practical application. In the end, the problems encountered and the experiences earned in the course of the experiment and are summarized.