Research And Implementation Of Narrowband Interference Suppression Technology In Satellite Navigation Receiver

Global satellite navigation system can provide precise positioning, speed measurement, timing and other services, it has many characteristics such as real-time, continuous and all-weather. Global satellite navigation system is not only widely used in public services field such as railway, highway, shipping and communication industry, but also used in military field such as aerospace, cruise missiles, individual equipment and warships, it is an important guarantee of economic security and defense security for a country. Since the modulation frequency and modulation characteristics of satellite navigation signals are public, and the weakest power of navigation satellite signal only is160dBw when it reaches the Earth’s surface, as a result, it is vulnerable to a variety of signals, for example, suppress jamming from the man-made and potential electromagnetic interference from the environment. In the context of information age nowadays, electronic warfare has become an important part of the war, the ability to provide effective navigation in complex electromagnetic environment is the key to the outcome of a war. Therefore, the study of interference suppression technology in satellite navigation receiver has important significance.First of all, the development situation of domestic and foreign narrowband interference suppression technology in time-domain and transform domain are summarized in this paper, and the major global satellite navigation system such as GPS, GLONASS, GALILEO and BeiDou are analyzed and compared, meanwhile, artificial and potential interference signal are provided. Then, based on analyzing the basic composition principle of satellite navigation receiver, the process of generating GPS signal and the C/A code is described in detail, and the principle of measureing the distance with TOA and positioning with PRN is illustrated in satellite navigation receiver. According to the principle of narrowband interference suppression in satellite navigation receiver, the application of window function is analyzed, and the formula of SNR loss caused by signal adding window is deduced. Next, based on the principle of selecting window function, inverse windowing and overlap-combination algorithm are provided, meanwhile, the method of inverse windowing algorithm combined with overlap-select algorithm for narrowband interference suppression is proposed, the method of choice threshold for narrowband interference suppression based on fixing threshold and adaptive threshold is described, the algorithm of signal truncation error in the hardware implementation and the method of Dither that improve signal truncation error are studied. Finally, the function of narrowband interference suppression is achieved by using VHDL language in FPGA hardware environment, hardware and software development environment realizing narrowband interference suppression is described, where the development tools, VHDL hardware description language and Xilinx FPGA processors arc included. Based on the process of implementing narrowband interference suppression module, the implementation method and design process for FFT and IFFT calculation module, windowing and anti-windowed module. ROM memory modules and overlapping selection module are analyzed, and the function, entity structure and implementation process are described in AGC module. At the same time, the performance and function of narrowband interference suppression module are tested under different conditions by using ChipScope and Modlesim testing platform, and based on the principle of signal truncation; the signal truncation is tested.