Applied Research Of A Communications Anti-jamming System

Adaptive sidelobe cancellation technique is an important technology,it cansuppress blanket jamming effectively.The paper studies some problems aboutadaptive sidelobe cancellation technique on the existing platform,Meanwhile,it alsoprovides support for the follow-up work.The main works of this dissertation are as follows:1、The author learns the theory of array signal processing, including the uniformlinear array, uniform rectangular array,receiving signal model of any array andadaptive beamforming technology.2、The author learns the theory of adaptive sidelobe cancellation technology,including the model of the array antennas and mathematical model of sidelobecancellation, the definition of cancellation ratio and pattern.3、The paper studies the adaptive algorithm, considers the computationalcomplexity, convergence performance, hardware implementation. We finally decideto adopt the combination of SMI and LMS,which improves calculation speed as wellas simplifies hardware implementation.4、The paper designs the visual simulation platform. In order to study andanalyse the performance of the system on a single platform,the paper use MATLABGUI tools to design a visual simulation platform,which can solve severl problemsincluding the performance of the algorithm, positions of the antennas, non-idealfactors and other issues.5、The paper also studies the positions of auxiliary array.In the adaptive sidelobecancellation system, the positions of auxiliary array are very important.The papersummary some key points about it,and verify on the simulation platform, finally wefind the optimal position of array elements to meet practical requirements.6、 In the engineering, there are many undesirable factors, including theamplitude and phase discordance,A/D quantization and so on. It is of significance toanalyse them.The paper analyses the impact of the Digital Phase Shifters and DigitalAttenuators, the amplitude and phase discordance,meanwhile,we verify on the simulation platform.