Optimal Hopping Patterns And Their Applications In MIMO-SAR Systems

With the research on Synthetic Aperture Radar(SAR)and Multiple Input Multiple Output(MIMO)radars,demand of resolution and requirements of anti-interference for radars are getting higher and higher.Therefore,the research on orthogonal signal of MIMO-SAR is becoming more and more important.This is also one of the topics of great concern in the world today.This thesis introduces the principles of radar,SAR and MIMO radar,and focuses on the principles and characteristics of MIMO-SAR and distributed MIMO-SAR.The Costas arrays has an ideal auto-correlation property,so it is often used to design the signal of the MIMO-SAR system,but the Costas arrays does not have an ideal cross-correlation performance.This thesis introduces the algebraic structure of the Welch Costas sequence,and based on this,proposes a method for constructing the optimal frequency hopping pattern with ideal auto-correlation and cross-correlation properties based on the Welch Costas arrays using a two-dimensional cyclic shift method.In the thesis,the optimal frequency hopping pattern is constructed by a Welch Costas sequence with a gap line,and the distributed MIMO-SAR signal can be designed to obtain a "drawing pin" ambiguity function,which is better than the general radar signal.Based on the radar ambiguity function,this thesis discusses the performance index of the radar signal and the factors affecting the imaging resolution,so as to establish the echo model of the designed signal.In this thesis,the mathematical model of frequency hopping spread spectrum signals and the construction method of distributed MIMO-SAR signals based on the optimal hopping pattern is introduced,and carrying out simulation analysis.Simulation results show that radar signals with better auto-ambiguity and cross-ambiguity can be obtained by designing distributed MIMO-SAR signals with the optimal frequency hopping pattern,which is of significance for constructing distributed MIMO-SAR signals.The research results have important reference value for studying MIMO-SAR.