Hardware In The Loop Simulation Of Complex Radar Target Echo Signal Based On Scattering Center Model

Wideband radar has high range resolution and far detection range because of its large time and bandwidth product,which has been widely applied,especially in the field of national defense.As the main test means of wideband radar system,the hardware in the loop simulation technology of wideband radar has become a hot spot of research at home and abroad.For the problem of large computation and poor real-time performance in the reconstruction process of wide-band radar target echo,it has great theoretical and practical value to study and research the high real-time and high-precision wideband radar echo reconstruction technology.Firstly,this thesis studies the electromagnetic scattering characteristics of wideband radar target.The principle and mechanism of electromagnetic scattering of wide-band radar targets are studied,and the modeling and simulation experiments of electromagnetic scattering characteristics of wide-band radar target are carried out.Based on the scattering center model of electromagnetic scattering of wideband radar targets,Parameters extraction simulation experiment of complex radar targets is carried out based on GTD scattering center model.Secondly,this thesis studies the mathematical model of wideband radar target echo.For the problem of large computation and high resource consumption in wideband radar target scattering characteristic modulation algorithm,a fast algorithm of wideband radar echo reconstruction using LFM sub pulse is presented.The algorithm divides the wideband radar transmitting pulse signal into several segments,and these segments are treated as narrow and short pulse signals.The echo data of each sub pulse are calculated by the algorithm,and then the wideband and full pulse echo signals are reconstituted.The algorithm greatly simplifies the complexity of real-time reconstruction of wideband radar echo,and has the advantages of small computation,high accuracy and good real-time echo reconstruction.Thirdly,this thesis analysis the shortcomings of large radar target Doppler frequency modulation method,and the improved look-up table based on FPGA is used to generate the wideband radar target's Doppler frequency.This algorithm combines the look-up table method with the calculation,which greatly reduces the storage resources of the look-up table method,saves the memory resources,which is suitable for implementation in the FPGA.Through the simulation experiment,it is proved that the algorithm solves the problem of high storage resource consumption by the look-up table method,and has high accuracy and real-time performance.Fourthly,hardware implementation of wideband radar echo reconstruction algorithm based on the scattering center model is studied and designed.The wideband and low spur DRFM system is used as the hardware implementation platform of the echo reconstruction algorithm.According to the resources in the DRFM system and the requirements of system,digital orthogonal mixing module,eight channel parallel FIR low-pass digital filter module,scattering characteristics of modulation module,wideband Doppler information generation and digital up conversion module are mainly designed and simulated in detail.The experimental verification and analysis of the echo reconstruction algorithm based on DRFM system are also carried out.The experimental results show that when the instantaneous bandwidth of radar signal reaches 1GHz,the spurious performance of echo reconstruction signal is better than-45 dBc,which shows the correctness and real-time performance of the wideband radar echo reconstruction method based on scattering center model designed in this thesis.