Research On Diversity Gain Of Wideband Radar And Target Detection

The performance comparison between Coherent Accumulation(CA)and non-coherent Accumulation(NCA)is a traditional and relatively complex problem for radar workers.Coherent Accumulation has a high SIGNal-to-noise ratio gain.Although incoherent accumulation has accumulation loss,it can effectively suppress the fluctuation degree of echo when it is accumulated between unrelated samples.Based on this,scholars put forward the concept of diversity gain:the suppression effect of irrelevant signal accumulation on fluctuation loss is used to improve the detection performance of the target,and according to the diversity dimension,it can be further subdivided into frequency diversity,Angle diversity(spatial diversity),etc.On this basis,the concepts of"broadband frequency diversity gain"and"Angle diversity gain of moving target"are analyzed in depth,and specific feasible quantitative calculation methods are given.The specific accumulation method and processing algorithm of moving target detection technology are improved and optimized.The main work and innovations are as follows:In chapter 2,a unified target RCS model with differentχ~2 distribution of degrees of freedom is established and a wideband radar echo model are established.Based on the traditionalχ2 distribution target,the concept of wideband target RCS is redefined with the idea of frequency/wideband diversity,and the wideband radar echo model is built on this basis.In chapter 3,the broadband frequency diversity gain and optimal scale accumulation are studied.Firstly,the frequency correlation of wideband target is analyzed and the equivalence between frequency de-correlation and range de-correlation is illustrated.After quantitative analysis of accumulation loss and fluctuation suppression of incoherent accumulation between range elements,a quantitative calculation method of broadband frequency diversity gain is presented.Based on the unifiedχ~2 target model in Chapter 2,the detection models under wideband frequency diversity for three types of Swerling targets are established,and monte Carlo simulation experiments are designed to verify the correctness of the quantization calculation method of wideband frequency diversity gain.Under different detection and false alarm probability requirements,the optimal detection bandwidth and optimal accumulation scale are calculated by using the quantitative analysis method established in this paper for different Swerling target types.In chapter 4,Angle diversity gain and optimal accumulation of moving target are studied.Firstly,the Angle correlation analysis of target echo is carried out,and the experimental verification and analysis are carried out.On the basis of incoherent accumulation loss and undulating loss gain in Section 3.4,the quantization calculation method of Angle diversity gain is given.Monte Carlo simulation experiments are designed to verify the correctness of the quantization calculation method of Angle diversity gain of moving target.By using this method,the gains of the best and worst hybrid accumulation are calculated,the gain intervals of the hybrid accumulation under different target models are given,and the optimal hybrid accumulation mode is given for different pulse numbers.In chapter 5,the fast algorithm of long time coherent accumulation for moving target detection is studied.Firstly,traditional methods such as Keystone transform and Radon Fourier transform are studied.On the basis of Radon Fourier variation,a moving target detection algorithm based on Two-Steps Accumulation RT(TSA-RT)and fast RT algorithm based on sub-pulse correction(SPMC-RT)were proposed.SPMC method was compared with existing methods in terms of operation steps,computation amount and accuracy,and simulation experiments were designed to verify the algorithm.The superiority of the algorithm is proved.