Radar Echo Simulation And FPGA Implementation In The Sea-Chaff Jamming Scene

Simulation and computational research of radar echoes in complex sea surface electromagnetic interference environment has important theoretical significance and application value in the fields of radar target characteristics,target feature identification and anti-interference performance evaluation and optimization.The research work on radar echo simulation methods for sea surface environment and its overhead chaff passive interference and ship targets can help analyze the echo characteristics of sea surface ship targets and provide theoretical and data support for chaff interferer development.In this dissertation,we focus on radar echo simulation and FPGA(Field Programmable Gate Array)implementation methods for sea surface scenarios with complex electromagnetic environment to simulate the realistic technical requirements.The main innovation are as follows:1.The dissertation proposes a 3-D spatial-temporal correlation expansion sea clutter statistical simulation method is proposed,which can simulate the sea clutter data of larger area and longer observation time using small size data,and the calculation results have consistent spatial-temporal correlation and amplitude probability density with the small size sea clutter data obtained from the electromagnetic model.A parallel structure based on3 D space-time correlation extended sea clutter statistical simulation method applied to FPGA platform is presented.At first,pipelined parallel optimization is performed for the required basis functions.According to the working mode of FPGA and data read/write bottleneck,the structure of reducing access to off-chip memory and improving data throughput rate is proposed,and the simulation results are compared with the PC platform simulation results and the original data obtained from the electromagnetic model The algorithm is compared with the simulation results of PC platform and the raw data obtained from the electromagnetic model,to verify the feasibility of porting the algorithm to FPGA platform and to achieve higher computational efficiency.2.The dissertation presents a systematic modeling of the diffusive motion and electromagnetic scattering characteristics of chaff clouds,mainly including three aspects of the simulation of the diffusive motion of chaff clouds in the low-altitude atmosphere,electromagnetic scattering characteristics and the simulation of radar echoes of chaff clouds considering mutual coupling effects.A chaff aerodynamic model specifically for sea surface and low altitude dense atmosphere use scenarios is proposed,and a simulation model of chaff cloud diffusion motion considering spin is established.A six-degree-offreedom model simulating chaff spin is introduced based on chaff force analysis to solve the problem that the chaff attitude angle of the existing motion model is simulated by random numbers with fixed probability density3.The dissertation proposes a coordinate rotation-based chaff cloud voxel partitioning method and a CPU-parallel optimized line moment method for electromagnetic scattering simulation model of high-density chaff clouds.For a high-density chaff cloud of 10 million magnitude,the mutual occlusion and attenuation effect of its internal elements on the incident electromagnetic waves cannot be neglected,and the mutual coupling effect is also the mechanism of the chaff cloud’s effect on radar’s occlusion-type interference or washout-type interference.Compared with the traditional octree algorithm,the proposed coordinate rotation-based chaff cloud voxel partitioning method can significantly compress the time consuming to calculate the scattering characteristics of chaff clouds in the tens of millions by optimizing the algorithm of the line moment method and CPU parallelism,and consider the mutual occlusion,attenuation and mutual coupling effects among the elements inside the high-density chaff cloud,which can make the simulation more closely match the actual number of elements contained in the chaff cloud.The chaff cloud diffusion and density distribution,scattering field spatial distribution,echo distance image and Doppler spectrum characteristics are calculated for the single multi-shot release and multiple multishot release scenarios of the hybrid chaff strip projectile according to the sea surface use.Fast voxel partitioning can be performed for higher orders of magnitude of chaff elements in a larger area,and scattering characteristics and attenuation of the signal can be obtained for each subunit.The chaff cloud motion model and electromagnetic scattering calculation method lay the foundation for the subsequent radar echo simulation of complex interference scenes on the sea surface4.For the simulation of complex electromagnetic interference environment on the sea surface,a method to calculate the radar echoes in the whole spatial large-scale area is proposed based on the coupled electromagnetic characteristics of the sea surface environment,ship targets and chaff cloud curtain wall.Firstly,the scattering characteristics of sea surface and ship targets are calculated,and then the voxel partitioning of the chaff cloud is carried out according to the sea surface element division,and the attenuation and shielding effects of the chaff cloud on different regions are calculated,so as to calculate the complex environment electromagnetic scattering characteristics and radar echoes of the whole space region of sea surface-target-chaff cloud more reasonably,and provide theoretical basis and simulation data for radar anti-interference research and new system passive interference research.It provides theoretical basis and simulation data for radar anti-interference research and new system passive interference research.The dissertation improves the electromagnetic simulation method for sea surface complex interference environment,simulates 3D space-time correlated sea clutter and chaff cloud radar echoes using FPGA platform,establishes the radar echo simulation method for passive interference of chaff cloud above the sea surface,and proposes a complete computational flow from chaff dynamic model to electromagnetic simulation.For the actual sea surface scenario,the radar echo simulation method of sea surface,chaff cloud and ship complex scenario is proposed by combining the ideas of surface element and voxel discretization,and the radar echo of typical sea surface complex interference scenario is simulated and analyzed according to the interference strategy.