Research On Dim Target Detection Technology Based On External Transmitter Of Geostationary Earth Orbit Satellite

This thesis has done a certain research on the weak target detection technology in the external transmitter radar system of geostationary earth orbit satellite.Firstly geostationary earth orbit satellite is used to emit signals for illuminating the target in the system,and then for detecting the targe the ground-based receiving device is used to receive the target’s echo.However,because the distance between the geostationary earth orbit satellite and the target and the distance between the target and the receiving device is long,SNR of the target echo received by the receiving device is low.In order to obtain SNR for detecting target,it is usually necessary to accumulate the echoes for a long time,but the long-time coherent accumulation will bring about the problems of acrossrange-unit migration and across-doppler-unit migration.In response to this problem,some researchs have been done on the long-term accumulation algorithm.Under this system,target detection points are prone to dot-trace expansion in multiple dimension,which leads to excessive data volume for subsequent signal processing.To solve this problem,some researches have been carried on plots centroid.The main research contents of this thesis are as follows:1.First,the geometric model and signal form of the external transmitter of geostationary earth orbit satellite radar system are given,and the echo signal model and characteristics are analyzed.As the same tine,the reasons for across-range-unit migration and across-doppler-unit migration are analyzed,and some long-term accumulation algorithms which is effective are studied.Finally,detection point trace data is analyzed,and the traditional plots centroid algorithm is researched.2.The long-term accumulation algorithm based on Compensating Second PhaseModified Keystone Transform(CSP-MKT)and long-term accumulation algorithm based on Modified Keystone Transform-Autocorrelation(MKT-Autocorrelation)is proposed,which solve the problems of across-range-unit migration and across-dopplerunit migration in the case of long-term accumulation of signal energy.The performance of detecting the weak target is improved in the external transmitter system of high orbit satellite,and then some improvements are made to reduce computational complexity.Finally,the effectiveness of the two algorithms is verified by numerical simulation.3.The plots controid algorithm based on the Modified Density-Based Spatial Clustering of Applications with Noise(MDBSCAN)and the plots controid algorithm based on peak clustering are proposed,which solves the problem that multi-target point data with huge density differences and uneven distribution are difficult to perform effective ploting centroid.Among them,the plot centroid algorithm based on the MDBSCAN is better,compareed to the plot centroid algorithm based on boundary detection.The plots centroid algorithm based on peak clustering implement further improvements,which greatly improves the operation speed,which is more conducive to engineering realization.4.The signal processing flow required for the detection of weak targets under the external transmitter system of high orbit satellite is proposed,and then the simulation software of the external transmitter system of high orbit satellite is designed to verify the validity of the signal processing flow.