Research On Air High-speed Target Detection Technology Based On Opportunity Illuminator

In recent years,with the rapid development of wireless and radar technology,passive radar system,as a bistatic radar system which uses the third-party illuminator to detect target,has become a promising system complementary to the traditional radar system that need heavy transmission devices currently because of its low cost and strong concealment.However,due to the illuminator signal which is not specially designed for radar,the transmission power and other characteristics are not controlled,and it is very easy to be disturbed by noise or other factors.Improving the detection performance of the system is one of the key problems of this kind of radar system.Aiming at this key problem,this thesis studies on the target detection in the scene of spaceborne illumination source,air high-speed target and ground receiver,including the following points:1.The target detection method and signal processing flow of the passive radar system are studied,the characteristics of GPS signal and DVB-S signal as opportunity illuminator are analyzed,the geometric model and echo model are established for the scenes of spaceborne radiation source,air target and ground receiver.The problem of range and doppler migration under the model is studied and analyzed,which provides the theoretical model and other foundations for the follow-up work.2.The coherent accumulation method of high-speed target under the condition of opportunity illuminator is studied,and the first-order range migration correction methods such as Keystone Transform and Radon Fourier Transform are studied and simulated.Aiming at the first-order and second-order migration problems in the scene,the coherent accumulation method of TRT-DC-KT is proposed to complete the target migration correction and energy accumulation with low signal-to-noise ratio(SNR).At the same time,the Deramp-KT coherent accumulation method is studied to complete the energy accumulation with the complexity reduction.3.Aiming at the problem that the signal of the target with long-time observation cannot be regarded as coherent,the hybrid accumulation method based on KT-Fr FT is studied.Through the method of conherent and non-coherent hybrid accumulation,the long-time accumulation and target detection in the scene can be effectively completed.Aiming at the situation that the target has more complex motion,the hybrid processing method is extended to higher-order problems.A hybrid accumulation method based on KT-TMC is proposed,and the framing constraints under this method are constructed to effectively complete the hybrid accumulation of inter frame and intra frame signals,which not only compensates the high-order range and Doppler migration,but also completes the target detection under the condition of low SNR.The above research contents are verified by theoretical analysis and simulation experiments,which can effectively complete the detection of air high-speed target with opportunity illuminator.