Research On Low-elevation Estimation Based On Coprime Array In Passive Radar

The low elevation angle estimation problem has always been an important research topic for external radiation source radar target positioning and tracking.The target and multipath signals are regarded as a pair of closely related point sources in the low elevation angle model.To achieve the target elevation angle Accurate estimation is actually a problem of super-resolution of two spatially adjacent coherent sources.Therefore,how to improve the angular resolution of the array antenna is the key to improve the estimation performance of the low elevation angle of the external radiation source radar.In view of the above problems,this paper aims at improving the angle resolution.Based on the previous work,starting from the low-elevation mirror image signal model,the low-elevation angle estimation algorithm of the coprime array is studied.The main research work and contributions of this article are summarized as follows:1.Study the model and method of low elevation angle estimation of external radiation source radar.The multipath echo signal is regarded as a coherent signal source close to the target direct wave signal position,and the array received signal model is constructed by the geometric relationship between the radar,the target,and the reflective surface.Then,two commonly used low-elevation target DOA(direction-of-arrival,DOA)estimation techniques are studied: spatial smoothing super-resolution algorithm and DOA estimation method based on compressed sensing.Finally,the experimental simulation results compare the two algorithms.Resolution performance,elaborated on their respective advantages and disadvantages.2.The arrangement of the coprime array structure and the DOA estimation method of the coprime array based on incoherent signals are studied.Firstly,the array structures of simple coprime arrays and extended coprime arrays and their advantages in array freedom and aperture are analyzed.Then combined with the structural characteristics of coprime arrays,two DOAs based on incoherent received signals are studied The estimation methods are the co-prime array DOA estimation method based on virtual array and the co-prime array DOA estimation method based on compressed sensing.Finally,the two algorithms are simulated and compared with the estimated performance of the traditional uniform linear array.3.Developed a low elevation angle estimation method for co-prime arrays for coherent signals.Firstly,in the low-elevation mirror model,the form of the virtual uniform linear array received signal based on the coherent signal is deduced.The effect of the coherent signal is demonstrated through computer simulation,and then the virtual array method in the low-elevation mirror model is clarified.Approximate feasibility,and finally verified its advantages through simulation experiments,and realized high-resolution angle estimation.