Detection Of Turbulence By Airborne Radar Under Low Signal To Noise Ratio

Atmospheric turbulence is a kind of dangerous weather target that is often encountered in the course of carrying out the mission.The spectral width of the echo signal is used as the standard to measure the turbulence intensity in the detection of atmospheric turbulence.However,for the atmospheric turbulence with low signal to noise ratio(SNR),it is impossible to detect the early warning.In order to solve the above problems,this paper presents two methods for the estimation of turbulence spectral width,which can obtain better estimation results at low SNR and improve the detection probability.Firstly,the characteristics of atmospheric turbulent flow field are introduced,and several commonly used methods of atmospheric turbulent wind field and its application background are introduced,and the Von Karman turbulence model is chosen to simulate.Secondly,the airborne phased array weather radar echo receiving model is studied,the atmospheric turbulence model is established and the echo echo signal is simulated,and the turbulent wind field detection of several common methods were introduced and analyzed.Thirdly,a method based on covariance matrix fitting is proposed to estimate the spectral width of atmospheric turbulence.In line with the spectrum of target echo Gauss spectrum based turbulence on the characteristics of the turbulent structure target parametric covariance matrix model;and then use the characteristic of the echo signal subspace orthogonal to the parametric model of echo estimation of the covariance matrix of covariance matrix and turbulence target fitting,by solving the cost function to estimate the turbulence spectrum.In this method,the accurate estimation of the spectral width can be obtained when the SNR is low.Finally,this paper puts forward a kind of complex based on compressed sensing low degree of atmospheric turbulence spectrum estimation method,this method is based on the atmospheric echoes the space-time characteristics of the establishment of the wind velocity spectrum in redundant space-time dictionary wide;and then use the compressed sensing principle to achieve the reconstruction of echo signal.The proposed method can obtain more accurate spectral width estimation at low SNR,and it can reduce the computational complexity in the case of limited performance.