Detection Of Low-altitude Windshear Based On Rank-Reduced STAP

Airplanes get forward weather information by airborne weather radar.The phased-array mode will introduce to airborne weather radar to handle weather information in the future,its ability of ground clutter suppression will get stronger,which makes low altitude wind-shear detection more precisely.Space Time Adaptive Processing(STAP)is an effective method to suppress clutter in phased array radar.But STAP will be failing to estimate parameter of target with insufficient training samples to estimate covariance matrix of clutter accurately.For there are many nonideal factors in the practical environment,it decrease the Independent Identical Distribution(IID)samples,so it affects the performance of STAP seriously.Reduced-Rank STAP technology can reduce adjustable weight of the system,which can decrease the demand of the training samples to estimate covariance matrix of clutter in STAP method.So it is important to research on introducing Reduced-Rank STAP into detection of low altitude wind-shear to improve the performance of the airborne weather radar.First of all,starts with the data mode of airborne forward phased-array weather radar,the simulation approach of the wind-shear field echo and background clutter are introduced.Then the affection on parameter estimation by clutter range dependence and heterogeneous clutter in look-forward mode are analyzed.Secondly,when the radar works in looking-forward mode for low altitude wind-shear detection,the samples is not enough that makes the estimate performance get worse.So a detection method of wind speed estimation based on improved Eigecanceler-Capon(EC-Capon)is proposed.This method can estimates clutter subspace with eigende-composition accurately,then use the orthocomplement space of clutter subspace replace sampling matrix inversion(SMI)to get weight vector.Finally the wind speed estimation will get according to the Capon rule.Thirdly,when the number of training samples is none,a new method of wind speed estimation based on Multistage Wiener Filter(MWF)is proposed.It introduced the modeling of the space and time steering vector of the wind-shear field,we can process the data of unit under test by rank-reduced adaptive filter directly without the clutter covariance matrix estimation of the detective unit,then get the clutter suppression and estimate wind speed.