Detection Of Low-altitude Wind Shear With Amplitude And Phase Errors

Low-altitude wind shear usually occurs below an altitude of 600 meters.When airborne weather radar is used to detect low-altitude wind shear,the aircraft is closer to the ground at this time,so the echo signal received by the weather radar contains a lot of ground clutter signal,the low-altitude wind shear cannot be detected directly.In order to complete the low-altitude wind shear detection under the background of clutter,we must first suppress the ground clutter.In practical applications of airborne meteorological radars,when there is an amplitude and phase error of the array elements,the degree of freedom of clutter is increased,and the clutter is scattered on a two-dimensional space-time plane,occupying a larger two-dimensional space,making the clutter spectrum more complicated,so that it affects the clutter suppression effect,which leads to inaccurate detection results of low-altitude wind shear.Based on this,this paper studies the low-altitude wind shear detection method based on the amplitude and phase errors.Firstly,the paper studies the echo data model of airborne meteorological radar ground clutter and low-altitude wind shear under amplitude and phase errors.Based on the echo data model,the airborne weather radar echo signals with amplitude and phase errors are simulated.The distance dependence of ground clutter on airborne weather radar is derived.Finally,the space-time two-dimensional spectrum of low-altitude wind shear and ground clutter with and without different errors are simulated and analyzed.The next low-altitude wind shear detection laid the foundation.Secondly,in order to solve the problem of inaccurate detection of low-altitude wind shear in the presence of amplitude and phase errors,a low-altitude wind-cut detection method based on combined space-time main channel-local joint space-time adaptive processing is proposed.This method first corrects the distance dependence of clutter based on radar echo data;then constructs an adaptive processor for reduced-dimensional transformation according to the algorithm principle;finally,uses the obtained optimal weight vector to adaptively adapt the radar echo data Filter to complete low-altitude wind shear wind speed estimation in the case of amplitude and phase errors,so as to realize low-altitude wind shear detection.Simulation results show that the method can well achieve low-altitude wind shear detection under the condition of amplitude and phase errors.Finally,in order to solve the problem of high complexity and high calculation amount ofCMCAP-JDL method,an improved auxiliary channel low-altitude wind shear detection method with a small amount of calculation is proposed.This method first adopts the clutter distance-dependent correction method based on the modified steering vector under the amplitude and phase errors;then analyzes the clutter energy distribution of the unit to be measured in the beam-Doppler domain,and selects the auxiliary according to the clutter energy distribution characteristics Channel to build an adaptive dimensionality reduction processor;finally,the optimal weight vector of the solved adaptive dimensionality reduction processor is used to implement adaptive filtering of radar echo data to complete the accuracy of low-altitude wind shear wind speed in the case of amplitude and phase errors Estimation to achieve wind shear detection.The simulation results show that the method can well realize low-altitude wind shear detection when there is amplitude and phase error,and further reduce the amount of calculation and algorithm complexity.