| Low elevation target height measurement requires selecting a suitable height measurement model.Based on this model,a suitable low elevation height measurement algorithm is used to estimate the direction of arrival of the low elevation target,and then the geometric relationship in the model is used to calculate the height of the low elevation target.Contemporary radar will be intimidated by anti radar technology,and VHF radar has been widely studied due to its characteristics of anti radiation missiles and anti stealth.In the process of estimating low elevation angles of targets using VHF radar,multipath effects can affect the accuracy of height measurement algorithms.Therefore,further research is needed on the performance of low elevation height measurement algorithms.Complex positions can cause varying degrees of distortion in the amplitude and phase of multipath echoes during the reflection process,and the reflection phenomenon of multipath echoes in complex positions does not match the reflection phenomenon involved in classical multipath models.This article solves the mismatch problem by perturbing the multipath model,and proposes a Synthesized Vector Maximum Likelihood(SVML)algorithm based on the perturbed multipath model,and analyzes the performance of the algorithm.The main content is summarized as follows:1.Study the height measurement model.Firstly,introduce the received signal under the received signal model;Then introduce the classic multipath model and the principle of obtaining unknown parameters within it;Secondly,a spherical model suitable for angle estimation of far-field targets is introduced;Finally,the disturbance multipath model is introduced,which uses disturbance parameters to reflect the degree of disturbance caused by multipath echoes passing through the battlefield.2.Analyze various classic low elevation altimetry algorithms.This article mainly introduces the Digital Beamforming(DBF)algorithm,Multiple Signal Classification(MUSIC)algorithm,Spatial Smoothing MUSIC algorithm,Maximum Likelihood Alternating Projection(ML-AP)algorithm,and linear prediction algorithm for spatial spectrum estimation,and analyzes the characteristics of each algorithm.3.Research on height measurement algorithms for complex arrays underground.In the complex array underground,the disturbance multipath model is used to reflect the degree of disturbance caused by the position to the multipath echo using disturbance parameters.Firstly,we introduce the perturbed multipath(PSBL)algorithm based on sparse Bayesian learning.Simulation results show that this algorithm can accurately estimate disturbance parameters;Then introduce the SVML algorithm;Finally,the disturbance parameters estimated by the PSBL algorithm are introduced into the SVML algorithm,and the SVML algorithm based on the disturbance multipath model is studied.The parameter estimation performance of this algorithm is analyzed using computer and measured data.4.Compare the parameter estimation performance of multiple algorithms and perform height measurement processing on the measured data of a certain radar.Firstly,the performance of various algorithms is compared,and then the performance of several low elevation height measurement algorithms for VHF radar is studied using measured data.The impact of moving target indicator(MTI)on target parameter estimation is analyzed.Through comparative analysis of multiple algorithms and the processing results of several height measurement algorithms on measured data,it can be concluded that the performance of the Maximum Likelihood(ML)algorithm is superior to the spatial smoothing MUSIC algorithm and the fourth order linear prediction algorithm.The estimation performance of SVML algorithm is superior to DBF algorithm and ML-AP algorithm.The lobe splitting method and SVML algorithm both have high performance in angle estimation of low elevation targets. |
