Target Threat Evaluation And Jamming Effect Evaluation In Complex Low Altitude Environment

Target threat assessment is a prerequisite for decision makers to develop a scientific target jamming strategies.Target jamming effectiveness assessment can constrain the management of jamming resources to improve their utilization efficiency.Both are important components of target situation assessment.Both of the above are important components of target situation assessment.With the proliferation of low-altitude targets represented by civilian UAVs,the accompanying low-altitude detection and defence systems are becoming more complex and have a wider variety of detection sensors.It is therefore of great importance to extract useful information from the huge amount of complex data acquired by multiple heterogeneous sensors and to quickly and effectively assess the threat level and interference level of the target.Existing assessment methods generally suffer from one-sided metrics and lack of online assessment cognitivisation.To address this,this thesis focuses on the online assessment of dynamic threat and jamming effects of low-altitude targets,and conducts an in-depth study as follows:(1)To address the problem of difficult access to dynamic target data in low-altitude defence,a simulation and data extraction scheme for low-altitude defence target scenarios based on the STK(Satellite Tool Kit)simulation environment is proposed.Firstly,several common flight states and movement characteristics of the main research target are initially analysed as the basis for establishing a low altitude target movement model.Using the STK development environment,explore the establishment of a simulated confrontation scenario between a low-altitude defence system and a threat target,set the target position parameters at different moments,simulate the flight state of the target in the confrontation,and pre-process the collected flight state trajectory information to provide data support for the subsequent target threat assessment and online evaluation algorithm of jamming effects.(2)To address the characteristics of redundant and inefficient target threat assessment indicators and time-varying target information in the low-altitude countermeasures environment,a dynamic target threat assessment method based on TOPSIS(Technique for Order Preference by Similarity to Ideal Solution)and grey correlation degree is proposed.Firstly,considering that the target’s electromagnetic information parameters are an effective assessment basis in the threat assessment of low-altitude targets,the dynamic electromagnetic parameters of the target are introduced into the assessment index system to build a multi-source heterogeneous sensor assessment index system;Secondly,game theory is introduced to solve the subjective/objective weight values of the assessment indexes separately,and a linear proportional coefficient game model is established to obtain the index weights after the optimal combination of weighting.Finally,the normal cumulative distribution method is used to solve the time series weights and solve the problem of dynamic target information and weight allocation,thus obtaining the target dynamic weighted decision matrix.The simulation results show that the threat assessment results of dynamic targets obtained by the above proposed method are more objective and reliable than other traditional methods.(3)To address the problem of online jamming effect assessment in complex countermeasures environment due to time-varying target states,a hybrid DE-SVM(Differential Evolution-Support Vector Machine)based online jamming effect assessment method is proposed.Firstly,the online jamming effectiveness evaluation model is established by extracting the flight state quantities,target motion characteristics and target antijamming indicators that are related to the online jamming effectiveness of low-altitude targets.Secondly,considering that the target flight state quantity is a factor in assessing the interference effect of a target,a flight state recognition model based on support vector machines is established.Combining the idea of motion decomposition to segment its trajectory,and then recognise the segmented flight movements from the vertical and horizontal axes respectively,thus enhancing the effectiveness of recognition.Finally,the flight state sample data is constructed based on STK simulation software,and the recognition model is trained to achieve online interference effect evaluation of low-altitude targets,and is validated by experiments.The simulation results show that the recognition method has high accuracy and realtime performance.