Research On Technologies Of Jamming Effect Evaluation Against Multifunction Radar

Jamming effect evaluation,which evaluates combat capability of a jammer,is a quantitative and qualitative method to measure how strongly the target radar is interfered.As the target of the jamming side,multifunctional radars of new systems have agile waveforms,for which jamming radars is not only more difficult,but jamming effect evaluation methods also need be improved.The jamming effect evaluation indices and methods against traditional radars hardly match the features of multifunctional radars.Therefore,more researches on jamming effect evaluation adapted to multifunctional radars is very meaningful.Jamming effect evaluation against multifunctional radars at the present stage mostly focuses on self-screening jamming.This thesis proposes a new index,the tracking density,for online jamming effect evaluation from the perspective of stand-off jamming.This index expresses the frequency of the occurrence of the tracking modes of a multifunctional radar within a tracking update period,and larger tracking density means that the corresponding radar tracked more targets and tracked more frequently,for which this radar had more threats to the jamming side overall.So,the jamming side can evaluate the present suppress jamming effect against a multifunctional radar by analyzing the change of the tracking density before and after the jamming is put into effect.However,estimating tracking density requires that the jamming side has the ability of estimating the number of tracking modes within a series of radar modes.As a result,this thesis proposes to accurately estimate this index based on amplitude and waveform arrays of radar waveform units via multi-column convolutional neural network(MCNN).For simulating to validate the accuracy of the estimation of tracking density,this thesis researches the hierarchical structure model of “function/ mode/ waveform unit” of multifunctional radars from the perspective of the reconnaissance side,demonstrates the rationality to extract waveform units based on pulse amplitudes,and proposes a modified agglomerative hierarchical clustering algorithm named AHCME,based on which waveform units from multifunctional radar are extracted exactly.Additionally,the technique for order preference by similarity to an ideal solution(TOPSIS)is utilized to synthesize the tracking density and several typical indices of jamming effect evaluation,based on which the overall jamming effects can be evaluated synthetically.The main research work of this thesis is as follows:In Chapter 2,a hierarchical structure model of “function/state/waveform unit” of multifunctional radars is established,and the interconnections among the levels are analyzed so that the complexity of analyzing multifunctional radar signals is reduced.Afterwards,a modified agglomerative hierarchical clustering algorithm named AHCME is proposed by introducing a factor that measures the degree of inter-cluster mutual exclusion.Without any prior information,the AHCME algorithm is used to extract the waveform unit in a series of radar pulses only based on the information of pulse amplitudes.It is hold that the average accuracy rate of estimating the change points of the simulation data’s waveform units is more than 95% when the noise power is less than-66 d Bm W.In Chapter 3,several common criteria and the corresponding indices for jamming effect evaluation are analyzed and summarized,and the definition,significance and estimating principle of the tracking density index of multifunctional radars are elaborated.Under the premise that waveform units are extracted ideally,the array of waveform units with twodimensional parameters,waveforms and amplitudes,is defined,based on which the tracking density of the multifunctional radar are evaluated accurately via a MCNN that can analyze the multi-scale information.It is hold that the accuracy of the simulation data’s tracking data rate estimation reaches 90% and more with the tolerance equal to 1.Chapter 4 analyses how tracking density and several typical indices change before and after the radar is jammed by standoff jammers and how they are related with jamming effects.At the same time,a multi-index synthetical evaluation method,TOPSIS,is researched,which is taken as an example to do the online multi-index synthetical evaluation against multifunctional radars based on the above-mentioned indices by calculating the simulation data’s distances between the reconnoitering results of all indices and positive and negative ideal solutions after jamming respectively as evaluation results and comparing them.