Research On Three-dimensional Geomorphological Features Of Radar Emitter Signal Ambiguity Function

As the key link of electronic reconnaissance,radar emitter signal sorting is to separate the signals from the same emitter from the intercepted enemy radar emitter signal,so as to provide important information support for our own reasoning and decision-making of battlefield situation,threat level,activity law and tactical intention.In recent years,with the rapid development of complex radar system,radar emitter signals show the characteristics of diversification of modulation mode,complexity of waveform and fast change of parameters.It is difficult to meet the needs of current battlefield environment by using only five conventional parameters,namely,carrier frequency(RF),time of arrival(TOA),pulse width(PW),pulse amplitude(PA)and angle of arrival(DOA).Therefore,it is a feasible method to extract more efficient intrapulse feature parameters from a new perspective.As a classical time-frequency analysis tool,the ambiguity function can reflect the intrinsic information of the signal more completely,and can mine the effective features which are different from other signals.At present,the idea of feature extraction of ambiguity function is mainly oriented to single representative slices,such as main ridge slices of ambiguity function,diagonal slices and maximum near-zero slices.However,the single representative slice ignores a large number of members of the ambiguity function and has the limitation of low information utilization.Because the ambiguity function presents the similar mountain group geomorphology in space and the members of the higher elevation ambiguity function contain abundant intravenous information,this paper further excavates the threedimensional characteristics of the ambiguity function from the perspective of topography and landform,and achieves the following research results:(1)From the main and lateral perspectives,the ambiguity function is divided into "ridge" and "peak" landforms.After sliding average processing of the two landforms,the center of gravity of the main hill and the distribution radius of the main peak are extracted to describe the characteristics of the ambiguity function in the direction of time delay and frequency shift.(2)In order to solve the problem that time-delay and frequency-shift information can not be taken into account in the main side view,the Gaussian mask is used to smooth the ambiguity function and draw the contour of the ambiguity function as a further feature extraction object.Then the positive external moments and direction angles are extracted from the image processing angle to represent the distribution range and overall direction of the ambiguity function.(3)Based on noise robustness and computational complexity,the evaluation index and hierarchical model of radar emitter signal sorting characteristics are designed,and the weight of the index is determined by the method of simplified analytic hierarchy process.The main side view feature and contour feature of the ambiguity function presented in this paper are evaluated and compared with the main ridge section feature of the classical ambiguity function.The results show that compared with the main ridge section feature of the classical ambiguity function,the comprehensive performance of the main side view feature of the ambiguity function is improved by 4.12%,and the comprehensive performance of the contour feature of the ambiguity function is improved by 7.23%.It is shown that the features mentioned in this paper can better reflect the intra-pulse differences between signals,and have a strong timeliness,which can be used as an effective complement to the current radar emitter signal sorting feature parameter set.