Moving Target Detection For Missile-borne Radar Under Complex Environment

When the missile-borne radar is in the forward-looking array downlooking working state,there will have strong ground-sea clutter and interference signals with complex spectral characteristics,which will reduce the precision guidance ability of the missile-borne radar and seriously affect the target detection performance of the radar.Therefore,in order to improve the combat capability of the missile-borne radar,it is necessary to analyze the characteristics of clutter and jamming signals that may be received by the radar during its operation,and carry out the clutter and jamming suppression.With the improving of the against and reverse against electronic technology,the transmitted signals will be intercepted by jammer,and the transmitted signals will be remodulated to generate the deception jamming signal inside the jammer to interrupt the received terminal.For fixed frequency signal radar,the deception jamming signal will lead to the loss of the real goals,however,this problem can be avoided in the frequency agility radar.The technology of frequency agility is the main method to suppress the narrow-band interference,and it can plus the range resolution in the meantime.Therefore,this article carries out the echo signal model of missile-borne frequency agility radar and discuss the data processing method of this model.Firstly,the characteristic of the received signals will be analyzed,which including the target,clutter and interference signals,and then an effective method to suppress clutter and interference signals is proposed.Then,based on maximum likelihood function,a computationally efficient algorithm for estimating target parameters of FAR under jamming environment is developed.Ultimately,the whole process of echo signal is completed.The main work of this paper is summarized as follows:1.According to the actual working status of the missile-borne radar,the geometric model of the radar observation in the downward-looking state of the missile-borne forward-looking array radar is established,and the echo signal in the non-stop mode is derived on the basis of the frequency agile radar.Then we discuss the spatial-temporal characteristics of clutter in subduction motion under the visual state of the missile-borne frequency agile forward-looking array radar,which including the distance dependence of clutter,clutter distance blur and velocity blur.The experimental results verify the correctness of the inference.2.Due to frequency agility,the same speed target will produce different instantaneous Doppler frequencies under different carrier frequencies.Therefore,it is not possible to directly perform Fourier transform on the pulse domain signal to achieve energy accumulation.Based on the discrete Fourier transform method,we converted the echo data to the range-velocity plane,then the filtering method of clutter suppression in the velocity channel is discussed.3.Then we analyze the ability of frequency agile signal to suppress deceptive interference and the effect on the effective accumulation of target energy,and an effective method for target accumulation of frequency agile radar is proposed.Firstly,for correcting the distance walk,a coupling between the fast time and slow time domains is removed through Keystone transformation.Based on this operation,we carry out the Doppler compensation and velocity compensation for the echo signal to realize an effective accumulation of target energy.The simulation experiment proves the effectiveness of the method of distance walk correction and phase compensation.4.After the target energy is effectively accumulated,a fast estimation algorithm of target parameters based on the maximum likelihood function is proposed.The analytical solution of the target estimation is obtained by the low-order approximation of the multi-dimensional maximum likelihood function,while avoiding the huge amount of calculation caused by the fine grid search method,the performance of target parameter estimation is guaranteed.On this basis,according to the target point track information,the probabilistic data interconnection algorithm is used to track the target signal to realize the track prediction.