Low Complexity Group Target Sorties Determination Method For Close Formation Scenarios

To increase combat intensity and strike intensity,multi-aircraft formation has been widely used in modern air attack.The air surveillance radar’s ability to distinguish group target sorties is of great significance to analyze the air situation accurately and establish the correct combat plan.However,most air surveillance radars equipped at present in many countries around the world are narrowband radars with low range resolution,which is difficult to distinguish group target sorties in close formation.In addition,when existing digital array radars based group target sorties determination methods are used for engineering realization,a new system radar or a big change in the current radar’s technical conditions is usually required,leading to high cost.To overcome the problems mentioned above,by fully utilizing the features of the active air surveillance radars that usually has the frequency agility ability,from the perspective of joint pulse synthesis and monopulse estimation,this paper proposes a low complexity group target sorties determination method based on chirp-subpulse steppedfrequency signal.The main contributions of this paper are as follows:Aiming at the problems of high computational complexity and low bandwidth synthesis operation efficiency in existing pulse synthesis algorithms for chirp-subpulse stepped-frequency signal,a low-complexity frequency-domain synthesis algorithm is proposed to obtain high resolution range profile.Firstly,after analyzing the reasons for the high complexity of classical frequency-domain synthesis algorithm and the existing fast frequency-domain synthesis algorithm,we optimize the algorithm flow by segmented upsampling in frequency domain and superposing frequency spectrum cyclically.Then,we analyze the computational complexity of the proposed algorithm,the classical frequency-domain synthesis algorithm,and the existing fast frequency-domain synthesis algorithm.Simulation results show that the proposed algorithm greatly reduces the complexity without degradation of performance,and when the number of subpulses is 32,the complexity of proposed algorithm is reduced by an order of magnitude compared to the classical algorithm and by 28.05% compared to the existing fast algorithm.The proposed low-complexity frequency-domain synthesis algorithm establishes the basis for the research on group target sorties determination in close formation scenarios.Based on the research above,to track the problem of high complexity and high implementation cost of the existing group target sorties determination method in close formation scenarios,a joint pulse synthesis and monopulse estimation based group target sorties determination method is proposed.We first analyze the source of the range image distortion caused by target motion,construct a velocity compensation factor to eliminate range image distortion,and obtain the clear high resolution range profile.On this basis,the azimuth angle and pitch angle of every scattering point can be solved by monopulse estimation technology,and then the scattering points can be distinguished using distance and angle information.Then,the hierarchical clustering algorithm is used to distinguish the group target sorties.Finally,the simulations are conducted using group target echo based on the spatial distribution characteristics of scattering points.The results show that when the distance between two sorties is greater than 24 meters,the resolvable probability can reach more than 90%.The research results in this paper can provide strong support to the improvement of the active air surveillance radar or the engineering realization of the newly developed conventional system air surveillance radar.