Study On Synchronous Multi-target Jamming Technology Based On Digital Beamforming

Facing the increasingly complex radar countermeasure environment,it is very important that jammer can transmit different jamming signals simultaneously to multiple threat sources in the actual combat environment.This will also be an important development direction of future electronic warfare.Because of digital beamforming technology can quickly change the beam shape and direction,control precision and flexible,can be implemented quickly switch between multiple interference signal,through space power synthesis can achieve high power output,and has the advantages of the multi-beam forming ability at the same time,Therefore,in the field of electronic countermeasures,digital beamforming technology is a key technology to improve the performance of electronic jamming.In this paper,multi-target jamming technology based on digital beamforming is studied and the following work is carried out.1.Far field emission in uniform linear array model and narrowband signal model are studied,and analyses the narrowband emission on the technology of single beam forming and multibeam forming in principle,model and the relationship between the two.2.Based on the research of narrow-band multi-beam forming transmission technology,in this paper,the technology of wideband transmission digital multi-beam forming is studied by dividing the wideband signal into sub-band to process in frequency domain.The principle and model of wideband signal model and wideband transmission single beam forming and multi-beam forming technology are included.The method is simple in engineering implementation.3.Because resource consumption is too great by dividing the wideband signal into sub-band to process,so the wideband digital beamforming based on fractional delay filter in time domain is studied.The principle of the wideband digital beamforming technology based on fractional delay filter and the principle of fractional time delay and the influence of fractional delay precision on the system are analyzed.Then the design method of three fractional delay filters is introduced?Ideal structure plus window method(Hamming window,Chebyshev window),equiripple method and Farrow structure are included.The feasibility of the broadband digital beamforming method based on fractional delay filter is analyzed and a series of problems are still to be solved.4.At present,there are some difficult problems of wideband digital beamforming based on fractional delay filter in engineering implementation.The optimal design method of wideband digital beamforming based on second-order cone programming(SOCP)in frequency domain is studied.The amplitude and phase modulation of the wideband interference signal with a corresponding wideband FIR filter are used in each channel.Firstly,the principle and model of wideband transmission digital beamforming based on FIR filter are analyzed.In order to obtain the optimal filter coefficient,the linear constrained minimum power criterion(LCMP)is adopted to design and optimize the beamforming device.The effective utilization ratio of interference power is improved by reducing the interference power to the side lobe.By eliminating the frequency dependence of the side lobe constraint and transforming the analytical form of the filter coefficient solution into the corresponding second-order cone programming(SOCP)form,the optimization difficulty reduced.