Research On Array Anti-Jamming Technology Of Airborne Weapon Datalink

Airborne weapon datalink(AWD)is a dedicated datalink for information transmission of airborne weapon targets and cooperative control.AWD is the key for boosting the strike capacity to time-sensitive targets by airborne weapons and gaining the tactical advantages in information age war system-of-systems counterwork.The working process of the AMD is a process that the weapon is moving away from its own platform and reaching the enemy platform.The conventional anti-jamming measures will fail easily when facing the new generation of jamming platforms with microsecond-level signal capturing time and megawatt-level interference equivalent radiation power.The array anti-jamming technique exploits the antenna array,which is in a certain arrangement spatially,to receive and process signals,and can make the high-gain main lobe point to the desired direction,enhance the useful signal,form null steering in the jamming direction,restrain interference and noise.When the array anti-jamming technique is applied to the AWD,the anti-jamming capacity of the AWD will be significantly improved.Due to the characteristics of environment,in the AWD system,the array anti-jamming technique needs to estimate the direction of arrival(DOA)of the signals.Specially,it raises some other questions,e.g.,the DOA estimation of the non-circular signals of the guidance datalink,the robust adaptive beamforming with high dynamic and simplified algorithms which can be suitable for the airborne with limited computation ability.This dissertation makes an intensive study of the problem and the main content and innovations are listed as following:1)For the DOA estimation of non-circular signals with a non-uniform linear array,the conventional estimation algorithms costs high complexity due to the two-dimensional(2D)search of DOAs and non-circular phases.In this dissertation,three reduced-dimension(NC)algorithms are proposed,including NC-Capon,NC-MUSIC,NC-PM.The proposed algorithms can extend the array aperture with the aid of the non-circular characteristic and exhibits better estimation performance than the conventional algorithms.Meanwhile,the proposed algorithms need one-dimensional(1D)search only and have low complexity.The cramer-rao bound for DOA estimation problem with non-uniform linear array is also derived,which provides a good tool for theoretical analysis of the algorithm performance.Additionally,a generalized ESPRIT(GESPRIT)-based algorithm for DOA estimation of non-circular signals with a non-uniform linear array,called NC-GESPRIT,is also proposed.The proposed NC-GESPRIT algorithm includes two types,the first one exploits 1D spectrum search and the other one exploits polynomial rooting.The NC-GESPRIT can estimate DOAs without prior knowledge of non-circular phase information and outperforms the traditional GESPRIT.2)For the 2D DOA estimation problem with a non-uniform L-shaped array,the successive MUSIC(S-MUSIC),successive Capon(S-Capon),successive PM(S-PM)algorithms are proposed,which replace the 2D search in conventional algorithms with two successive 1D searches.The complexity of the proposed algorithms is greatly reduced,while the performance is close to the 2D search algorithms.The proposed algorithms can achieve automatically pairing of 2D DOAs.3)For 2D non-circular DOA estimation with two-parallel linear array,the corresponding NC-ESPRIT and NC-PM algorithms are proposed,which fully exploit the non-circular characteristic of the signals and outperform traditional ESPRIT and PM algorithms,respectively.A NC-PARAFAC algorithm for 2D DOA estimation of non-circular signals with two-parallel linear array is also proposed.This algorithm uses the non-circularity of the signals to extend the PARAFAC model and estimates DOAs through the trilinear decomposition method without additional pairing.The NC-PARAFAC algorithm outperforms ESPRIT,PM,PARAFAC,NC-ESPRIT and NC-PM.4)The generalized eigenspace-based robust adaptive beamforming problem is also investigated.In the AWD,due to the high power of the desired signal,high dynamic of the airborne weapon platform and the array error in engineering development,some problem exist,e.g.,the pointing error of the expected signal and the null steering,the high side lobe.To cope with these problems,we introduce the amplitude weighting technique to the expected signal and interference subspace and propose a novel eigenspace-based robust LCMV adaptive beamforming method.Then we consider the null-widening technique in the propose LCMV method,investigate the eigen-decomposition of the covariance matrix of the tapered signals,and propose a robust beamforming algorithm with wide null steering.The proposed algorithm has good robustness,fast convergence speed and low side lobe.