Adaptive Detection Method Based On ABF Of Subarray

The research to the technology of array signal processing has experienced morethan40years, it puts forward a lot of mature theories and effective methods.Adaptive beamforming technology played a huge role as an important aspect ofarray processing. Modern phased array radar has always hundreds of array element,the structure of subarray become a way of effective in the signal processing,therefore the research of the adaptive beamforming method has an importantsignificance in subarray.It often use the structure of plane array to dispose array element in the actualarray antenna design, so signal model of two dimension is constructed in thesubarray. It can suppress strong interference very well in the case of enoughsnapshot data in the method of sampling covariance matrix inversion (SMI) with afaster convergence speed, but the cost is that the sidelobe level of adaptive pattern ishigher than quiescent pattern. If the snapshot data is insufficient, the mainlobe ofadaptive pattern will produce distortion, the sidelobe is higher and ripple. Thereforethe diagonal loading factor is introduced to revise, it can inhibit the eigenvaluespread out and get a good pattern.In the premise of restraining the interference, it hopes to get the sidelobe ofpattern as low as possible, subspace projection and penalty function method canachieve the above requirements respectively. In The subspace projection method canrestrain it and have a lower sidelobe with interference, consistent with quiescentpattern without interference. Penalty function method suppress the jitter of sidelobewith constraints and loading factor. Combining with the characteristics of the abovetwo methods, it realized the constraint adaptive beam synthesis (CAPS) method, itcan restrain the interference in adequately and get ideal low sidelobe level at thesame time, and saves the process of selecting the load values.Adaptive beamforming is applied to adaptive detection in subarray, it make theadvantage of array processing technology. Generalized likelihood ratio test (GLRT)and adaptive matched filter (AMF) are two good performance detectors, theprobability density of the test statistics is not dependent on the noise, so it can havea constant false alarm rate. Under the condition of setting probability of false alarm,detection threshold is obtained, and then compared with the detection statistics anddetection threshold, test results are obtained.Three types of adaptive beamforming algorithm is combined with two kinds ofdetector, respectively it is given detection performance curve of different beamforming method along with the change of SNR under the same kind of detector,and the detection performance curve of different detector along with the change ofSNR under the same kind of beamforming method, so as to judge the merits of thedetection performance, and verify the probability of false alarm and the relationshipof the detection probability and the probability of false alarm is obtained.