Research On DOA Estimation Algorithm Of Distributed Multi-Shipborne Based On Virtual Array

Distributed multi-shipborne radar(DMSR)is a new system radar that places the radar on different ships.This kind of radar can flexibly configure system resources according to actual needs and perform joint coherent processing on the received data of different shipborne radars,so it has both flexible maneuverability and high angle resolution.Compared with other radar systems,DMSR has higher signal processing complexity and more technical difficulties.Joint coherent processing of data from different shipboard platforms is a technical difficulty that needs to be solved.Therefore,the main content of this paper is to achieve array and signal reconstruction of distributed arrays under the conditions of coherence,and finally to achieve highprecision angle estimation of distributed systems.This paper analyzes the spatial and signal model of the DMSR system,introduces the related theory of DOA estimation,including the MUSIC algorithm,decoherence algorithm and beamforming method,which provides the theoretical basis for signal reconstruction for DMSR.The complex positional relationship of the ships in the DMSR system determines that the overall configuration of the system is also complicated.In this case,the system cannot directly realize effective signal reconstruction.Therefore,in order to realize the signal reconstruction of the DMSR system,it is necessary to perform array reconstruction on the system first.The virtual array mapping method based on array interpolation is a common array reconstruction method.This method can change the array structure to meet the uniformity requirements.In this paper,the method is simulated and analyzed,and the signal-to-noise ratio attenuation and noise coloration in the virtual transformation process are explained,and the concept of array structure difference is proposed.Then the effects of common factors such as interpolation interval,angular interval,number of virtual array elements,and distance between subarrays on the performance of virtual mapping are discussed.When the configuration of the distributed array is time-varying,the time-invariant processing method is introduced,and the principle of setting the virtual array structure by the midpoint method and the segmentation method is studied.The performance of the two methods is compared.A data compensation method is proposed based on the time-varying relationship of the steering vector,and compared with the segmentation method.After that,the method of pre-estimation is introduced,the principles and methods of virtual array setting are summarized,and combined with actual distributed systems and common DOA algorithms,the simulation results show that the DOA estimation of distributed systems based on virtual mapping can achieve good results.During array reconstruction,excessive differences in the number of array elements before and after the virtual map will cause the performance of the virtual map to degrade.In order to solve this problem,based on the idea of synthetic aperture,this paper uses the synthetic aperture method to increase the number of array elements before virtual transformation,thereby reducing the difference between the number of array elements before and after transformation,and studied the overlapping correlation method and non-overlapping correlation method.The principle is introduced and the steps are summarized.The simulation results show that the effect of improving the DOA by synthesizing the virtual aperture and then performing the virtual transformation is obvious.In the actual DMSR system,the baseline distance between ships may be long,and the DOA estimate will have ambiguity problems at this time.This paper analyzes the ambiguous characteristics of distributed arrays,introduces the principle of the dual-scale ESPRIT algorithm,and considers the case where the subarrays are sparsely distributed and there are multiple baselines.In this paper,the use of the dual-scale ESPRIT algorithm in the above situations is studied,and the relevant algorithm steps are summarized.Simulation results prove the effectiveness of the algorithm.Through disambiguation of DOA estimation,the high-precision and unambiguous DOA estimation of the distributed system is finally achieved.