Research On Single Station Direct Position Determination Technology For Non-circular Signals

Real-time and accurate wireless signal positioning technology plays an important basic supporting role in commercial and military applications.Due to the rapid development of global satellite navigation,intelligent transportation system,battlefield target detection and tactical coordination,there is an urgent need for more accurate and rich radiation source positioning information,which puts forward higher requirements for wireless signal positioning technology.The direct position determination（DPD）technology,which directly calculates the target position parameters from the original signal data,has become one of the hot spots in the research of scholars at home and abroad.Relevant research shows that the positioning method has higher positioning accuracy and resolution,and the positioning performance can be further improved by using the waveform characteristic information of the signal（such as the non-circular signal elliptic covariance is not zero）.However,the current research on the direct position determination of non-circular signal targets is not in-depth and comprehensive,especially under the influence of array color noise,small sample points,array error,etc.,the positioning performance of the relevant algorithms is limited.Relying on a military scientific research project and a natural fund project,this paper conducts research on single-station direct positioning technology for non-circular signals in view of the above non-ideal factors,aiming to further improve the positioning performance of targets under harsh signal conditions.The main research work and innovation points of this paper are summarized as follows:1.A single-station direct position determination algorithm based on improved fourth-order accumulation for non-circular signals is proposed for the problem of limited localization accuracy of DPD method under array color noise conditions.Based on the special structural characteristics of symmetric arrays,a series of fourth-order cumulant matrices are skillfully constructed to solve the problems of insufficient array aperture expansion and data redundancy in common fourth-order cumulants.On the basis of the non-circular characteristics of the radiation source signal,the data model is extended by using the array reception data and conjugate data to improve the computational efficiency of the algorithm while enhancing the degrees of freedom and localization performance of the method,which is applicable to the complex environment where the number of radiation sources is larger than the number of array elements and the array reception noise is color noise.The simulation results verify that the proposed algorithm can achieve higher localization accuracy and lower resolution threshold with less computational effort than the traditional fourth-order accumulation-based DPD algorithm.2.To address the problem that the performance of the traditional subspace class direct position determination method deteriorates seriously or even fails under the conditions of small sample points and correlated signals,an off-grid sparse reconstruction-based single-station DPD algorithm for non-circular signals is proposed.Firstly,the received data are stitched based on Euler transform to expand the array aperture,then the grid is divided in the localization area,and the off-grid sparse representation model about the received data is obtained by using the first-order Taylor series expansion.A sparse reconstruction DPD algorithm based on the ₁l parametrization is designed and an alternating iteration approach is used to solve the joint optimization problem to obtain an estimate of the target radiation source location.In addition,the model is highly scalable and can be solved more efficiently in the second-order cone programming framework.The simulation results show that the proposed algorithm has better localization performance than the traditional on-grid class sparse reconstruction DPD algorithm.3.A self-calibration single-station algorithm for maximum non-circularity signals is proposed for direct position determination under the influence of array mutual coupling errors.The Toeplitz property of different array mutual coupling error coefficients and the non-circular nature of the radiation source signal are used to develop an extended rank reduction estimation model,achieving the"decoupled"estimation of the target position parameters and the array mutual coupling error parameters.In addition,the parameter discriminability conditions of the proposed algorithm are analyzed,and the Cramér-Rao bound for the joint estimation of the target position parameters and the array error parameters under the independent maximum noncircular rate signal model is derived,and the mean square error of localization under the influence of finite sampling is derived using matrix perturbation theory.The simulation results show that the proposed algorithm can locate the number of sources and the target localization accuracy are significantly improved compared with the traditional rank reduction estimation self-calibration algorithm,and the localization performance can approach the corresponding performance bound.