Research On Direct Position Determination Of Multiple Emitters For Distributed Radar Systems

Emitter localization in distributed radar systems,for that the widely distributed radar stations directly intercept the transmitted signal of the emitter and performs certain process to determine the location of the emitter,which has the advantages of low power consumption,low interception rate,good concealment,etc.,has attracted a lot attention and utilization in military and civil fields.The direct position determination algorithm uses the raw received signal to locate the emitter,and has better performance than the traditional indirect localization algorithm in the complex electromagnetic environment.In the practical scenarios,it is necessary to accurately locate multiple emitters while the related research is not sufficient.Therefore,it is of great significance to study the direct localization algorithm of multiple emitters in distributed radar systems.This thesis focuses on the multiple emitters localization problem for distributed radar systems by studying the direct position determination methods respectively based on multiple signal classification along with target location extraction algorithms and joint estimation of position and signal parameters of multiple emitters.The specific work contents are as follows:In the distributed radar systems,aiming at single emitter localization,the direct position determination algorithm based on the raw received signal is studied.The method jointly processes the received signal at the stations to construct cost function,and obtains the target position by optimizing the cost function.The performances of the traditional indirect algorithm based on time difference of arrival and the direct position determination algorithm are compared using Monte Carlo simulation experiments.Aiming at the multiple emitters localization problem for distributed array radar systems,under the condition that the number of emitters is unknown,a direct position determination method for multiple emitters based on the image expansion algorithm is proposed.By constructing the cost function based on the multiple signal classification algorithm and extracting the position coordinates of the peak points of the cost function plane by the image expansion algorithm,the target detection and the determination of the position of all the targets are completed at the same time.Aiming at the localization for emitters which transmit multiple linear frequency modulation signals,an optimal high-dimensional parameter estimator based on maximum likelihood criterion is firstly derived.In order to reduce the computational cost of the estimator,an effective dimensionality reduction strategy is proposed,whereas a direct position determination algorithm for multiple emitters transmitting linear frequency modulation signals based on fractional Fourier transform is proposed.The target position and corresponding transmitted signal parameters of the multiple emitters are jointly solved to achieve fast-speed and high-precision.The above work has been verified by computer simulation.The Monte Carlo simulation results show that the multiple emitters localization algorithms studied in this thesis can achieve high-efficiency and high-precision in positioning multiple emitters in distributed radar systems.