Research On Single-Observer Passive Coherent Location For TDOA/FDOA Measurements Using Illuminators Of Opportunity

As the key part of modern warfare victory,Electronic Reconnaissance can provide the combat center with target features,threat warning and positioning tracking and other information support.When the system itself doesn't radiate electromagnetic waves,the use of illuminator of opportunity to detect the target in a specific area of interest is of vital importance which masters the battlefield initiative Right.Passive Coherent Location(PCL)technology does not require synchronization between multiple stations and transmission of various types of data.It has the advantages of low system cost,good maneuverability and strong flexibility,in terms of engineering is relatively easy to achieve.Based on the PCL model,using the Time Difference of Arrival(TDOA)and Frequency Difference of Arrival(FDOA)in passive location system,this dissertation proposes some parameters estimation algorithms and positioning methods.The method of using TDOA/FDOA to measure parameters has good algorithm superiority by constructing the two kinds of parameters information into nonlinear equations and finally finding the position and speed information of the target.The main content of the dissertation and the result of the work are summarized as follows:1.To solve the problem of the performance degradation of parameter estimation using Generalized Cross-correlation(GCC)method and traditional Cross Ambiguity Function(CAF)method under non-gaussian noise conditions,an estimation algorithm of TDOA/FDOA based on least 1-norm criterion is proposed.In this dissertation,the concept of 1-correlation function is given by using the minimum 1-norm criterion,and a TDOA and a joint TDOA-FDOA estimation algorithms for impulsive noise with heavy-tail are proposed.Simulation results of the system model show that the performance of the proposed algorithm is better than that of the traditional method and Fractional Lower Order Moments(FLOM)method in terms of robustness and estimation accuracy.2.To solve the problem of single-observer Passive Coherent Location for TDOA measurements using illuminators of opportunity is unable to locate signals with narraow bandwidth,a FDOA location algorithm based on maximum likelihood is proposed.Firstly,according to the FDOA measurement equation,the maximum likelihood model is constructed.Then newton iteration method is applied to solve the maximum likelihood model to obtain the estimation of the target position and velocity.The Cramér-Rao Lower Bounds(CRLB)of the proposed algorithm is also derived.Simulation results show that the proposed algorithm's estimation accuracy is possible to achieve the CRLB at moderate noise level before the threshold effect occurs.3.To solve the traditional analytic location methods' estimation accuracy is not good enough for the single-observer location using illuminators of opportunity,a Constrained Weighted Least Squares(CWLS)location algorithm based on TDOA and TDOA/FDOA Measurements is proposed.Firstly,introducing the concept of additional variable,the TDOA and FDOA measurements equations are linearized.Considering the relationship between the additional variable and the target location,the location problem is established as a CWLS model.Finally,the CRLB are also derived.Simulation results show that the proposed algorithm approaches the CRLB at high noise level,and comparing with traditional analytic location method,it has a better estimation accuracy.In addition,the analysis of the number of illuminator of opportunity,Geometric Dilution of Precision(GDOP)contour map,etc.,shows that except the influence of the measurement error of TDOA/FDOA,the information such as the number of illuminator of opportunity,the position and height of the target,also has a significant impact to the positioning accuracy.