Research On TDOA Estimation And Passive Localization Technique For High-Speed Maneuvering Emitter

In modern war,the high-precision positioning of the enemy radiation sources is an important prerequisite for guiding the precision strike weapons to destroy the enemy radiation sources and their carriers,thus weakening and destroying the effectiveness of the enemy's electronic equipment,and seizing the control of electromagnetic spectrum in the battlefield.Aiming at the problem of reconnaissance and location of high-speed maneuvering radiation sources,this paper focuses on two key problems: time difference estimation of high-speed maneuvering radiation sources and localization of sources when the receiver position is accurately known / contains errors.The main contents of this paper are given as follows:1.For a high-speed(constant speed)moving emitter,its energy may spread along different range cells within the coherent integration time,leading to the range migration(RM),which makes the TDOA estimation error increases.For this purpose,a novel fast TDOA estimation algorithm based on the sequence reversing transform(SRT)is proposed to circumvent this problem.The basic strategy is to divide the received signals into segments,artificially making the equivalent pulse signals,then employ the sequence reversing transform to remove the RM arising from the target speed,and finally accumulate the target energy into peaks at the corresponding TDOA location.In doing so,the TDOA estimation can be achieved.The proposed algorithm can be efficiently implemented by using complex multiplications,the fast Fourier transform(FFT)and the inverse FFT(IFFT),without any searching procedure.Simulation results validate that the proposed algorithm achieves better TDOA estimation performance for high-speed moving emitters,with a relatively low computational cost.2.For a high-speed maneuvering emitter,its motion will cause the integrated peak expanding and shifting along the range and Doppler frequency dimensions,leading to the RM and Doppler frequency migration(DFM),which makes the TDOA estimation error increases.For this purpose,a novel fast TDOA estimation algorithm based on the sequence SRT and non-uniform fast Fourier transform(NUFFT)is proposed to circumvent this problem.The basic strategy is to employ the sequence reversing transform to remove the RM,and then accumulate the target energy into peaks at the corresponding TDOA location by performing NUFFT along the slow dimension.The proposed algorithm can be efficiently implemented by using complex multiplications,the FFT,IFFT,and NUFFT operations,without any searching procedure.Simulation results validate that the proposed algorithm achieves better TDOA estimation performance for high-speed maneuvering emitters,with a relatively low computational cost.3.For TDOA-based source localization using a number of spatially separated receivers,when there are multiple disjoint sources in the localization scenario and the corresponding TDOA measurements are correlated,localizing each source separately cannot get the optimal results.To solve this problem,a novel algebraic solution is proposed.It is based on the two-step weighted least squares(TSWLS)framework.In the first WLS step,the TDOA measurement equations corresponding to all the sources are linearized by introducing auxiliary parameters,and a rough estimate of source position is obtained.Then in the second WLS step,the constraint relation between the source position and the introduced auxiliary parameters is employed to construct another set of equations,from which the accurate estimate of source position is obtained.A significant difference between the proposed solution and existing algorithms is that the second WLS step of the proposed solution avoids the problem of rank deficiency when solving the inverse matrix,and does not need additional square operation.The theoretical analysis shows that the localization error of the proposed solution attains the Cramér-Rao lower bound(CRLB).Simulation results demonstrate that the localization accuracy and robustness of the proposed solution are better than existing algorithms.4.For the TDOA-based positioning of multiple disjoint sources in the presence of receiver position errors,an improved TSWLS algebraic solution is proposed.The proposed algorithm follows the basic framework of TSWLS.However,compared with the conventional TSWLS algorithm,the proposed algorithm employs a different linearization technique in the second WLS step,by which the additional square operation and the problem of rank deficiency when solving the inverse matrix are avoided.Simulation results demonstrate that the proposed solution analytically achieves the CRLB performance for multiple disjoint sources in the presence of sensor position errors,and has lower localization errors and higher robustness than the existing algorithms.5.In order to reduce the influence of receiver position error on TDOA-based source positioning,a new receiver position error calibration algorithm is proposed.The proposed algorithm uses the TDOA measurements of the calibration sensors and the ones of unknown sources,to construct the linear equation of the receiver position error.Combined with the statistical characteristics of the receiver position error,the proposed algorithm uses the Bayesian Gauss–Markov theorem to solve the equation,obtaining the linear minimum mean square error(LMMSE)estimate of the receiver position error.Simulation results demonstrate that the proposed algorithm has better calibration performance than existing algorithms.