Research On Direct Position Determination In Passive Location

Direct position determination is a new technology in passive positioning.This positioning technology is different from the traditional two-step positioning technology.It also uses the received signal in two-step positioning,but does not require the estimation of intermediate parameters.It can give an estimate of the target position directly.The direct position determination is based on the maximum likelihood criterion,establishes the target cost function,and finally searches for the extreme point of the target function through multi-dimensional grid search to obtain the estimated value of the target position.This paper focuses on the direct positioning technology in passive positioning technology.The main research contents are as follows:1.For the traditional two-step positioning technology in passive positioning,the twostep positioning technology based on TOA,TDOA,FOA,FDOA,AOA,etc.was studied,and the methods of estimating delay and Doppler were also studied.2.Aiming at the direct position determination of the emitters in passive positioning,direct position determination of stationary wide-band radio signal based on time delays and Doppler shifts,direct position determination of stationary narrowband radio signal based on Doppler frequency shifts,direct position determination of the emitter based on the array are studied.In the above positioning scenario,the signal model establishment and the derivation of the direct position determination were carried out respectively.Then,in order to solve the problem of the calculation amount of the direct position determination of the emitter based on the array,a fast processing algorithm for the direct positioning of the emitter based on the gradient algorithm was proposed.Furthermore,Cramér Rao Bound is deduced in this positioning scenario,and carried out complexity analysis and simulation experiment verification.3.Aiming at the direct position determination in passive coherent location,direct geolocation of stationary targets using MIMO radar is first studied,and different discussions are made according to whether the receiving station has a prior knowledge of signal waveform and whether the signal is deterministic or random.Then introduced the direct position determination of moving target based on time delays and Doppler shifts,applying the direct position determination to Multistatic Passive Coherent Location Radar Systems,uses the illuminators of opportunity to detect target.Finally,aiming at the huge computational cost of the direct positioning technology of moving targets based on time delay and Doppler shifts,a fast processing algorithm for the direct positioning of the emitter based on the quasi-Newton algorithm was proposed.Furthermore,Cramér Rao Bound is deduced in this positioning scenario,and carried out complexity analysis and simulation experiment verification.The simulation results show that in the above positioning scenarios,direct position determination is significantly better than traditional two-step positioning technology,especially at low signal-to-noise ratio.The fast processing algorithm mentioned in this article is equivalent to the traditional direct position determination,and can approach the CRB asymptotically.