Research On Signal Processing Technology Of Difference Time Multi-Station Passive Location

DTOA(Difference Time Of Arrival) location system,which is also named the dual-curve location system,is a vital passive location method.It is based on the time difference of signal arrived to differe- nt stations received by three or more stations to determine the position of the target wanted to be loca- ted.It boasts of its low probability of being captured because it does not radiate electromagnetic wave. it does not exist location hole for it does not have power overlay and clutter.At the same time,it boas- ts of its low probability of being captured because it does not radiate electromagnetic wave. DTOA s- ystem is also featured in the capacities,such as inherent anti-interference,anti antiradiationmissile,anti low-level defence and anti invisible weapons. It plays increasingly important role in electronic counter measure for its advantages and survival ability.The accuracy of DTOA system is affected by the estimate of time difference.So research on high-speed and exact estimate of time difference beco- mes an important subject of DTOA. The principal contributions are summarized as follows:Firstly,basic principle of DTOA and almost all classical based location algorithms areintroduced. The impacts that DTOA measurement error and baseline length and collocation of station which bring to location accuracy are analyzed,then methods of improving location accuracy are brought forward. the problems of ambiguity and non-solution in basic DTOA location technology are studied. Location by combineing time difference and direction measure is intrduced in order to improve location accura- cy, uses the elevation angle of the target as a new measurement to form a redundant location system c- onsisting of three subsystems. Each subsystem can obtain a set of location result s with ambiguity. A better performance can be achieved after eliminating the ambiguity and processing the location results by SWLS fusion.The second part of this paper is to discuss two modes of time difference measurement:the method based on the signal synchronization and the method based on the time synchronization.For the first m- ode,Signal-correlating arithmetic(include basic Cross-Correlation and Generalized Cross-Correlation) and adaptive time delay estimation is discussed. For the second mode,time of arrive estimation based on correlation algorithm and Haar wavelets transform are recearched after the introduction of time sy- nchronization. Pulse pairing of HPF signal is discussed, according as radar netting and partition to airspace,the approach is able to reduce false pairing extraction and improve ambiguous location eff- ective.The second part of this paper is to recearch nonlinear filter technology. a novel nonlinear filter was proposed to improve convergence speed and estimation accuracy. The backward prediction and the state update procedure improve the estimation accuracy of the last state estimate and reduce the c- urrent state prediction error. A more accurate current stateestimate could be gotten with more precise initial condition.Finally,an overview of the work and the prospect of the technique of DTOA passive location are presented.