Research On Airborne Passive Location Technologies Based On Doppler Frequency Difference

Passive localization system can detect targets in large range, it works silently and has good concealment, so it is not easy to be attacked by ECM and ARM, the system plays an important role in improving survival ability and fighting ability of the combat command systems in complex electromagnetic environments. Therefore, more and more countries put emphasis on the research of passive localization techniques. The joint passive localization based on Frequency Difference of Arrival (FDOA) is proposed focus on the problems of low positioning accuracy and narrow range of adaptation about single passive localization techniques. Using the airborne platform as the detection platform, the positioning error of single localization technique, the joint localization algorithm and tracking filter algorithm are studied in detail in order to achieve the goal of engineering applications about airborne passive localization based on FDOA. The contents mainly include three aspects as follows:For the analysis of passive localization error, firstly the single localization algorithm of Angle of Arrival (AOA), Time Difference of Arrival (TDOA), Frequency Difference of Arrival (FDOA) are offered, then the Geometric Dilution of Precision (GDOP) formula of these techniques are derived and it is the foundation of follow-up studies.For the research of joint localization algorithms, firstly the high-precision algorithm of frequency estimation which is the premise of algorithm based on FDOA is preliminary studied, then we put forward the improved AOA-FDOA localization algorithm on the basis of traditional algorithm. For the problem of low localization precision of this algorithm which makes the algorithm could not be fulfilled in some systems like fire control system, in this paper an innovative TDOA-FDOA algorithm is proposed, which changes high-order nonlinear equations into ternary linear equations based on probability theory, takes advantage of multiple measurements to improve the localization precision effectively.On the study of tracking filter, in this paper firstly the filtering and tracking mode on two-aircraft TDOA-FDOA localization are established, then the problem of transforming the nonlinear mode into linear mode by theoretical derivation is demonstrated and realized. Simulation results show that this algorithm achieves the goal of proving good performance of the filtering and tracking algorithm for fixed target and moving target, lay the foundation for the engineering application of this algorithm.