| Passive location of emitter sources has many advantages such as long detected distance, much better security, uneasy to disturb compared to active location. As the developments in measurement and signal-processing technology, the TDOA(Time Difference of Arrival) and FDOA(Frequency Difference of Arrival) location technology is playing a more and more important role in electronic warfare.TDOA and FDOA location technology is studied in this thesis. The main contents are as following.Based on the configuration of the locating system with three satellites, the theory and analysis of accuracy in time difference and frequency difference location methods are studied in this thesis. The general formula of location accuracy is derived from GDOP, especially with the relationship of measurement errors, the position error and velocity error of stations.As for static positioning algorithms, A closed-form of TDOA passive location algorithm, a maximum likelihood (ML) localization of FDOA algorithm, a joint localization of TDOA and FDOA based on maximum ratio combining (MRC) are studied and their performances are analyzed and compared with each other in details. The simulation results shows that the capability of combined TDOA and FDOA measurements is better than TDOA also FDOA measurements.Concerning dynamic positioning algorithms, Kalman filter is applied to TDOA and FDOA measurements with four satellites and estimate the position and velocity of dynamic sources. Kalman filter can obtain satisfactory position and velocity estimations when the initialized position is appropriate. |
