SOLUTION AND PERFORMANCE ANALYSIS OF GEOLOCATION BY TDOA

One method of geolocation is based on measuring the time difference of arrivals (TDOAs) of a signal received by three of four geostationary satellites. The received signals are cross-correlated to determine the TDOAs and a set of nonlinear equations are solved to produce the loca tion estimate. An exact solution for the transmitter position is deriv ed for the three or four receiver cases. Extension of the solution met hod to more receivers is straightforward. An analysis of the performan ce of the system is given, together with expressions for predicting th e localization mean-square error (MSE) and bias, and the Cramer-Rao bo und. Both precision in TDOA measurements and the relative geometry bet ween receivers and transmitter affect the localization accuracy. The g eometric factors act as multipliers to the TDOA variance in the bias a nd MSE formulae. A study of the dependency of the geometric factors on transmitter position and satellite spacings are provided, as well as simulation results.