Analysis of sensor-emitter geometry for emitter localisation using TDOA and FDOA measurements

In passive emitter localisation, the accuracy of an estimator is significantly affected by the geometric relationship between the sensors and the emitter. The estimation performance varies with the manoeuvre strategies of sensors, even if the same estimator is utilised to locate an emitter. To achieve desirable performance by providing a guideline for manoeuvring sensors, this study analysed the effects of relative sensor-emitter geometry/velocity for when time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements are utilised to locate an unknown emitter in an electronic warfare (EW) system. The analysis starts with the derivation of a partitioned Fisher information matrix (FIM) from the partial derivatives of TDOA/FDOA measurements. Then, the Cramer-Rao lower bounds on the variances of the estimates for an emitter position and velocity are computed from the submatrices of the FIM. Based on the analyses, the estimation accuracies are investigated according to the relative sensor-emitter geometry/velocity under selected sensor manoeuvre scenarios. Simulations are included to verify the theoretical results, followed by discussions for establishing a sensor geometry and manoeuvre strategy for EW activities.