Radio direction-finding using time of arrival measurements.

摘要

A method and a system for radio direction-finding by measuring the Time of Arrival (ToA) of the leading edge of signals from a distant source at two relatively closely spaced receiving elements. In order to give a good degree of immunity to multipath, the times at which the instantaneous detected amplitudes of the received signals first exceed a minimal threshold value such that received signals can be satisfactorily distinguished from noise is measured in such a manner that the measured time is not affected by multipath which involves more than a few metres additional path length for the indirect, delayed signal. A suitable timing circuit is disclosed. By making ToA measurements on three coplanar, non-collinear receivers, directions of incidence in three dimensions can be determined. A method and a system using both ToA and phase-difference measurements can provide the accuracy of interferometry but be simpler and cheaper.