CHIRPED SPREAD SPECTRUM POSITIONING SYSTEM

摘要

Positioning system for locating a mobile body (MU) comprising a plurality of earth based spread spectrum (SS) broadcasting stations (10-1...10-N) arranged geographically in a cellular pattern. Each SS broadcasting station (10-1) includes a modulator providing a channel signal structure which is substantially orthogonal with respect to adjacent stations in the cellular pattern, each channel signal including navigation beacon data including a unique beacon identification, station latitude and longitude, time slot and phase stations. In one embodiment, each modulator provides a chirped SS signal in which the navigation beacon is a frequency tone that is repeatedly swept over a selected frequency band for each station. A receiver on the mobile body (MU) receives the SS signals from at least three of the SS broadcasting stations (10-1...10-N) and determines the location thereof. A fourth SS broadcasting station provides altitude. GPS satellite signals can be used for timing control.