System and method for generating precise position determinations

Abstract

A GPS system and method for generating precise position determinations. The GPS system includes a ground based GPS reference system which receives with a reference receiver GPS signals and makes phase measurements for the carrier components of the GPS signals. The GPS reference system then generates and broadcasts an initialization signal having a carrier component and a data link signal having a data component. The data component of the data link signal contains data representing the phase measurements made by the reference receiver. The GPS system also includes a GPS mobile system which receives with a mobile position receiver the same GPS signals as were received by the reference system. In addition, the GPS position receiver receives the data link and initialization signals broadcast by the reference system. The GPS position receiver then makes phase measurements for the carrier components of the GPS signals during and after an initialization period and makes phase measurements for the initialization signal during the initialization period. In response to the phase measurements made by both the reference receiver and the position receiver during the initialization period, the position receiver generates initialization values representing resolution of the integer ambiguities of the received signals. In response to the initialization values and the phase measurements made by both the receivers after the initialization period, the position receiver generates precise position determinations to within centimeters of the exact location.