Abstract: Systems and methods are disclosed for ionospheric correction in a system employing a single GPS frequency receiver for determining the geographic location of an object on the earth's surface. The receiver receives signals transmitted at the GPS L1 frequency from at least first, second and third GPS satellites, the first, second and third satellites having respective orbital positions relative to the receiver such that the total electron count (TEC) contribution to ionoshperic interference to signals transmitted by the respective satellites and received by the receiver is approximately the same. Respective measured distances of the three satellites to the receiver are determined based on the actual signal transmission times. True distances of the respective satellites are then calculated based on the assumption that the TEC contribution to the interference from each satellite is approximately the same.

Abstract: Systems and methods are disclosed for ionospheric correction in a system employing a single GPS frequency receiver for determining the geographic location of an object on the earth's surface. The receiver receives signals transmitted at the GPS L.sub.1 frequency from at least first and second GPS satellites, the first and second satellites having respective orbital positions relative to the receiver such that the total electron count (TEC) contribution to ionoshperic interference to signals transmitted by the respective satellites and received by the receiver is approximately the same. Respective measured distances of the two satellites to the receiver are determined based on the actual signal transmission times. True distances of the respective satellites are then calculated based on the assumption that the TEC contribution to the interference from each satellite is approximately the same.