The Application of GPS Technique in Determining the Earth’s Potential Field

Two approaches to determining the Earth’s external potential field by using GPS technique are proposed. The first one is that the relation between the geopotential difference and the light signal’s frequency shift, between two separated points, is applied. The second one is that the spherical harmonic expansion series and a new technique dealing with the “downward continuation” problem are applied. Given the boundary value provided by GPS “geopotential frequency shift” on the Earth’s surface, the Earth’s external field could be determined based on the “fictitious compress recovery” method. Given the boundary value derived by on-board GPS technique on the satellite surface, the Earth’s external field could be determined by using a new technique for solving the “downward continuation” problem, which is also based on the “fictitious compress recovery” method. The main idea of the “fictitious compress recovery” is that an iterative procedure of “compress ” and “recovery” between the given boundary (the Earth’s surface or the satellite surface) and the surface of Bjerhammar sphere is executed and a fictitious field is created, which coincides with the real field in the domain outside the Earth. Simulation tests support the new approach.