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For the most accurate ray-tracing in an anisotropic ionosphere with realistic 3D electron density gradients, it is found that the ionosphere model should be a continuous function of the spatial co-ordinates and thus also the electron density. The spatial derivatives of the refractive index should also be continuous for first, second and higher order derivatives. To perform ray-tracing in a 3D ionosphere...
Ray tracing technique can be used to determine the effect of Earth's magnetic field to (Global Positioning Systems (GPS) signals with and without the presence of ionospheric horizontal gradient. In this project, Jones 3D Ray Tracing program was employed to study the effect of the ionosphere on GPS rays (L1 and L2). The group path or delay is obtained from the difference between the distances of the...
The ionospheric horizontal gradient is the variation of electron density with latitude and longitude which can cause the azimuthal deviation of the Global Positioning System (GPS) ray path. In this paper, the improvement in Differential GPS (DGPS) positioning will be shown by applying the ionospheric horizontal gradient correction to the carrier phase measurement from each GPS satellite. The ionospheric...
Over the equatorial region, the inhomogeneous formation of the ionosphere introduces greater ionospheric horizontal gradient which could give greater positioning error for a user station in a DGPS system. Furthermore, the difference in the elevation angle of the user station that `views' the same GPS satellite as the reference station also introduces range measurement errors at mm to cm levels. In...
GPS ray propagates at two carrier frequencies; L1 at 1575.42 MHz and L2 at 1227.6 MHz. In this project, Jones 3D Ray Tracing program being used to determine the characteristics of the GPS ray as it propagates through the ionosphere. A numerical mathematical model which is continuous and contains no singularities has been used to represent the actual formation of the ionosphere in 3 dimensional (latitude,...
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