In this paper, the interpolation procedure is applied in the case of GPS ephemerides, usually available in tables, where the data is provided in 5 or 15 minutes interval. Some GPS applications need ephemerides data in less spaced intervals. Many interpolations methods have been used to generate GPS satellites position and velocity in intermediate points of the tables. The interpolation methods used in this work are the polynomial and trigonometric ones and they will be applied on the IGS rapid ephemerides, with 24 hour total data spaced each 5 minutes, containing GPS satellite positions (x, y and z coordinates) in two coordinate frames: Earth-centered fixed (ECF) and inertial frame. Tests for determining the optimum number of interpolation terms were made. Both function types applied in interpolation tests worked well, but trigonometric interpolation was the most appropriate when applied on GPS ephemerides available in the SP3 files from IGS. In this case, 7 terms in the interpolating function was the most accurate result with source ephemerides in the inertial frame. The most accurate result found for polynomial interpolation occurred with 9 and 11 terms in the interpolating function.
GPS; Interpolation; Ephemeredes
