Monitoring GPS ephemeris data in Jamaica

This Paper includes an investigation of GPS Satellite system physical characteristics. GPS is still a relatively new technology in Jamaica and the Caribbean. To date little if any has gone into the analysis of the Satellites broadcast ephemeris in the Caribbean let alone Jamaica. With this in mind we stage an experiment to collect and analyze GPS ephemeris data for a select period. In this analysis we placed special focus on the variations in the main Keplerian elements that define a Satellite orbit in space. The visibility profile of the GPS Satellites in our location was also noted. Analysis of ephemeris data produced values that are similar to expected ones. The mean value for the Satellites Semi- major axis was 26,559,936.44 m, eccentricities 0.008014 and inclinations 0.957407 radians (54.86deg). The inclination rate has a mean value close to 0 (3.17157E-11) because it is cyclic. Despite the fact that the Longitude of ascending node rate has a negative mean of 8.21107E-9, expected by the nodal regression caused by the Earth´s oblation, the standard deviation was significantly higher than expected with an average value of 2.42852E-10. The absolute mean deviation was 1.64131E-10. The precession velocity of the ascending node has a mean value of 0.001108 radians (0.063 Degrees) per day which is greater than 0.04 Degrees per day recorded in other studies. The visibility profile of the Satellites over a 24 hour period revealed a minimum of 11 available satellites and a maximum of 14 for this location (18.005664 N, 76.744483 W, 0.00 km). This proved to be the typical daily visibility profile for the entire period.