Visible Star Simulation In Complex Terrain Environment

GPS Application has been very mature, receivers receive GPS satellite signals on theground, the signals are inevitably obscured by artificial or natural objects, so in somerespects or some areas, satellite positioning and navigation technology is still restrictive,as well as navigation accuracy can’t be guaranteed, even can’t be able to determine thelocation of the receiver. Pseudo-satellite positioning technology can significantly enhancethe regional positioning accuracy, however, visible satellites in the region are the premiseson which the distribution of the pseudolite is based.First, the article describes the way how to get digital elevation model (DEM), as wellas introduce the use of Global Mapper.Secondly, introduces some commonly used time-space coordinate system and itstransformation method in the GPS system, correctly understanding of the spatialcoordinates and time coordinate have a major impact on the satellite positiondetermination; ephemeris calculate and ephemeris data are discussed; for a given time andgiven area, gives the way to calculate satellites’ elevation angle and azimuth angle relativeto receivers, in the case of topographic factors, gives the way to calculate elevation angleof obstruction and method to calculate visible satellites; Simulates to generate the carriertrajectory and determines the visible stars in real time.Finally, based on the visible satellite stars of JiuZhaigou area, discusses the feasibilityof distribution of pseudolite based on effectiveness criteria and GDOP, simulates visualdomain in complex terrain environment. According to the pseudolite emplacing methodproposed in this article, gives pseudolite layout scheme. Via contrasting the variety ofGDOP and the number of visible stars, indicates that the distribution of satellites shown inthis paper is effectively and pseudolites can improve the overall navigation systemavailability, reliability, stability, and measurement accuracy.