Aspect of spatial location of permament GPS antennas by using visibility analysis

Spatial configuration of DGPS permanent reference station elements has an effect on performance of the entire system. Arrangement of station elements, such as broadcast antenna and reference masts, requires allowance and further linking together number of technical, operational and terrain factors. Some technical and operational factors as a rule are determined by equipment manufacturer, however terrain factors are conditioned by terrain character of the future reference station site. Terrain character is a composition of its surface shape and all geographical features situated within the reference station surroundings. These factors often can cause certain difficulties during recommended elements' arrangement of the planned reference station. This elaboration presents applications of visibility analysis in planning spatial location of reference station GPS antennas. Visibility, or viewshed, analysis is usually available in various computer programs of Geographic Information System environment. It can be performed from any point situated in three-dimensional space of elaboration range. In the case of such elements as permanent GPS antennas, application of visibility analyses solves a problem of their location with allowance of surroundings and geographical features, which can cause limitation of visibility of satellites and occurrence of multipath. By performing this kind of analyses can be determined threedimensional position of GPS antennas, which meets such requirements as recommended horizon visibility.