GPS for Establishing Control Points

Abstract

The GPS is satellite based navigation and surveying system for determination of precise position and time, using radio signals from satellites, in real time or post processing mode. It is one of the most widely used space geodetic techniques in surveying. GPS is being used all over the world for numerous applications including navigation on land, in air and on sea, earth quake studies, land slide monitoring, deformation studies, vehicle guidance including development of urban infrastructure. GPS offers advantages over conventional methods because it is highly competitive in geodetic fields, it is likely to replace most of the techniques currently in use for determining precise positions of point more than few tens of km apart. GPS gives position accuracy from meter level to mm level, depending upon the types of receiver used. For the development of infrastructure project, the most crucial task is to establish the precise control point having mm level accuracy. Conventional survey methods found very tedious and cumbersome to carry out this activity. GPS plays significant role in establishing the control points with mm level accuracy for infrastructure project, as there is no need to connect local network to GT stations. Accuracy of the work can be achieved by selecting geodetic GPS receiver, data collection for longer period, data processing in post processing mode and relative positioning. In this paper, one case study will be discussed how GPS can be used effectively to establish the control station.