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O U T L O O K support a wide realm of activities, the receiver must be a high quality geodetic unit capable of tracking and recording all components of the GPS signal. Rapid advances in GPS technology have enabled the GPS technology to become more robust and versatile. The applications derived from a network of CORS has found use in the determination of precise position on a 24x7 real time basis for civilian use that has been shown to save time and cost of execution of developmental projects. Kinematic (RTK) Positioning was restricted by the effects of the ionosphere and troposphere, which create systematic errors in the raw data over long baselines. In practice, it means that the distance between a rover (mobile) receiver and its reference station has to be quite short in order to work efficiently. The precision of RTK decreases as the baseline length increases. Real Time Network RTK (RTN) surveying has been developed to extend this base-to-rover range limitation. The concept and technology of Virtual Reference Station (VRS) is one of the methods that RTN can be applied wherein the systematic errors (due to Ionosphere & Troposphere) in the reference station data are either reduced or eliminated. This not only allows a user to increase the distance at which the rover receiver is located from the reference, it also increases the reliability of the system and reduces the RTK initialization time. The concept can be used not only to set-up new GNSS networks, but also to improve the performance of old, established GNSS networks. On the other hand para 1.2.v.m of the NLRMP document in Chapter-4 on 'Choice of Software and Standards' states the accuracy standards of survey as: horizontal accuracy of 20 cm for rural areas, 10 cm for urban areas, or better. In both the above norms there is an inherent need to obtain 'better' accuracy standards as well as to 'achieve the required accuracy levels in the data'. In 2008 when the NLRMP was being prepared the technology in use was the ETS & DGPS technology. These technologies on their own are advanced technologies which are still very much in use. However technology has evolved since then and newer technologies, based on the earlier technologies, come with much better capabilities and accuracies whilst making the data consistent at the same time. With the use of advanced technology it is possible to aspire for better levels of accuracies in parcel coordinates to make it compatible with the ground reality and to fulfil the requirements of the parcel owner. The CORS Technology – Real Time Positioning The GPS Continuously Operating Reference Station (CORS), a term adopted by the National Geodetic Survey, an office of the United States Department of Commerce's National Oceanic and Atmospheric Administration (NOAA), is a sophisticated and advanced GPS based technology that first requires the precise determination of a position on the surface of the earth and then the continuous monitoring of that precise position for the purpose of Geo-scientific studies that include determining the shape of the earth, determining the effect of the earth – moon gravitation on the shape and rotation of the earth, determining the movement of the earth's crust, defining a Spatial reference System and so on. The GPS receiver is the heart of a CORS configuration. In order to Real Time Network RTK – Achieving the Required Accuracy Levels in Survey/Resurvey Operations The evolution of Real Time Network RTK is a giant leap from the DGPS technology mentioned in the NLRMP & the DILRMP documents. High accuracy Real-Time Kinematic (RTK) Positioning with Global Navigation Satellite System (GNSS) is one of today's most widely used precision surveying techniques. This infrastructure is already operational in government and private agencies in many countries and for which there is increasing demand. Earlier, the use of Real-Time Figure 1: Real-Time Network (RTN) Surveying; Image Courtesy of Trimble. G I S R E S O U R C E S | M A R C H 2 0 2 1 2 1

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