Research Article ISSN 2278–0092 Int ernational Journal of Advances in Earth Sciences, Volume 2, Issue 1, 2013, 1-7 © Copyright 2012, All rights reserved Research Publishing Group www.rpublishing.org Assessment of Positional Accuracy of DGPS: A Case Study of Indian School of Mines Dhanbad, Jharkhand, India Pradeep Kumar 1* , Sumit Kumar Chaudhary 2 , Gaurav Shukla 3 and Sunil Kumar 2 1 Department of Physics, IIT (BHU), Varanasi, India 2 Department of Mining Engineering, I.S.M. Dhanbad, India 3 Department of Civil Engineering IIT Roorkee, India *Corresponding Author Email: pradeepph84@gmail.com Abstract: In recent years, Different modern instruments and techniques are used in surveying such as DGPS (Differential Global Positioning System) and Total Stations. These instruments and techniques are used for the planning and designing of different projects in many areas such as developing the township, construction of roads, irrigation, mining etc. The DGPS has provided more accurate, reliable and faster field surveying data. In this paper an attempt has been made to assess the accuracy of DGPS by comparing the data obtained from the Total Station at Indian School of Mines, Dhanbad campus. With DGPS the maximum error of 0.013m, minimum error of 0.002m and average error of 0.004m with standard deviation of 0.00554m is observed in Northing. In Easting maximum error of 0.017m, minimum error of zero meters and average error of 0.005m with standard deviation of 0.00674m is observed. The maximum error of 0.027m, minimum error of 0.005m and average error 0.007 with standard deviation of 0.01526m is observed in Reduced Level. The variation of average area from DGPS data with reference to Total Station data is 1.058sq.m. The DGPS provides the more reliable and accurate data which can be used for medium to small scale maps. The accuracy of data improves with repeated observations and it depends on the taking of averages of data. Keywords: DGPS, Total Station, Accuracy, Error, Maps. 1. Introduction In the earlier days surveying was labour intensive, time consuming and less accurate. The developments of GPS technologies have made the acquisition of highly accurate and reliable data possible with reduced physical efforts. These technologies reduced about one half of project cost and save about two third of the project time, when compared to the conventional methods (Berg, 1996; Kleusberg, 1995; El-Rabbany , 2002). The modern survey instruments like DGPS, Total Stations help in cross checking the data quickly in the field. In the past, a lot of time should consume in the preparation of field book and drawing. In the modern era there is good demand for accurate map from various industries. Differential GPS (DGPS) enhances the positional accuracy of GPS receivers by the calculation and transmission of differential correction for individual satellite data from a permanent ground-based transmitter at known location. Simply, meter level positional accuracies offered by DGPS where as centimetre level accuracy has been found with the addition of a local beacon and carrier-wave phase differentiation. The accuracy of the data collected using the DGPS instruments depends upon the availability of satellites and other environment configuration. Differential processing yields 10-15m with single fix while 3-5m was achieved for positions that average numerous fixes. Many authors investigate the potential of GPS techniques in different field conditions. Lin (2004) used both GPS RTK (real time kinematic) and Total Station for dynamic monitoring of land use. The horizontal accuracies involved with RTK and Total Station system were 14mm+/-4mm and 163mm+/-63mm respectively. Ariza- Lopez and Atkinson-Gordo (2008) have analysed same of the standard methodology for positional accuracy assessment of geographical data base by considering statistical formulation and size of the control sample, the distribution and topology of control elements etc. Alsalman and Ali (2009) discussed about the pseudo-range and accuracy performance of the hand held GPS. It has been found that millimetre accuracy can be achieved by carrier phase while code range can provide a meter level accuracy. Chalam and Murlikrishna (2010) also perform an accuracy assessment of handheld GPS in Ranga Reddy district of Hyderabad and find out that hand held GPS is suitable for small scale mapping. Lee et al. (2013) determine topographic surveying method using RTK-GPS and Total Station in Macro tidal Sand Beach and the results reveals that using RTK-GPS is adequate for accurate beach profile change analysis.