Developing a Gnss Suite for Geodetic Applications

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Global Navigation Satellite System (GNSS) is one of the most innovative and practical technology developed today. Since its inception it has grown to provide not only world-wide, all-weather navigation, but precise position determination capabilities to all manner of users especially for surveying and geodetic applications. In surveying and mapping, this represents a revolutionary departure from conventional surveying procedures, which rely on observed anglesand distances,for determining point positions. The scope of GNSS is enormous: from data acquisitions and processing, to detailed Computational algorithm in position estimations. Many processing software or applications both scientific and commercial have been developed for GNSS post-processing. These software are developed for general applications or standards and might not meet a country‟s mapping specifications particularly Africa. This means, that the inherent accuracy of a GNSS receiver can be enhanced or degraded depending on which software is used to do the post-processing. Besides, these software tend to be limited to the institutions that wrote them and use of them can require a considerable investment in time to understand the software and how best to use it under various circumstances. Expert training is often recommended by the distributors. In the light of these setbacks and limitations, a GNSS suite, ‘GeoSuite’for geodetic applications such as, GNSS data post-processing, Datum transformationandDirect and Inverse geodetic computationsforGhana,has been developed.The suite is a standalone windowbase application with a user-friendly interface written in Matlab.TheGNSS data post-processing application of the Suite is based on both code andphase observables, and on double differences between simultaneous observations using Rinexfile as an input GNSS raw data.In addition, the Datum transformationapplicationof the Suiteis also centered on the WGS 84 and War Office ellipsoidsusing the 3,5, 7 and 10 transformation parameters, publishedby the Survey and Mapping Division of Ghanaas default transformation parameters or user-defined transformationand ellipsoidparameters. The suite was tested on field measurements and existing coordinates,and from the results obtained it was concluded that, GPS data can be successfully processed using the developed suite for survey workin Ghanaand can perform any form of transformation on the WGS 84 and the War Office ellipsoids or user-defined ellipsoid.The Suite can easily be adapted for other countries particularly within the Africacontinent.
A Thesis submitted to the Department of Geomatic Engineering Kwame Nkrumah University of Science and Technology in Partial fulfillment of the requirements for the of Master of Science Department of Geomatic Engineering College of Engineering. 2013