Utilization of IGS Information for Improved Real-time GPS Positioning

Abstract

Utilization of IGS Information for Improved Real-time GPS Positioning by Francis James Barchesky The estimation of a precise user's position is a difficult and complex problem. In addition, the use of geodetic grade position instruments is often not possible for Small Unmanned Aerial Vehicle (SUAV) systems. However, the availability of the global navigation satellite system (GNSS) and International GNSS Service (IGS) predicted product data allows an attempt to increase the precision of a navigation algorithm, which is the aim in this thesis. The utilization of this information within an algorithm work environment is a complex problem, requiring the development of multiple tools in order to use and access the IGS raw and product data. Therefore, the overall goal of this research project was the development of these tools using MATLAB®. The IGS information provided by these tools allows access to a particular set of product and raw data files. The available predicted product data is used to increase the precision of the position estimate for a real-time application. Within this, the conversion from a long time interval to a fast update rate was determined. The use of this information requires these tools to also include important orbit determinations of the GPS satellites. The use of only precise satellite position information from the developed M ATLAB tools is evaluated by a comparison of a position estimation algorithm using recorded satellite position information and the developed satellite position information from the IGS predicted data. The results show an increase in performance of position estimation with the use of the created MATLAB tools. A discussion in how the use of the created tools could further be expanded to increase the accuracy and precision of a position estimation algorithm is presented. iii Acknowledgements I would like to thank Dr. Marcello Napolitano, my research advisor, for your support, guidance and teachings throughout my education. I greatly appreciate all that you have done for me personally and my education. Dr. Gu, throughout this process our discussions about this graduate project have been invaluable and greatly appreciated. I feel from these a significant improvement has been made within this project. I would like to also thank my other committee member, Dr. Powsiri Klinkhachorn for providing me with helpful feedback. Dr. Srikanth Gururajan and Dr. Brad Seanor your support and encouragement throughout my graduate studies and within the WVU flight testing activities have been greatly appreciated. Thank you so much Steve Raque for your support, advice, and help throughout my undergraduate and graduate studies. To my fellow graduate student in the group: Jason Gross your advisement, discussions, and constant help were all appreciated, Matt Rhudy, your constant help and insight about problems and writing was valued, Matteo Guerra our conversions and help with concepts of GPS was very useful. Zach Merceruio, and Marc Gramlich your construction and development of the PAC aircraft was ...

Effect of Using Different Satellite Ephemerides on GPS PPP and Post Processing Techniques

“…The contributing sources that degrade the performance of accurate GPS position solution include: Earth's atmosphere, satellite clock and orbit errors, geometry of the constellation, radio frequency interference, multipath signals, and receiver clock error (Barchesky, 2011).…”