الفهرس 
chapter 1 : introductionOnly 14 pages are availabe for public view
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Abstract
:-Introduction: - The advent of satellite geodesy is one of the greatest technological inventions. The development of Global Navigation Satellite Systems (GNSS), which is a generic term for all the satellite-based global navigation systems at the end of the twentieth century, started a new and exciting era in positioning, navigation, and timing. Accurate estimates of position, velocity, and time have become available to all virtually instantaneously, continuously, inexpensively, and effortlessly. 2:- Research scope: - This research aims to compare between single and dual frequency GPS receivers in geodetic networks 3:- Research objective: - The main objective of this research is to determine the accuracy of single and dual precise point positioning. This will be fulfilled through a number of tasks These tasks can be summarized as follows: 1-Study and improvement the accuracy of single frequency receivers. 2- Comparative study between relative positioning and ppp processing single and dual observations. 4:- Steps Study: - In this research The main goal of this research was to Study and improvement the accuracy of single frequency receivers. And make Comparative study between relative positioning and ppp processing single and dual observations. The first case of study area in this thesis were the 25 IGS stations in Europe. All GNSS RINEX data and products are chosen from the following link ftp://cddis.gsfc.nasa.gov/. 5:- Summary of Study:- The outcomes in view of past Figures demonstrated that there are no critical contrasts in the came about Cartesian arranges if there should arise an occurrence of preparing GPS baselines gathered with static strategy, utilizing single recurrence information, or utilizing double recurrence information L1 and L2 up to benchmark length 42 km. This implies the GPS single recurrence beneficiaries, which are more affordable than the double recurrence recipients, can be utilized as a part of building up GPS first-arrange control systems for pattern length up to 42km.