الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Introduction: - Global Navigation Satellite systems (GNSS) has become integral part of all applications. GNSS positioning has different errors and these errors must be resolved to achieve an acceptable accuracy sub centimeters or millimeters. There are three methods of GNSS data processing to reduce or resolve the effect of some of GNSS biases, GNSS observable differencing technique, linear combinations between observables are formed and GNSS biases modeling, this processing may be in real-time or post processing, as will be illustrated in chapter two. Also, some GNSS biases can be resolved through International GNSS Service (IGS) network like Orbit & Sat. clock biases can be fixed by IGS. 2:- Research scope: - Every surveying projects especially geodetic projects are collecting the GNSS raw data and the surveyors need a help to make a decision which GNSS data processing method to use to achieve the acceptable accuracy. Also, if some errors fixed by IGS products which IGS products type can be used, these products may be final (igs) or rapid (igr) or ultra-rapid (igu). GNSS data processing by many software’s that may be commercial or scientific also they may be free. We discus one commercial software (Trimble business center v3.5) and one free online (online CSRS PPP) and help the surveyors if it can be used and which one? to achieve the acceptable accuracy. 3:- Research objective: - To make a comparative study between Precise Point Positioning (PPP) versus relative positioning under different conditions. The conditions or constrains used in this thesis are observation period, base line length and the IGS product type. We apply base line technique in relative solution to spot the errors without adjustment that applied in network technique. 4:- Steps Study: - In order to make a comparative study between Precise Point Positioning (PPP) versus relative positioning, 38 IGS stations were selected for this study. These stations make a centered shape and the base line technique was applied in relative solution. These base lines have different lengths ranging from 128 kms. to 5000 kms. and the BZRG station was taken as a control point for relative solution. All the IGS stations GNSS RINEX data and products are free online through the following link ftp://cddis.gsfc.nasa.gov/. One-day observation (1/1/2015) taken as a sample day for analysis and all the IGS stations data were downloaded with their products like final precise ephemeris (igs18254d.sp3). Also, the RINEX data had been divided into segments with the observation time (24, 20, 16, 12, 6, 4, 2, and 1) hrs. to get the effect of observation time Precise Point Positioning (PPP) versus relative positioning with the base line length. Also, another day observation (1/12/2017) taken as a sample day to see the effect of final and rapid products and all the IGS stations data were downloaded with their products of rapid precise ephemeris (igr19775.sp3). Also, the RINEX data had been divided into segments with the observation time (24, 18, 12, 6, 4, 2, and 1) hrs. to get the effect of observation time Precise Point Positioning (PPP) versus relative positioning with the base line length. 5:- Summary of Study:- The technique of Precise Point Positioning (PPP) is a viable alternative to differential methods for precise positioning using Global Navigation Satellite Systems (GNSS). PPP is very cost effective since there is no need for data from local or regional reference stations. Especially in remote areas the logistic is greatly simplified. The PPP method has a potential for centimeter accuracy for static applications and sub-decimeter accuracy for kinematic applications.