الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Since the establishment of the International GNSS Service (IGS) stations they have been used as a control stations for assigning the Precise Point Positioning (PPP) using one Global Navigation Satellite System (GNSS) receiver which has been increased from day to day This work aims to investigate the positional accuracy of points to be established and used as reference ones using one GNSS receiver taking into consideration the available IGS stations as control points In addition the extent of influence of baseline length on that positional accuracy and its modelling are to be studied So two points inside the campus of Assiut University were selected Each point has been occupied with a GNSS instrument for 24 hours and the observations were recorded The position of each point is assigned with the help of each available IGS station which is used as a reference (control) station Each IGS station has three independent processed and adjusted files (products) of different accuracy depending on the orbital and clock correction parameters These products are in the form of one (IGU, IGR, and final IGS) files whereas the IGU file is used directly as real-time data (ultrarapid) the IGR file (rapid) is used through (17-41 hours) after observation and (final IGS) one is used after 12 to 18 days The collected GNSS observations for each one of both surveying points (MECH and TADN) are processed taking into consideration each IGS station as reference (control) one and the results are three products (coordinates) IGU, IGR and IGS of increased accuracy respectively The most accurate coordinates of both points are estimated by taking all available IGS stations as control stations as a whole for the final IGS product The strength of the achieved positional accuracy of the fixed points (MECH and TADN) has been tested by carrying out observations for a third fixed point of known coordinates with occupying (MECH point) and taking the orientation from the point(TADN) using a total station The differences between the observed and known coordinates of this third point are found in the range of the instrument accuracy, i.e. the present work points have the availability to be considered as highly accurate reference stations Moreover the correlation between the baseline length and the achieved accuracy for both points has been investigated and modelled The model that was developed has been used in various applications Accordingly observations of a known point (MUSHA) are processed using the same available IGS stations which used in assigning of (TADN and MECH) points as control point at the three products (IGU, IGR and IGS) A comparison between the coordinates and point positional errors of observations and the corresponding ones of the applied model has been made and the achieved results are in the acceptable range.