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Abstract
In this thesis, a 3rd order geodetic network establishing by using both of the single frequency GPS receiver in differential mode, and traditional total station instrument was investigated, with emphasis on the level of accuracy for each case. Theory of GPS structure, observations, and the error sources were reviewed. Geodetic networks classifications were covered briefly. The adjustment of different networks using the least squares principle; variation of coordinates method; is detailed. Also, a brief description for the Egyptian horizontal classical networks, and GPS networks was presented, including the construction, the adjustment, and the update.
This thesis’s investigations were based on practical field work of establishing a test network including 5 stations in two observation missions: The first mission includes continuous GPS observations for 24 hours on each baseline, using 2 single frequency receivers (10 days of observations). The second mission includes EDM/ theodolite observations for all baselines, using a total station.
According to observations, two networks were created, namely: The traditional network, and the GPS network. The first network was adjusted at first by using the variation of coordinates method three times, according to observations type as Trilateration, Triangulation, and Hybrid network. While the second network was adjusted by using the variation of coordinates method 3 times namely: Commercial Software adjustment, Vectors GPS network adjustment, and Projected network adjustment. All adjustment processes except the commercial software adjustment were carried out using personal built-up software created by the researcher. A comparative analysis for the results was carried out to show the discrepancies between the different adjustment methods.
In order to improve the traditional network results, the GPS observations were used for reorienting the traditional networks to the global UTM direction. Two-dimensional transformation was performed between the hybrid and the GPS network to generate a new network; named the Optimum Network; this network was considered as a standard for the comparison analysis of the traditional and GPS networks. The comparison analysis was carried out based mainly on the criteria of scale, shape, and orientation according to the network type. Results of analysis have shown that, the discrepancies between the GPS and the optimum network was about 13 PPM, while it was 10 PPM, between the traditional and the optimum network ...
The results of this research has shown that the GPS single frequency receivers, using a suitable observation parameters and adjustment techniques, can be used for establishing geodetic network oOrd order, or less, with high reliable precision .