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Reliability of CSRS-PPP for validating the Egyptian geodetic CORS networks

Abdallah Ashraf, Agag Tarek

Artificial Satellites : Journal of Planetary Geodesy

2022

Vol. 57, No. 1

58--76

The development, utilization, and maintenance of continuously operating reference stations (CORS) network are vital in many areas of surveying and geodesy, such as controlling geodetic networks, developing local ionospheric models, and estimating the tectonic plate movements. Accordingly, the Egyptian Surveying Authority (ESA) established a CORS network consisting of 40 stations covering the Nile valley and its delta in 2011. CORS collect global navigation satellite system (GNSS) data. Recently, Egypt has witnessed rapid growth in many infrastructure projects and the development of new cities on a national scale. Therefore, there is an urgent need to investigate the ESA-CORS accuracy; the quality of data from the ESA-CORS must be considered for monitoring continuous tectonic motion, coordinating changes, and for Egypt’s development plan. Contemporary research worldwide identified considerable benefits of the precise point positioning (PPP) solution of dual- or singlefrequency GNSS data. This study investigates the reliability of using the CSRS-PPP service for three consecutive observation days of 32 ESA-CORS networks in Egypt and the surrounding six international GNSS services (IGS)-CORS. For ESA-CORS, the PPP solution showed a root mean square error (RMSE) value of 6 mm (standard deviation [SD] = 3–4 mm) in east and north; for the height direction, the solution indicated an RMSE value of 22 mm (SD was about 14 mm). At a confidence level of 95%, this study revealed that SD95% was 2 mm in east and north directions and 6-7 mm for the height direction. This study shows that the PPP solution shown from the ESA-CORS stations is associated with two times better for horizontal and four times for the height direction than the delivered form ESA-CORS stations.

Porównanie wyników pomiarów czujnikami inklinometrycznymi z pomiarami GNSS w monitoringu permanentnym przemieszczeń obiektów

Ćwiąkała P., Kudrys J.

Pomiary Automatyka Kontrola

2014

R. 60, nr 3

156--159

W artykule omówiono wyniki pomiarów dwoma systemami. Jednym z nich pochyłomierz elektroniczny, a drugim zestaw odbiorników GNSS. Urządzenia zamontowane są na jednym budynku. Opracowanie wyników polegało na obliczeniu zmian pochyleń obiektu rejestrowanych przez inklinometr i porównanie ich ze zmianami współrzędnych punktów wyznaczonych na podstawie pomiarów satelitarnych wykonanych techniką PPP. Analizy miały na celu wykazanie podobieństwa w rejestrowanych przez urządzenia deformacjach budynku.

: In the paper the results of surveys conducted by means of two surveying systems are presented. One of the systems is a precise electronic inclinometer (Fig. 2), while the other is a set of two GNSS receivers. The devices are installed on one building. The study of the results consisted in calculating changes in the object’s inclinations recorded locally by the inclinometer and comparing them with the changes of coordinates of points marked on the basis of satellite surveys conducted by means of the PPP technique. The analyses were aimed at revealing the similarities in the building deformations recorded by the devices. The surveys were performed on the building which belongs to the AGH University of Science and Technology in Krakow. In Fig. 1A the localisation of the building on the area of the university is presented, whereas Fig. 1B shows the approximate position of the surveying devices on the object. The study presents the results of observations related to the changes in the object’s inclination which were recorded from 22nd March 2013 to 31st March 2013. The unprocessed observation data from the NIVEL device was processed by the comparison of changes in the object’s inclinations in daily intervals. The coordinates of the KRAW and KRA1 points were marked by means of the PPP technique, also in a daily interval. The results of the comparison for the whole analysed period of time- after the subtrac-tion of the average value- are presented in Fig. 4.