Precise Point Positioning and Differential Solutions by Online GNSS Calculation Tools and RTKLIB: A Comparative Study

The recent advances in GNSS positioning of the recent decades have been possible by the development of increasingly efficient software and online calculation tools. The differences between these online PPP calculation tools result in a different level of performance. Our study shows that for 24-hour or 6-hour observation time, the Canadian Spatial Reference System for PPP (CSRS-PPP), CenterPoint RTX Post-Processing (RTX), Magic/GNSS, Institut Geographique National-PPP (IGN-PPP) and RTKLIB tools have almost similar level of performance with International Terrestrial Reference Frame (ITRF) solutions considered as reference solution. Average deviations on the three components X, Y and Z for the different tools compared to ITRF solutions do not exceed 1 cm. However, the CSRS-PPP tool gives deviations of less than 5 mm. Calculations from the observations of 2 h and 1 h show that the RTX and CSRS-PPP tools keep deviations similar to those obtained with 24 h and 6 h, while RTKLIB and IGN-PPP give deviations exceeding 6 cm and sometimes failures of some calculations for IGN-PPP.

GNSS Technology’s Contribution to Topography: Evaluative Study of Gaps between Methods Topographies

New information and communication technologies have led to the emergence of new techniques in our daily lives. Indeed, in topography, a lightning development of new techniques and new devices has been noticed. This development has given rise to a multitude of choices of devices and various classes of precision. This implies that the decision-makers have to study the adequate equipment and the appropriate technique according to the topographic task to be realized. The objective is not to compare GNSS and topographic techniques, but to point out the contribution of the Global Navigation Satelite System (GNSS) techniques of topographic work. Thus, a theoretical study with a critical eye on the scientific principle of calculating the third topographic dimension followed by a leveling campaign, Real Time Kinematic (RTK) surveys will be used in order to be able to compare and interpret the result from these campaigns. The study of the difference resulting from the practical campaigns will allow us to identify the contribution of GNSS technology.

Migration of the ICS Local Terrestrial Reference System to RRS04

In order to comply with the recommendations of the new mining code, as well as to facilitate data acquisition and exchange, and to guarantee the reliability of these data, the Chemical Industries of Senegal (named ICS) have decided to switch from their local terrestrial reference system to the Senegalese terrestrial reference system created in 2004 and called RRS04. This move allows ICS to take advantage of new measurement techniques such as GNSS and a more global terrestrial reference system. A combination of geodesy with the least squares method was implemented for the resolution of the problem and the optimization of the solution. For this purpose, a GNSS observation campaign was carried out on selected points. The raw data obtained were processed with the Leica Infinity 3.0 software before being used in our calculations for the estimation of the parameters of this passage which has many stakes for the ICS. The obtained results were then presented, applied before being checked and validated.