Evaluation of Quad-Constellation GNSS Precise Point Positioning in Egypt

Abstract

ABSTRACT:Commonly, relative GPS positioning technique is used in Egypt for precise positioning applications. However, the requirement of a reference station is usually problematic for some applications as it limits the operational range of the system and increases the system cost and complexity On the other hand; the single point positioning is traditionally used for low accuracy applications such as land vehicle navigation with positioning accuracy up to 10 meters in some scenarios which caused navigation problems especially in downtown areas. Recently, high positioning accuracy can be obtained through Precise Point Positioning (PPP) technique in which only once GNSS receiver is used. However, the major drawback of PPP is the long convergence time to reach to the surveying grade accuracy compared to the existing relative techniques. Moreover, the PPP accuracy is significantly degraded due to shortage in satellite availability in urban areas. To overcome these limitations, the quad constellation GNSS systems namely; GPS.GLONASS, Galileo and BeiDou can be combined to increase the satellite availability and enhance the satellite geometry which in turn reduces the convergence time. In Egypt, at the moment, the signals of both Galileo and BeiDou could be logged with limited number of satellites up to four and six satellites for both Systems respectively. In this paper, we investigated the performance of the Quad-GNSS positioning in both dual-and single-frequency ionosphere free PPP modes for both high accurate and low cost navigation application, respectively. The performance of the developed PPP models will be investigated through GNSS data sets collected at three Egyptian cities namely, Cairo, Alexandria and Aswan.

Reliability of CSRS-PPP for Validating the Egyptian Geodetic Cors Networks

“…They concluded that the PPP solution obtained using (Canadian Spatial Reference System) CSRS-PPP online service produced three-dimensional (3D) root mean square error (RMSE) between 4 and 6 mm. Similar results based on GNSS datasets in Egypt were reported by El Shouny andMiky (2019) andEl Manaily et al (2017). Rabah et al (2016) proposed the utilization of PPP for geodetic datum maintenance and update in Egypt.…”

Performance Assessment of PPP Surveys with Open Source Software Using the GNSS GPS–GLONASS–Galileo Constellations

“…Benefits of multi-GNSS have also been highlighted in [21], in which PPP models were performed using both single and dual frequency measurements from GPS, GLONASS, Galileo, and BeiDou systems and considering three selected stations located in Egypt at different latitudes. The IGS-MGEX final precise products were chosen for the correction of orbital and clock errors, while the final IGS GIMs (Global Ionosphere Maps) were adopted to reduce the effect of the ionospheric delay in the single-frequency (SF) PPP model.…”

Integration of Artificial Neural Network and the Optimal GNSS Satellites’ Configuration for Improving GNSS Positioning Techniques (A Case Study in Egypt)

“…The differential GNSS (DGNSS) technique, which basically requires a reference station (Correa Muñoz and Cerón-Calderón 2018), is widely used to eliminate or mitigate these errors. Besides, GNSS performance can be improved through various factors such as the number of satellites (NOS) (Lemmon and Gerdan 1999, Specht et al 2015, Davidovic and Mijic 2017 and position dilution of precision (PDOP) (Nie et al 2016, Biswas et al 2017, Janowski and Rapinski 2016, Han et al 2014, Teng and Wang 2015 (i.e., satellites configuration), cut-off angle (Teunissen et al 2013), recording interval (Yousef and Alemam 2014), occupation time (Mohamed 2015, McGaughey et al 2017, and GNSS constellations (El Manaily et al 2017, Rabbou andEl-Rabbany 2015).…”