Assessment Study of Using Online (CSRS) GPS-PPP Service for Mapping Applications in Egypt

Abstract

Assessment Study of Using Online (CSRS) GPS-PPP Service for Mapping Applications in EgyptMany applications in navigation, land surveying, land title definitions and mapping have been made simpler and more precise due to accessibility of Global Positioning System (GPS) data, and thus the demand for using advanced GPS techniques in surveying applications has become essential. The differential technique was the only source of accurate positioning for many years, and remained in use despite of its cost. The precise point positioning (PPP) technique is a viable alternative to the differential positioning method in which a user with a single receiver can attain positioning accuracy at the centimeter or decimeter scale. In recent years, many organizations introduced online (GPS-PPP) processing services capable of determining accurate geocentric positions using GPS observations. These services provide the user with receiver coordinates in free and unlimited access formats via the internet. This paper investigates the accuracy of the Canadian Spatial Reference System (CSRS) Precise Point Positioning (PPP) (CSRS-PPP) service supervised by the Geodetic Survey Division (GSD), Canada. Single frequency static GPS observations have been collected at three points covering time spans of 60, 90 and 120 minutes. These three observed sites form baselines of 1.6, 7, and 10 km, respectively. In order to assess the CSRS-PPP accuracy, the discrepancies between the CSRS-PPP estimates and the regular differential GPS solutions were computed. The obtained results illustrate that the PPP produces a horizontal error at the scale of a few decimeters; this is accurate enough to serve many mapping applications in developing countries with a savings in both cost and experienced labor.

An Assessment of Ionospheric Error Mitigation Techniques for GNSS Estimation in the Low Equatorial African Region

“…A new technique in GPS positioning known as precise point positioning (PPP) shows that a user with a single receiver can attain positioning accuracy at centimetre or decimetre level, as compared to differential technique. PPP is very cost-effective since there is no need for observations from local or regional reference stations [1].…”

Analysis of web-based online services for GPS relative and precise point positioning techniques

“…However, this technique has some disadvantages related to PPP technique, such that minimum two or more GPS receivers should be used and the true coordinates of the reference stations should be known. Addition to this, increase of the distance between reference station (base) and rover station has reduced the position accuracy (ABD-ELAZEEM et al, 2011).…”

“…PPP uses undifferenced ionospheric-free both carrier-phase (Ф) and code pseudorange (P) observations collected by dual-frequency receiver for data processing. This technique provides precise positioning by using precise ephemeris and clock products provided by IGS and other organizations and by considering other corrections such as satellite effects (satellite antenna offsets and phase wind-up), site displacement effect (solid earth tides, polar tides, ocean loading, earth rotation parameters) and compatibility considerations (products formats, reference frames, receiver antenna phase center offsets, modeling/observation conventions) (ZUMBERGE et al, 1997;KOUBA and HÉROUX, 2001;KOUBA, 2009;ABD-ELAZEEM et al, 2011).…”

Accuracy Investigation of PPP Method Versus Relative Positioning Using Different Satellite Ephemerides Products Near/Under Forest Environment

“…The primary factors for point positioning accuracy are the baseline length between two receivers and the observation duration. In this context, establishing Continuously Operating Reference Stations (CORS) networks has a significant contribution to the relative positioning (Abd-Elazeem et al, 2011;Rizos et al, 2012).…”