RA-PPP - Innovative Algorithms for Rapid Precise Point Positioning

Is there a chance to achieve dm accuracy in positioning, just by means of an isolated single-frequency GNSS receiver? Which further external data has this isolated receiver to be provided with and within what time frame does the position determination converge to the requested accuracy? These are the crucial questions of Precise Point Positioning (PPP). In the project RA-PPP we show that there are several limiting factors to existing PPP algorithms and services, which rely on highly precise orbit and clock parameters.

Short Description

Using these external data sources, inaccuracies in the orbit and clock information as well as atmospheric uncertainties can be circumvented. Furthermore, with a dual frequency receiver - eliminating ionospheric effects - centimeter to decimeter accuracy can be achieved. Compared to DGPS and RTK systems, PPP reduces the user’s costs - neither a base station nor simultaneous observations are necessary - and local limitations, thanks to at least regionally or even globally valid corrections.

Based on a preliminary analysis of existing PPP services, algorithms and products the scientific members of the RA-PPP consortium (Graz University of Technology and Vienna University of Technology) develop improved and innovative algorithms for rapid PPP.

Particular attention is paid to the attribute "rapid", since nowadays PPP systems can provide accuracies up to centimeter level by long observation periods. Even decimeter accuracy is achievable only after almost half an hour, which makes PPP unusable for a wide range of applications.

Based on their contribution to a PPP error budget and the current deficiencies in data modeling, the following approaches are pursued to achieve improved accuracies and faster convergence of the PPP solution:

the derivation of improved atmospheric models for single frequency users
the use of "regional clocks"
the use of new ionospheric free linear combinations with reduced phase noise
a simulation to solve for ambiguities by introducing apriori receiver and satellite dependent bias tables

The newly developed algorithms are implemented into a PPP user module for static and kinematic observations by TeleConsult Austria GmbH. This module is further used to evaluate the performance of the algorithms in terms of convergence time, accuracy and availability, whereby all necessary data is provided by Wienstrom GmbH.

Project Partners

Coordinator

Graz University of Technology, Institute of Navigation and Satellite Geodesy - Christoph Abart

Partners

Vienna University of Technology, Institute of Geodesy and Geophysics - Prof. Robert Weber
TeleConsult Austria GmbH - Philipp Berglez
WIENSTROM GmbH - Christian Klug

Contact Address

Graz University of Technology - Institute of Navigation and Satellite Geodesy
Christoph Abart
Steyrergasse 30
A-8010 Graz
E-mail: christoph.abart@tugraz.at
Web: www.inas.tugraz.at