APPP

Starting point, Contents and goals

The APPP project aims at the development of a user-friendly smartphone application that enables the user to perform GNSS positioning down to the decimeter range in near-real-time using state-of-the-art PPP (Precise Point Positioning) algorithms. By means of an extensive test phase and further development of the algorithms, the basis for a future app that can be used by a large number of end devices is to be laid, which can be given wide market opportunities.

Methods

The advantage for the participating companies lies in the integrated interface, which uses atmospheric correction data from the EPOSA GNSS service (provider Wiener Netze GmbH.) and additionally obtains global correction data from the Galileo High Accuracy Service (HAS). This ensures clear independence from third-party providers.

Until 2016 it was not possible to access the raw GNSS measurement data from Android smartphones and only the coordinates of the device's internal "black box" positioning could be read out. Now the GNSS observations of the smartphone can be used directly to estimate the user position with correction data and self-developed algorithms. The technique of PPP will be used for this purpose.

Unlike relative positioning techniques, PPP do not require nearby reference stations, as the precise satellite products (orbits, clocks and biases) used are globally valid. Therefore, regardless of the user position, the same data must be transmitted in only one direction. In addition, the concept of PPP is very flexible, which is a great advantage considering the challenging nature of GNSS measurements from smartphones.

Since most smartphones are equipped with simple, cost-effective GNSS chips and antennas, their GNSS measurements (especially phase measurements) are of low quality. Problems are, for example, cycle slips, high noise, outliers or multipath effects. Furthermore, most smartphones on the market offer GNSS measurements on just one frequency.

Normally, PPP eliminates the ionospheric propagation delay, one of the major sources of error in GNSS measurements, by utilizing the ionosphere-free linear combination based on dual-frequency observations. Thus, a high-quality ionosphere model in real-time is required for the specific application. Such a model is already being generated routinely on a daily basis in cooperation between Wiener Netze and the TU Wien.

Expected results

Taking advantage of to the current research in the field of PPP at TU Wien, a PPP positioning procedure is to be developed within the framework of this project, which will allow dm-accurate positioning in near real-time on the basis of challenging measurement data and by obtaining global and regional model parameters via the server of the project partner Wiener Netze GmbH..

Coordinator

TU Vienna - Department for Geodesy and Geoinformation

Project partner

• Upstream- next level mobility GmbH.
• Wiener Netze GmbH.

TU Vienna
Department for Geodesy and Geoinformation
Ao. Univ. Prof. Dr. Robert Weber
Wiedner Hauptstrasse 8-10 /E120-4
A-1040 Wien