Measuring GNSS accuracy using SAPOS RTK network

Author: Renata Barradas Gutiérrez

Every year, the Council of European Geodetic Surveyors (CLGE) organises a student contest aimed at rewarding young people for their work in various surveying-related areas. This year, the CLGE Students' Contest was awarded at INTERGEO in Berlin on 27 September 2017.

The three categories awarded this year were:

• Geodesy and Topography,

• GIS, Mapping and Cadastre and

• Galileo, EGNOS, Copernicus.

Leica Geosystems had the pleasure to support the Geodesy and Topography Award. The awarding paper for this year’s category was: “An investigation into the empirical accuracy of GNSS-NHN heights using SAPOS after the introduction of the GCG2016 as a component of the integrated geodetic spatial reference 2016” by Vitaly Winter, Geodesy and Geoinformation student at the Faculty of Agriculture at University of Bonn, Germany. The awarded paper is a local and practical study which shows the opportunities and accuracy of geodetic GNSS receivers for cadastral and engineering surveying.

The research displays for the first time the achievable accuracy of SAPOS HEPS (Network-RTK) after the introduction of the new geospatial reference 2016 in a scientific investigation using Leica Geosystems GNSS equipment.

The goals and objectives of the investigation were:

• To obtain an empirical accuracy value for GNSS-NHN-heights in a specific region

• Compare target and measured values

• Derive the accuracy of the Quasigeoid model GCG2016 using Leica Geosystems GNSS receivers

• Determine factors on which the accuracy of height measurement depends on.

A Leica GS16 Self-Learning GNSS Smart Antenna and a Leica CS20 Field Controller were used to obtain normal heights by connecting with the network-RTK-service HEPS from the provider SAPOS. 138 official height markers in the Rhine-Sieg-county in North Rhine-Westphalia, Germany were measured. The used data type collected included useful information on normal heights, ellipsoidal heights, undulation values, DOP values and measured positions (duration) in the standard Leica Viva format.  

The Leica Geosystems GNSS equipment played a crucial role in achieving the conclusive results of the investigation. “The hardware [of the Leica GS16 and CS20 Field Controller] is reliable and conveniently designed. On top of this, the software settings can be deeply customised to improve reliability and the workflow. The chosen equipment had to receive various satellite systems, such as GPS, GLONASS, Galileo and Beidou with a fast and stable communication,” said Winter.

The results of the investigation test the precise positioning of the Network RTK method used by the satellite positioning service (SAPOS).  The observations concluded a high accuracy and precision of under one centimetre using Leica Geosystems GNSS solutions. “GNSS-technologies are continuously improving so the results of my investigation can be used for comparisons to future investigations or to similar investigations in other regions,” concluded Winter.

Right: The deviation of observations at a single control point showing how accurate the used equipment and services work under favourable conditions. Left: Deviations of the height-markers in the study area in a target-actual comparison.

The Leica GS16 and CS20 Field Controller used attached to a height marker.

For more information about this study, visit: http://www.clge.eu/news/index/150