An Evaluation of the Performance of Network RTK GNSS Services in Ireland

The national Geodetic infrastructure for the island of Ireland has developed rapidly to a fully GNSS compatible coordinate reference system - Irish Transverse Mercator (ITM) which is realised through a Continuously Operating Reference System (CORS) network of active GNSS stations. The National Mapping Authority’s CORS network provides data for post processing and streamed raw data for real-time network (NRTK) solutions. This NRTK raw data is currently being used by both Leica and Topcon to provide independent NRTK solutions. A second CORS network, known as VRS Now Ireland, with both RINEX and NRTK capabilities, was established in 2008 by Trimble and provides users with a third supplier of real-time GNSS solutions. This study is the first in the public domain to evaluate the performance of NRTK services in Ireland and is intended to provide guideline information for geo-spatial practitioners. Based on collecting NRTK data at nine locations within a 50 km radius of Dublin City, and using ’normal’ observing and processing methods, an accuracy of 22 mm ±8 mm with respect to published IRENET 2D coordinates and 29 mm ±14 mm with respect to the IRENET-derived orthometric heights was achieved. The three systems were shown to be generally comparable although some initialization problems were experienced. The addition of GLONASS observables made no significant difference to the results