GNSS satellite levelling with use NAWGEO service of ASG-EUPOS System

Uruchomienie testowe wielofunkcyjnego systemu precyzyjnego pozycjonowania na obszarze Polski ASG-EUPOS z początkiem czerwca 2008 roku dało możliwość realizacji prac geodezyjnych w czasie rzeczywistym RTK GNSS (serwis NAWGEO) na obszarze całego kraju. System ASG-EUPOS wprowadza jednolity w skali kraju i niezmienny układ odniesienia. Wyznaczanie pozycji poziomej punktu z wykorzystaniem poprawek serwisu NAWGEO gwarantuje (zgodnie z informacjami właściciela systemu) spełnienie wymagań stawianych dla wszystkich grup dokładnościowych. Wysokości punktów zgodnie z obowiązującymi przepisami powinny być wyznaczane w stosunku do najbliższych punktów osnowy, a kryterium dokładności dla wysokości jest błąd położenia względem najbliższych reperów nawiązania. W pracy przeprowadzono analizy sposobów wyznaczania wysokości w kontekście możliwości technicznych systemu ASG-EUPOS i uwarunkowań prawno-technicznych wynikających z obowiązujących i projektowanych standardów technicznych. Efekt końcowy stanowi propozycja metodyki pomiarów w celu określenia wysokości normalnych w czasie rzeczywistym z wykorzystaniem serwisu NAWGEO systemu ASG-EUPOS z jednoczesną oceną dokładności. Ponadto wykonano analizę dostępnych modeli quasi-geoidy i sposobów ich wpasowania przy realizacji pomiarów wysokości w systemie ASG-EUPOS.The mutifunctional precise satellite positioning system on area of Poland ASG- -EUPOS testing activation with the beginning of June 2008 gives opportunity to realize geodetic jobs in real time RTK GNSS (NAWGEO service) on whole country. The ASG- -EUPOS system establish unified in whole country and invariable coordinate system. Points heighs determination with use of ASG-EUPOS system guarantee (according to system owner) to achieve requirements for all groups of precission. In accordance with obliging regulations points height should be determined with reference to nearest reference point and the precission criterion for heights is position error in reference to nearest benchmarks. In this work height determination methods were analysed in contex of ASG-EUPOS system technical capabilities and legislative-technical conditions following to obliging and designed technical standards. Final effect is the measurement methodology proposal to determine normal heights in real time with use of NAWGEO service from ASG-EUPOS system and precision evaluation simultaneously. Moreover, available quasi-geoid models and methods of its transformation in purpose to realise height measurements in ASG-EUPOS system were analised

Tropospheric refractivity and zenith path delays from least-squares collocation of meteorological and GNSS data

Precise positioning requires an accurate a priori troposphere model to enhance the solution quality. Several empirical models are available, but they may not properly characterize the state of troposphere, especially in severe weather conditions. Another possible solution is to use regional troposphere models based on real-time or near-real time measurements. In this study, we present the total refractivity and zenith total delay (ZTD) models based on a numerical weather prediction (NWP) model, Global Navigation Satellite System (GNSS) data and ground-based meteorological observations. We reconstruct the total refractivity profiles over the western part of Switzerland and the total refractivity profiles as well as ZTDs over Poland using the least-squares collocation software COMEDIE (Collocation of Meteorological Data for Interpretation and Estimation of Tropospheric Pathdelays) developed at ETH Zürich. In these two case studies, profiles of the total refractivity and ZTDs are calculated from different data sets. For Switzerland, the data set with the best agreement with the reference radiosonde (RS) measurements is the combination of ground-based meteorological observations and GNSS ZTDs. Introducing the horizontal gradients does not improve the vertical interpolation, and results in slightly larger biases and standard deviations. For Poland, the data set based on meteorological parameters from the NWP Weather Research and Forecasting (WRF) model and from a combination of the NWP model and GNSS ZTDs shows the best agreement with the reference RS data. In terms of ZTD, the combined NWP-GNSS observations and GNSS-only data set exhibit the best accuracy with an average bias (from all stations) of 3.7 mm and average standard deviations of 17.0 mm w.r.t. the reference GNSS stations.ISSN:0949-7714ISSN:1432-139

advanced gnss processing techniques working group 1

Over the last decade, near real-time analysis of GPS data has become a well-established atmospheric observing tool, primarily coordinated by the EIG EUMETNET GPS Water Vapour Programme (E-GVAP) in Europe. In the near future, four operational GNSS will be available for commercial and scientific applications with atmospheric science benefiting from new signals from up to 60 satellites observed at any one place and time, however, many challenges remain regarding their optimal combined utilization. Besides raw data streaming, recent availability of precise real-time orbit and clock corrections enable wide utilization of autonomous Precise Point Positioning (PPP), which is particularly efficient for high-rate, real-time and multi-GNSS analyses