Atmospheric Models Applied to DGPS and RTK Network in Brazil: Preliminary Results

Several positioning techniques have been developed to explore the GPS capability to provide precise coordinates in real time. However, a significant problem to all techniques is the ionosphere effect and the troposphere refraction. Recent researches in Brazil, at Sao Paulo State University (UNESP), have been trying to tackle these problems. In relation to the ionosphere effects it has been developed a model named Mod_Ion. Concerning tropospheric refraction, a model of Numerical Weather Prediction (NWP) has been used to compute the zenithal tropospheric delay (ZTD). These two models have been integrated with two positioning methods: DGPS (Differential GPS) and network RTK (Real Time Kinematic). These two positioning techniques are being developed at São Paulo State University (UNESP), Brazil. The in-house DGPS software was already finalized and has provided very good results. The network RTK software is still under development. Therefore, only preliminary results from this method using the VRS (Virtual Reference Station) concept are presented.

[1]  Choi Look Law,et al.  Development and assessment of GPS virtual reference stations for RTK positioning , 2003 .

[2]  Dennis Odijk,et al.  Precise GPS Positioning by Applying Ionospheric Corrections from an Active Control Network , 2000, GPS Solutions.

[3]  Claudinei Rodrigues de Aguiar.  Modelo regional da ionosfera (MOD_ION): implementação em tempo real , 2005 .

[4]  Matthew D. Powe,et al.  Use of Numerical Weather Prediction Fields for the Improvement of Tropospheric Corrections in Global Positioning Applications , 2003 .

[5]  Dennis Odijk,et al.  Weighting Ionospheric Corrections to Improve Fast GPS Positioning Over Medium Distances , 2000 .

[6]  Günther Retscher,et al.  Accuracy Performance of Virtual Reference Station (VRS) Networks , 2002 .

[7]  Yang Gao,et al.  Ionosphere Effect and Modeling for Regional Area Differential GPS Network , 1998 .

[8]  Luiz Paulo Souto Fortes,et al.  Optimizing the Use of GPS Multi-Reference Stations for Kinematic Positioning , 2002 .

[9]  Police Department,et al.  Salt Lake City , 1895 .

[10]  Peter Teunissen.  Quality Control in Geodetic Networks , 1985 .

[11]  Gerhard Wübbena,et al.  Reducing Distance Dependent Errors for Real-Time Precise DGPS Applications by Establishing Reference Station Networks , 1996 .

[12]  Jaume Sanz,et al.  Wide‐Area, Carrier‐Phase Ambiguity Resolution Using a Tomographic Model of the Ionosphere , 2002 .

[13]  J. Raquet.  Development of a Method for Kinematic GPS Carrier-Phase Ambiguity Resolution Using Multiple Reference Receivers , 1998 .

[14]  Erin E. Dooley,et al.  Center for Ocean-Land-Atmosphere Studies , 2004 .

[15]  Christopher Champion Varner,et al.  DGPS carrier phase networks and partial derivative algorithms , 2000 .

[16]  G. Fotopoulos.  Parameterization of DGPS Carrier Phase Errors Over a Regional Network of Reference Stations , 2000 .

[17]  H. van der Marel,et al.  Virtual GPS Reference Stations in the Netherlands , 1998 .

[18]  Gérard Lachapelle,et al.  The Effects of Network Geometry on Network RTK Using Simulated GPS Data , 2003 .

[19]  Paulo de Oliveira Camargo.  MODELO REGIONAL DA IONOSFERA PARA USO EM POSICIONAMENTO COM RECEPTORES GPS DE UMA FREQÜÊNCIA , 2005 .

[20]  Lambert Wanninger,et al.  The Performance of Virtual Reference Stations in Active Geodetic GPS-networks under Solar Maximum Conditions , 1999 .

[21]  M. Cannon,et al.  Spatial and Temporal Characteristics of DGPS Carrier Phase Errors Over a Regional Network , 2000 .

[22]  João Francisco Galera Monico,et al.  Utilização do Software GPSeq na Solução Rápida das Ambigüidades GPS no Posicionamento Relativo Cinemático de Bases Curtas , 2002 .

[23]  Luiz Danilo Damasceno Ferreira,et al.  Application of ionospheric corrections in the equatorial region for L1 GPS users , 2000 .

[24]  D. Zhong,et al.  Robust estimation and optimal selection of polynomial parameters for the interpolation of GPS geoid heights , 1997 .

[25]  Anna B. O. Jensen,et al.  Integrating Numerical Weather Predictions in GPS Positioning , 2002 .

[26]  T. Başar,et al.  A New Approach to Linear Filtering and Prediction Problems , 2001 .

[27]  Guenter W. Hein,et al.  Improved Tropospheric Delay Modeling Using an Integrated Approach of Numerical Weather Models and GPS , 2000 .