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Journal of Geodetic Science

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A theoretical study on the bottlenecks of GPS phase ambiguity resolution in a CORS RTK Network

D. Odijk
  • GNSS Research Centre, Department of Spatial Sciences, Curtin University of Technology, Australia
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ P. Teunissen
  • GNSS Research Centre, Department of Spatial Sciences, Curtin University of Technology, Australia
  • Delft Institute of Earth Observation and Space Systems (DEOS), Delft University of Technology, The Netherlands
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2011-04-04 | DOI: https://doi.org/10.2478/v10156-010-0017-0

A theoretical study on the bottlenecks of GPS phase ambiguity resolution in a CORS RTK Network

Crucial to the performance of GPS Network RTK positioning is that a user receives and applies correction information from a CORS Network. These corrections are necessary for the user to account for the atmospheric (ionospheric and tropospheric) delays and possibly orbit errors between his approximate location and the locations of the CORS Network stations. In order to provide the most precise corrections to users, the CORS Network processing should be based on integer resolution of the carrier phase ambiguities between the network's CORS stations. One of the main challenges is to reduce the convergence time, thus being able to quickly resolve the integer carrier phase ambiguities between the network's reference stations. Ideally, the network ambiguity resolution should be conducted within one single observation epoch, thus truly in real time.

Unfortunately, single-epoch CORS Network RTK ambiguity resolution is currently not feasible and in the present contribution we study the bottlenecks preventing this. For current dual-frequency GPS the primary cause of these CORS Network integer ambiguity initialization times is the lack of a sufficiently large number of visible satellites. Although an increase in satellite number shortens the ambiguity convergence times, instantaneous CORS Network RTK ambiguity resolution is not feasible even with 14 satellites. It is further shown that increasing the number of stations within the CORS Network itself does not help ambiguity resolution much, since every new station introduces new ambiguities. The problem with CORS Network RTK ambiguity resolution is the presence of the atmospheric (mainly ionospheric) delays themselves and the fact that there are no external corrections that are sufficiently precise. We also show that external satellite clock corrections hardly contribute to CORS Network RTK ambiguity resolution, despite their quality, since the network satellite clock parameters and the ambiguities are almost completely uncorrelated. One positive is that the foreseen modernized GPS will have a very beneficial effect on CORS ambiguity resolution, because of an additional frequency with improved code precision.

Keywords: GPS; CORS Network RTK; Ambiguity Resolution; ADOP

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About the article

Published Online: 2011-04-04

Published in Print: 2011-01-01

Citation Information: Journal of Geodetic Science, Volume 1, Issue 2, Pages 143–153, ISSN (Online) 2081-9943, ISSN (Print) 2081-9919, DOI: https://doi.org/10.2478/v10156-010-0017-0.

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