Original Article

GPS Solutions

, Volume 10, Issue 1, pp 45-55

First online:

Accuracy of OPUS solutions for 1- to 4-h observing sessions

  • T. SolerAffiliated withNational Geodetic Survey, NOAA Email author 
  • , P. MichalakAffiliated withWarsaw University of Technology, Institute of Geodesy and Geodetic Astronomy
  • , N. D. WestonAffiliated withNational Geodetic Survey, NOAA
  • , R. A. SnayAffiliated withNational Geodetic Survey, NOAA
  • , R. H. FooteAffiliated withNational Geodetic Survey, NOAA

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We processed 30 consecutive days of Global Positioning System (GPS) data using the On-line Positioning Users Service (OPUS) provided by the National Geodetic Survey (NGS) to determine how the accuracy of derived three-dimensional positional coordinates depends on the length of the observing session T, for T ranging from 1 h to 4 h. We selected five Continuously Operating Reference Stations (CORS), distributed widely across the USA, and processed the GPS data for each with corresponding data from three of its nearby CORS. Our results support the current OPUS policy that recommends using a minimum of 2 h of static GPS data. In particular, 2 h of data yielded a root mean square error of 0.8, 2.1, and 3.4 cm in the north, east, and up components of the derived positional coordinates, respectively. Results drastically improve for solutions containing 3 h or more of GPS data.


GPS Processing services OPUS Position relative to observation time