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Air Force Shares GPS Status at CGSIC at ION GNSS+

September 10, 2014  - By
Image: GPS World

News courtesy of CANSPACE Listserv.

Two U.S. Air Force officers provided a GPS program update at Tuesday morning’s Civil GPS Service Interface Committee meeting plenary session at the ION GNSS+ 2014 conference in Tampa, Florida. Here are some key points from the presentations by Colonel Matthew Smitham, deputy director, GPS Directorate, and Lieutenant Colonel Todd Benson, Commander, Second Space Operations Squadron:

  • 31 primary satellites on orbit, 7 satellites in residual status, 1 satellite in test status
  • 1+ billion civil/commercial GPS users now; perhaps several billion GPS devices worldwide
  • recent performance of GPS (global averages):
    •    best daily URE of 46.6 cm on 8 June 2013
    •    best weekly URE of 58.7 cm during week of 18 August 2014
    •    newer satellites typically perform better than older ones
    •    anticipate URE dropping to about 30 cm in a few years as more modern satellites come on line
  • 60-70 navigation data uploads to the satellites are performed each day; average of about two per satellite per day
  • IIFs:
    •  SV 3 and SVs 5-12 have improved rubidium clocks; one of the IIFs is running on a cesium clock
  • 14 SVs are currently broadcasting L2C (set healthy); 7 SVs are broadcasting L5 (set unhealthy)
  • CNAV:
    • Data uploads are currently being done about twice per week to each satellite; daily updates expected by December 2014
    • average UREs currently about 1.4 m (data ages quickly with few uploads per week); expect CNAV URE to be marginally better than LNAV (Legacy NAV) when daily uploads begin
  • Continued progress in bringing M-code on line; expect early use by 2017
  • GPS III:
    • satellites will use three improved rubidium clocks
    • although the program is behind schedule, SV 1 will be available for launch starting in January 2016
    • the Block 0 version of the OCX (Next Generation Operational Control System), currently under test, will be needed to support the GPS III satellites
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About the Author: Richard B. Langley

Richard B. Langley is a professor in the Department of Geodesy and Geomatics Engineering at the University of New Brunswick (UNB) in Fredericton, Canada, where he has been teaching and conducting research since 1981. He has a B.Sc. in applied physics from the University of Waterloo and a Ph.D. in experimental space science from York University, Toronto. He spent two years at MIT as a postdoctoral fellow, researching geodetic applications of lunar laser ranging and VLBI. For work in VLBI, he shared two NASA Group Achievement Awards. Professor Langley has worked extensively with the Global Positioning System. He has been active in the development of GPS error models since the early 1980s and is a co-author of the venerable “Guide to GPS Positioning” and a columnist and contributing editor of GPS World magazine. His research team is currently working on a number of GPS-related projects, including the study of atmospheric effects on wide-area augmentation systems, the adaptation of techniques for spaceborne GPS, and the development of GPS-based systems for machine control and deformation monitoring. Professor Langley is a collaborator in UNB’s Canadian High Arctic Ionospheric Network project and is the principal investigator for the GPS instrument on the Canadian CASSIOPE research satellite now in orbit. Professor Langley is a fellow of The Institute of Navigation (ION), the Royal Institute of Navigation, and the International Association of Geodesy. He shared the ION 2003 Burka Award with Don Kim and received the ION’s Johannes Kepler Award in 2007.