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Record Search Query: ServiceParameters>DATA ANALYSIS AND VISUALIZATION>GLOBAL POSITIONING SYSTEMS

NASA Global Differential GPS (GDGPS) System
Entry ID: NASA_GDGPS
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Summary
Abstract: Employing the largest global real-time tracking network, the Global Differential GPS (GDGPS) System tracks the GPS civil signals on the L1 and L2 frequencies. Highly redundant satellite coverage (25 fold, on average) ensures seamless and robust global coverage. The raw measurements are streamed via redundant communication paths to multiple GDGPS Operation Centers (GOC) (3 centers as of October 2006). At the GOC the data is processed by the award-winning software, Real Time GIPSY (RTG), to derive the real-time differential corrections to the GPS orbit and clock states, as well as many by-products and services. Our state-space approach to orbit determination ensures that all the products are globally and uniformly valid.

The fundamental latency of the system is ~5 seconds from reception of the navigation signal by the tracking receiver to the production and dissemination of the differential corrections and the other real-time by-products. Lower latency for certain products, such as integrity monitoring, is supported.

The data products are disseminated to customers through a variety of channels. Customers are encouraged to access multiple GOCs and use multiple communications channels to ensure end-to-end redundancy for mission-critical products and services. Supported channels include: internet, VPN over internet, T1, Frame Relay, modems, and satellite broadcast.

Extremely high reliability has been accomplished through an extremely high level of end-to-end redundancy, without any single point of failure. Innovative software ensures automatic fault detection and seamless failover between various redundant components of the system, resulting in uninterrupted service to customers.

[Summary provided by NASA.]

Related URL
Link: VIEW RELATED INFORMATION
Description: Applications of the NASA Global Differential GPS (GDGPS) System.
Service Citation
Originators: NASA JPL
Title: NASA Global Differential GPS (GDGPS) System
Provider: NASA JPL
URL: http://www.gdgps.net/
Science Keywords
AGRICULTURE >AGRICULTURAL AQUATIC SCIENCES   [Definition]
AGRICULTURE >AGRICULTURAL CHEMICALS   [Definition]
AGRICULTURE >AGRICULTURAL ENGINEERING   [Definition]
AGRICULTURE >AGRICULTURAL PLANT SCIENCE   [Definition]
AGRICULTURE >ANIMAL COMMODITIES   [Definition]
AGRICULTURE >ANIMAL SCIENCE   [Definition]
AGRICULTURE >FEED PRODUCTS   [Definition]
AGRICULTURE >FOOD SCIENCE   [Definition]
AGRICULTURE >FOREST SCIENCE   [Definition]
AGRICULTURE >PLANT COMMODITIES   [Definition]
AGRICULTURE >SOILS   [Definition]
BIOSPHERE >ECOLOGICAL DYNAMICS   [Definition]
BIOSPHERE >TERRESTRIAL ECOSYSTEMS   [Definition]
BIOSPHERE >VEGETATION   [Definition]
CRYOSPHERE >SEA ICE   [Definition]
CRYOSPHERE >SNOW/ICE   [Definition]
HUMAN DIMENSIONS >SOCIAL BEHAVIOR   [Definition]
HUMAN DIMENSIONS >BOUNDARIES   [Definition]
HUMAN DIMENSIONS >ECONOMIC RESOURCES   [Definition]
HUMAN DIMENSIONS >ENVIRONMENTAL IMPACTS   [Definition]
HUMAN DIMENSIONS >PUBLIC HEALTH   [Definition]
HUMAN DIMENSIONS >INFRASTRUCTURE   [Definition]
HUMAN DIMENSIONS >ENVIRONMENTAL GOVERNANCE/MANAGEMENT >LAND MANAGEMENT >LAND USE/LAND COVER CLASSIFICATION   [Definition]
HUMAN DIMENSIONS >NATURAL HAZARDS   [Definition]
HUMAN DIMENSIONS >POPULATION   [Definition]
TERRESTRIAL HYDROSPHERE >GROUND WATER   [Definition]
TERRESTRIAL HYDROSPHERE >SNOW/ICE   [Definition]
TERRESTRIAL HYDROSPHERE >SURFACE WATER   [Definition]
TERRESTRIAL HYDROSPHERE >WATER QUALITY/WATER CHEMISTRY   [Definition]
LAND SURFACE >EROSION/SEDIMENTATION   [Definition]
LAND SURFACE >GEOMORPHOLOGY   [Definition]
LAND SURFACE >LAND TEMPERATURE   [Definition]
LAND SURFACE >LAND USE/LAND COVER   [Definition]
LAND SURFACE >LANDSCAPE   [Definition]
LAND SURFACE >SOILS   [Definition]
LAND SURFACE >SURFACE RADIATIVE PROPERTIES   [Definition]
LAND SURFACE >TOPOGRAPHY   [Definition]
OCEANS >BATHYMETRY/SEAFLOOR TOPOGRAPHY   [Definition]
OCEANS >COASTAL PROCESSES   [Definition]
OCEANS >MARINE ENVIRONMENT MONITORING   [Definition]
OCEANS >MARINE GEOPHYSICS   [Definition]
OCEANS >MARINE SEDIMENTS   [Definition]
OCEANS >OCEAN ACOUSTICS   [Definition]
OCEANS >OCEAN CHEMISTRY   [Definition]
OCEANS >OCEAN CIRCULATION   [Definition]
OCEANS >OCEAN HEAT BUDGET   [Definition]
OCEANS >OCEAN OPTICS   [Definition]
OCEANS >OCEAN PRESSURE   [Definition]
OCEANS >OCEAN TEMPERATURE   [Definition]
OCEANS >OCEAN WAVES   [Definition]
OCEANS >OCEAN WINDS   [Definition]
OCEANS >SALINITY/DENSITY   [Definition]
OCEANS >SEA ICE   [Definition]
OCEANS >TIDES   [Definition]
OCEANS >WATER QUALITY   [Definition]
PALEOCLIMATE >ICE CORE RECORDS   [Definition]
PALEOCLIMATE >LAND RECORDS   [Definition]
PALEOCLIMATE >OCEAN/LAKE RECORDS   [Definition]
SPECTRAL/ENGINEERING >INFRARED WAVELENGTHS   [Definition]
SPECTRAL/ENGINEERING >MICROWAVE   [Definition]
SPECTRAL/ENGINEERING >PLATFORM CHARACTERISTICS   [Definition]
SPECTRAL/ENGINEERING >RADAR   [Definition]
SPECTRAL/ENGINEERING >SENSOR CHARACTERISTICS   [Definition]
SPECTRAL/ENGINEERING >ULTRAVIOLET WAVELENGTHS   [Definition]
SPECTRAL/ENGINEERING >VISIBLE WAVELENGTHS   [Definition]
SUN-EARTH INTERACTIONS >SOLAR ACTIVITY   [Definition]
SOLID EARTH >GEOCHEMISTRY   [Definition]
SOLID EARTH >GRAVITY/GRAVITATIONAL FIELD   [Definition]
SOLID EARTH >GEOMAGNETISM   [Definition]
SOLID EARTH >GEOMORPHIC LANDFORMS/PROCESSES   [Definition]
SOLID EARTH >GEOTHERMAL DYNAMICS   [Definition]
SOLID EARTH >EARTH GASES/LIQUIDS   [Definition]
SOLID EARTH >ROCKS/MINERALS/CRYSTALS   [Definition]
SOLID EARTH >TECTONICS >EARTHQUAKES   [Definition]
SOLID EARTH >TECTONICS   [Definition]
SOLID EARTH >TECTONICS >VOLCANIC ACTIVITY   [Definition]
OCEANS >SEA SURFACE TOPOGRAPHY   [Definition]
OCEANS >MARINE VOLCANISM   [Definition]
SPECTRAL/ENGINEERING >GAMMA RAY   [Definition]
SPECTRAL/ENGINEERING >RADIO WAVE   [Definition]
CRYOSPHERE >FROZEN GROUND   [Definition]
LAND SURFACE >FROZEN GROUND   [Definition]
OCEANS >AQUATIC SCIENCES   [Definition]
SPECTRAL/ENGINEERING >X-RAY   [Definition]
CRYOSPHERE >GLACIERS/ICE SHEETS   [Definition]
TERRESTRIAL HYDROSPHERE >GLACIERS/ICE SHEETS   [Definition]
HUMAN DIMENSIONS >HABITAT CONVERSION/FRAGMENTATION   [Definition]
PALEOCLIMATE >PALEOCLIMATE RECONSTRUCTIONS   [Definition]
SUN-EARTH INTERACTIONS >IONOSPHERE/MAGNETOSPHERE DYNAMICS   [Definition]
SUN-EARTH INTERACTIONS >SOLAR ENERGETIC PARTICLE FLUX   [Definition]
SUN-EARTH INTERACTIONS >SOLAR ENERGETIC PARTICLE PROPERTIES
BIOSPHERE >AQUATIC ECOSYSTEMS   [Definition]
SPECTRAL/ENGINEERING >LIDAR   [Definition]
ISO Topic Category
FARMING
BIOTA
BOUNDARIES
CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
ECONOMY
ELEVATION
ENVIRONMENT
GEOSCIENTIFIC INFORMATION
HEALTH
IMAGERY/BASE MAPS/EARTH COVER
INLAND WATERS
OCEANS
PLANNING CADASTRE
SOCIETY
STRUCTURE
TRANSPORTATION
UTILITIES/COMMUNICATIONS
Quality
QUALITY FACTORS

ANSI C for portability and maintainability.

Modularity. Highly modular code to support embedded as well as ground applications.

Reliability. Outstanding track record of continnuous operations.

Accuracy. All models are sub-cm accurate for the most demanding science applications.

Maintainability. Designed for operations by a third party and for team maintenance. Configuration control management.
Service Provider
Global Differential GPS, Jet Propulsion Laboratory, NASA

Service Provider Personnel
Name: YOAZ BAR-SEVER
Phone: 818-354-2665
Fax: 818-393-4965
Email: yoaz.e.bar-sever at nasa.gov
Contact Address:
Mail Stop 238-600
4800 Oak Grove Drive
City: Pasadena
Province or State: CA
Postal Code: 91109
Country: USA
Personnel
YOAZ BAR-SEVER
Role: TECHNICAL CONTACT
Phone: 818-354-2665
Fax: 818-393-4965
Email: yoaz.e.bar-sever at nasa.gov
Contact Address:
Mail Stop 238-600
4800 Oak Grove Drive
City: Pasadena
Province or State: CA
Postal Code: 91109
Country: USA

TYLER B. STEVENS
Role: SERF AUTHOR
Phone: (301) 614-6898
Fax: 301-614-5268
Email: Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA
Publications/References
Development of a Real-Time Single-Frequency Precise Point Positioning System and Test Results
Yang Gao and Kongzhe Chen
The University of Calgary
Describe the development of a real-time single-frequency PPP system
using the ireal-time GPS orbit and clock products from the JPL GDGPS System.
Report test results under road and marine conditions.
ION GNSS 2006, Fort Worth, TX, USA, Sept.2005.

StarFire: A Global SBAS for Sub-Decimeter Precise Point Positioning
Kevin Dixon
Navcom Technology Inc.
Describe the structure and performance of the Navcom differential system,
which is based partially on JPL's Real Time GIPSY (RTG) software, and on
the GDGPS tracking network.
ION GNSS 2006, Fort Worth, TX, USA, Sept.2005.

Real-Time Precise Point Positioning (PPP) Using Single Frequency Data
Kongzhe Chen and Yang Gao
The University of Calgary
Investigates PPP using single-frequency data and precise real-time
orbits and clocks while comparing ionospheric correction methods:
Klobuchar, GIM, GRAPHIC and ionospheric gradient estimation. Includes
both static and kinematic airborne positioning results, contrasting
the different modeling methods.
ION GNSS 2005, Long Beach, CA, USA, Sept.2005.

Performance Evaluation of Global Differential GPS (GDGPS) for Single Frequency C/A Code Receivers
Sundar Raman, and Lionel Garin
SiRF Technology, Inc.
Analyze the performance of GDGPS as a replacement for local differential GPS (LDGPS) for single-frequency users.
ION GNSS 2005, Long Beach, CA, USA, Sept.2005.

Real-time Kinematic Positioning with NASA's Global Differential GPS System
Kechine, M.O., C.C.J.M Tiberius, H. van der Marel
University of Delft, The Netherlands
Independent performance assessment of the GDGPS system for real-time
kinematic positioning performed at University of Delft, The Netherlands.
GNSS Conference, St. Petersburg, Russia, May 2004.

Real-Time Sub-cm Differential Orbit Determination of Two Low-Earth Orbiters with GPS Bias Fixing
Sien Wu and Yoaz Bar-Sever
Jet Propulsion Laboratory, California Institute of Technology
An effective technique for real-time differential orbit determination of two low Earth orbiters with GPS bias fixing is formulated. With this technique, only moderatequality GPS orbit and clock states (e.g., as available in real-time from the NASA Global Differential GPS System with 1020 cm accuracy) are needed to seed the process.
ION GNSS 2006, Fort Worth, TX, USA, Sept.2005.

The NASA Global Differential GPS System (GDGPS) and The TDRSS Augmentation Service for Satellites (TASS)
Yoaz Bar-Sever, Larry Young, Frank Stocklin, Paul Heffernan and John Rush
Jet Propulsion Laboratory, California Institute of Technology
Status of the NASA GDGPS System and the newly developed TDRSS
Augmentation Service for Satellites (TASS), with focus on space applications.
Presentation at the ESA 2nd Workshop on navigation equipment,
Noordwijk, The Netherlands, December 2004.

Real-Time Point Positioning Performance Evaluation of Single-Frequency
Receivers Using NASA's Global Differential GPS System
Muellerschoen, R., B. Iijima, R. Meyer, Y. Bar-Sever, E. Accad
Jet Propulsion Laboratory, California Institute of Technology
Techniques for precise real time positioning of single frequency users.
Accuracy assessment of real-time global ionospheric maps produced by
the GDGPS System.
ION GNSS Meeting, Long Beach, CA, September 2004.

Toward Decimeter-level Real-Time Orbit Determination:
a Demonstration Using the SAC-C and CHAMP Spacecraft
Reichert, A., T. Meehan, and T. Munson
Jet Propulsion Laboratory, California Institute of Technology
Demonstration of onboard, autonomous, real-time orbit determination
with JPL's Real Time GIPSY (RTG) software and analysis of the
orbit determination capabilities of the GDGPS System
ION GPS Meeting, Portland OR, September, 2002.

Demonstration of Decimeter-level Real-time Positioning of an Airborne Platform
M. Armatys, R. Muellerschoen, Y. Bar-Sever, R. Meyer
Jet Propulsion Laboratory, California Institute of Technology
Proceedings,ION NTM-2003, Anaheim, CA

Orbit Determination With NASA's High Accuracy Real-Time Global Differential GPS System
R. J. Muellerschoen, A. Reichert, D. Kuang, M. Heflin, W. I. Bertiger and Y. E. Bar-Sever
GPS orbits and clocks are computed in real-time with data from NASA's global GPS network. The accuracy of the GPS orbits and reference frame alignment to ITRF'97 is discussed. The dissemination of the global correction message is over the Internet, and a signal-in-space (SIS) is provided by America's Inmarsat satellite. The SIS will soon expand for global coverage with Inmarsat's ASPAC (Asia/Pacific) and EMEA (Europe/Africa) satellites yielding coverage over the entire globe between +/-75 degrees in latitude. The inherent latency in providing the corrections to the user through the geosynchronous satellites is shown to have little impact on true real-time positioning. Orbit determination, post-processed but filtered as if in real-time, of a low-Earth orbiter's GPS data using the real-time orbit and clock products will be presented. Anticipated plans call for uploading the code to a space-qualified receiver and performing orbit determination with the GPS differential global corrections as transmitted by the Inmarsat beams.
Proceedings of ION GPS-2001, Salt Lake City, UT, September 2001.

Results of an Internet-Based Dual-Frequency Global Differential GPS System
R. J. Muellerschoen, W. I. Bertiger and M. F. Lough
Observables from a global network of 18 GPS receivers are returned in real-time to JPL over the open Internet. Global GPS orbits accurate to 30-40 cms RSS and precise dual-frequency GPS clocks are computed in real-time with JPL's Real-Time Gipsy (RTG) software. Corrections to the broadcast orbits and clocks are communicated to the user over the open Internet via a TCP server. Tests of user positioning show real-time RMS accuracy of 8 cms RMS in horizontal and 20 cms RMS in the vertical.
Proceedings of IAIN World Congress, San Diego, CA, June 2000

An Internet-Based Global Differential GPS System, Initial Results
R. J. Muellerschoen, W. I. Bertiger, M. F. Lough, D. Stowers, D. Dong
Using a network of 15 global GPS receivers, GPS data is returning to JPL via the open Internet to determine the orbits and clocks of the GPS constellation in real-time. Corrections to the broadcast orbits and clocks are currently communicated in real-time to the user over the open Internet via a TCP server. Tests of user positioning show real-time RMS accuracy of ~10 cms RMS in horizontal and < 20 cms RMS in the vertical.
ION National Technical Meeting, Anaheim, CA, Jan, 2000

Flight Tests Demonstrate Sub 50 cms RMS Vertical WADGPS Positioning
Wide Area Differential GPS (WADGPS) positioning is performed in real-time during NASA's DC-8 AirSAR flights. R. J. Muellerschoen, W. I. Bertiger and M. L. Whitehead
The goal of the experiment is to demonstrate absolute positioning in earth-fixed coordinates to better than one meter in all components in real-time. Results show dual-frequency real-time RMS (root-mean-square) accuracy in the vertical to be 50-60 cms with an RMS horizontal accuracy of better than 40 cms.
Proceedings of ION GPS-99, Nashville, Tenn., September 1999.

Incorporation of Orbital Dynamics to Improve Wide-Area Differential GPS
J. Ceva, B. Parkinson, W. I. Bertiger, R. J. Muellerschoen, and T. P. Yunck
Navigation, Summer 1997, Vol. 44, No. 2, pg. 171-180
Invited Contribution to Institute of Navigation "Red Books," Global Positioning System: Papers Published in Navigation, Vol. IV, 1999.

A Real-Time Wide Area Differential GPS System
W. I. Bertiger, Y. E. Bar-Sever, B. J. Haines, B. A. Iijima, S. M. Lichten, U. J. Lindqwister, A. J. Mannucci, R. J. Muellerschoen, T. N. Munson, A. W. Moore, L. J. Romans, B. D. Wilson, S. C. Wu, T. P. Yunck, G. Piesinger, and M. L. Whitehead
Invited Contribution to Institute of Navigation "Red Books," Global Positioning System: Papers Published in Navigation, Vol. IV, 1999
Navigation: Journal of the Institute of Navigation, Vol. 44, No. 4, 1998, pgs. 433-447

A Close Look at Satloc's Real-Time WADGPS System GPS Solutions
M. L. Whitehead, G. Penno, W. J. Feller, I. C. Messinger, W. I. Bertiger, R. J. Muellerschoen, and B. A. Iijima
GPS Solutions, Vol 2, No. 2, John Wiley & Sons, Inc., 1998. Invited Paper

Precise Real-Time Positioning Using Wide Area Differential GPS, Field Tests
W. I. Bertiger, Y. E. Bar-Sever, T. J. Borden, B. A. Iijima, R. J. Muellerschoen, T. N. Munson, A. W. Moore, L. J. Romans, S. C. Wu, M. L. Whitehead, W. Feller, G. Penno
Proceedings of the ION National Tech. Meeting, Long Beach, CA, Jan. 1998

Concept for a Wide-Area GPS Navigation System
W. I. Bertiger, S. M. Lichten, A. J. Mannucci, R. J. Muellerschoen, S. C. Wu, and T. P. Yunck
NASA Tech Brief, NPO-19625, June, 1997.

A Prototype Real-Time Wide Area Differential GPS System
W. I. Bertiger, Y. E. Bar-Sever, B. J. Haines, B. A. Iijima, S. M. Lichten, U. J. Lindqwister, A. J. Mannucci, R. J. Muellerschoen, T. N. Munson, A. W. Moore, L. J. Romans, B. D. Wilson, S. C. Wu, T. P. Yunck, G. Piesinger, and M. L. Whitehead
Proceedings of the ION National Technical Meeting, Santa Monica, CA, Jan. 1997.

Orbit and Troposphere Results of a Real-Time Prototype WADGPS System
R. J. Muellerschoen, W. I. Bertiger, and L. J. Romans,
Proceedings of the ION National Tech. Meeting, Santa Monica, CA, Jan. 1997.

A Prototype WADGPS System for Real Time Sub-Meter Positioning Worldwide
T. P. Yunck, Y. E. Bar-Sever, B. A. Iijima, S. M. Lichten, U. J. Lindqwister, A. J. Mannucci, R. J. Muellerschoen, T. N. Munson, L. J. Romans, S. C. Wu
Proceedings of the 9th International Technical Meeting of The Institute of Navigation, Kansas City, MO, September 17-20, 1996.
Creation and Review Dates
SERF Creation Date: 2009-06-16
SERF Last Revision Date: 2009-09-23
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