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System Description - Software


The GDGPS System is driven by a powerful software set, developed completely in-house at JPL, and possessing many unique features and capabilities. The C++ software evolved from one of the world's leading GPS data processing and analysis software packages, JPL's GIPSY-OASIS and its real-time version RTG (Real Time GIPSY). The GDGPS software elements have accumulated a remarkable track record of accomplishments, including:

Used as prototype for the FAA's Wide Area Augmentation System (WAAS)

Awarded NASA Software of the Year 2000

Flew in space, embedded in a JPL Blackjack GPS receiver, performing real-time onboard orbit determination, 2002

Inducted into the Space Technology Hall of Fame, 2004

The current version of the software, entitled RTGx, will be the navigation software for the Next Generation GPS Operational Control Segment (OCX), and was developed under the strict quality assurance processes as appropriate for its critical mission at the heart of the world's most important infrastructure.


Complete automation. End-to-end automatic operations.

Complete positioning system. The software handles all aspects of a complete real time global positioning system, including GNSS orbit determination and simultaneous network positioning. Embedded, the software performs user positioning and orbit determination. Supports real-time applications as well as post-processing applications. Simulations capability.

Highly portable. The software is regularly tested on multiple flavors of Linux. Various positioning modules have been ported to several embedded real-time environments, including flight receivers.

Versatile. Works with many types of popular geodetic receivers. Flexible adaptation layer makes it easy to accommodate new receiver types.

Visual aids. Real time graphic display of performance using network monitoring tools and internal quality control.


Object Oriented C++ and Python for portability and maintainability.

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

Reliability. Outstanding track record of continuous 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.


  • Parallelized architecture (MPI) enables real-time solutions to massive estimation problems, e.g., multiple GNSS constellations.

  • State-space architecture guarantees seamless global uniformity of the differential corrections

  • Innovative use of the internet to achieve robustness through redundancy

  • Unique satellite dynamics and signal models developed in house at JPL

  • Efficient GNSS data compression

  • Innovative system for end-to-end redundant operations provides high reliability

  • Uniquely flexible filter design allows any parameter to have stochastic attributes

  • Capable of adding satellites/receivers on the fly

  • Unique dynamics integrator supports very high orbit modeling accuracy

  • Tropospheric delay model and stochastic estimation capability for users or reference sites

  • Exploit full information content of phase data

  • Real time playback

  • Software protected by multiple U.S. and non-U.S. patents

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