What Is a GPS Augmentation?
A GPS augmentation is any system that aids GPS by providing accuracy, integrity, availability, or any other improvement to positioning, navigation, and timing that is not inherently part of GPS itself.
A wide range of different augmentation systems have been developed by both the public and private sectors.
Publicly Available GPS Augmentation Systems
To meet specific requirements, the U.S. government has fielded a number of publicly available GPS augmentation systems, including (but not limited to) the following systems.
WAAS, a regional space-based augmentation system (SBAS) operated by the Federal Aviation Administration (FAA), supports aircraft navigation across North America.
Although designed primarily for aviation users, WAAS is widely available in receivers used by other positioning, navigation, and timing communities.
FAA is committed to providing WAAS service at the performance levels specified in the GPS WAAS Performance Standard. FAA is improving WAAS to take advantage of the future GPS safety-of-life signal to provide even better performance.
The WAAS service is interoperable with other regional SBAS services, including those operated by Japan (MSAS), Europe (EGNOS), and India (GAGAN).
More Information
- WAAS Page (faa.gov)
- WAAS Performance Data (faa.gov) -- live coverage maps, etc.
- GPS WAAS Performance Standard
The U.S. CORS network, managed by the National Oceanic and Atmospheric Administration, archives and distributes GPS data for precise positioning tied to the National Spatial Reference System.
Over 200 private, public, and academic organizations contribute data from almost 2,000 GPS tracking stations to CORS.
The Online Positioning User Service (OPUS) offers free post-processing of GPS data sets to the centimeter level using CORS information. CORS is also being modernized to support real-time users.
More Information
- CORS Homepage (noaa.gov)
- OPUS (noaa.gov)
- National Spatial Reference System (noaa.gov)
The GDGPS System is a real-time GNSS monitoring and augmentation system, developed, managed, and operated by the NASA Jet Propulsion Laboratory (JPL). GDGPS uses multiple network sources, relying primarily on the 60+ sites of NASA’s Global GNSS Network (GGN) (part of the NASA Space Geodesy Program), GDGPS owned and operated sites (19 sites fielded, with approximately 12 operating at any one time), and publicly available International GNSS Service (IGS) data from 100+ sites operating in real-time.
Operational since 2000, GDGPS provides real-time assisted GNSS (A-GNSS) products to support positioning and orbit determination, as well as civil-signal monitoring, situational assessment, natural hazard monitoring, ionospheric monitoring and remote-sensing applications. GDGPS also provides information on integrity and quality of GPS and other GNSS broadcast signals.
More Information
- GDGPS System (jpl.nasa.gov)
The International GNSS Service (IGS), one of the services of the International Association of Geodesy, provides on an openly available basis the highest-quality GNSS data, products, and services in support of the terrestrial reference frame, Earth observation and research, Positioning, Navigation and Timing (PNT), and a plethora of other applications that benefit the scientific community and society at large.
The foundation of the IGS is the global IGS Network, comprising over 530 permanent and continuously operating stations of geodetic quality in 100+ countries and regions. These stations track multi-GNSS signals from GPS, GLONASS, Galileo, BDS, QZSS, NavIC, as well as various space-based augmentation systems (SBAS). The IGS Real-Time Service allows access to the subset of stations able to transmit their data in real-time. IGS Products, derived from IGS Network data and available at a variety of latencies, include notably orbits and clocks, differential biases, ionospheric and tropospheric corrections, and reference frame parameters.
At the heart of the IGS is a strong culture of sharing expertise, infrastructure, and other resources for the purpose of encouraging global best practices for developing and delivering the highest possible quality GNSS data and products worldwide. Individuals and institutions interested in contributing to, participating to, or simply staying informed about the IGS' efforts are encouraged to subscribe to the IGS Mailing List(s), to apply to become IGS Associate Members, or to get in touch with relevant IGS Components.
More Information
- IGS Portal (igs.org)
- IGS Network (igs.org)
- IGS Real-Time Service (igs.org)
- IGS Products (igs.org)
- IGS Mailing List(s) (igs.org)
- Applying to become an IGS Associate Member (igs.org)
- Getting in touch with relevant IGS Components (igs.org)
NDGPS was a ground-based augmentation system that provided increased accuracy and integrity of GPS information to users on U.S. waterways.
As of June 30, 2020, all NDGPS service has been discontinued in accordance with the NDGPS Federal Register Notice USCG-2018-0133. With the rollout of the new GPS III satellites combined with the permanent termination of Selective Availability, DGPS is no longer deemed a necessary augmentation for close harbor approach.
There are many other GPS augmentation systems available worldwide, both government and commercial. These systems use differential, static, or real-time techniques.
There are also systems that augment other global navigation satellite systems. The United States is cooperating with many other nations to ensure the interoperability of international augmentation systems with GPS and U.S. GPS augmentations.