Differential GPS

GPS
Title	Differential GPS
Edited by	GMV
Level	Basic
Year of Publication	2011

Differential GPS (DGPS) is a kind of GNSS Augmentation system based on an enhancement to primary GPS constellation information by the use of a network of ground-based reference stations which enable the broadcasting of differential information to the user – also named rover – to improve the accuracy of his position – the integrity is not assured.

The Differential GNSS techniques and systems are explained in detail in the articles:

• Differential GNSS (DGNSS).
• Real Time Kinematics (RTK).
• Wide Area RTK (WARTK).

The case of DGPS is the same as DGNSS but using only measurements from the GPS constellation.

The DGPS term can also refer to specific implementations using DGNSS technique. It is often used to refer specifically to systems that re-broadcast the corrections from ground-based short-range transmitters, such as it occurs in maritime domain. Examples of DGPS systems are explained hereafter.

NATIONWIDE DIFFERENTIAL GPS SYSTEM (NDGPS)

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.

U.S. DGPS COVERAGE

GLOBAL DIFFERENTIAL GPS (GDGPS)

GDGPS is a high accuracy GPS augmentation system developed by the NASA Jet Propulsion Laboratory (JPL) to support the real-time positioning, timing, and determination requirements of NASA science missions.

Employing a large ground network of real-time reference receivers, innovative network architecture, and real-time data processing software, the GDGPS System provides sub-decimeter (<10 cm) positioning accuracy and sub-nanosecond time transfer accuracy anywhere in the world, on the ground, in the air, and in space, independent of local infrastructure.

A complete array of real-time GNSS state information, environmental data, and ancillary products are available in support of the GNSS Augmentation operations, Assisted GNSS (A-GNSS) services, situational assessment, and environmental monitoring - globally, uniformly, accurately, and reliably.

Full services are available for GPS, GLONASS, BeiDou, Galileo, QZSS, and NAVIC.

GDGPS has been providing high reliability position, navigation, and timing data services to industry and government operations since 2000. The GDGPS navigation technology underlie major global infrastructure, including the Wide Area Augmentation System (WAAS), and the next generation GPS Operational Control Segment (OCX).