Differential GNSS

Fundamentals
Title	Differential GNSS
Author(s)	GMV
Level	Basic
Year of Publication	2011

Differential GNSS (DGNSS) is a kind of GNSS Augmentation system based on an enhancement to primary GNSS constellation(s) 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. There are several DGNSS techniques, such as the classical DGNSS (or DGPS), the Real Time Kinematic (RTK) and the Wide Area RTK (WARTK).

Differential GNSS

Wiki:

Differential GNSS (DGNSS) is an enhancement to a primary GNSS system, such as GPS, that uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. These stations broadcast the difference between the measured satellite pseudoranges and actual (internally computed) pseudoranges, and receiver stations may correct their pseudoranges by the same amount. The correction signal is typically broadcast over UHF radio modem.

The term can refer both to the generalized technique as well as specific implementations using it. It is often used to refer specifically to systems that re-broadcast the corrections from ground-based transmitters of shorter range.

Systems operating:

For instance, the [ref United States Coast Guard] and Canadian Coast Guard run one such system in the US and Canada on the longwave radio frequencies between 285 kHz and 325 kHz. These frequencies are commonly used for marine radio, and are broadcast near major waterways and harbors.

Australia runs two DGPS systems: one is mainly for marine navigation, broadcasting its signal on the longwave band;[1] the other is used for land surveys and land navigation, and has corrections broadcast on the Commercial FM radio band.

Two systems for air navigation and precision landing of aircraft, in Australia, will eventually replace the Instrument Landing System. Both utilise DGPS techniques and are called the Ground Based Augmentation System and Ground based Regional Augmentation Systems. Both of these systems broadcast corrections via the aviation VHF band.