DGNSS Systems

Fundamentals
Title	DGNSS Systems
Author(s)	GMV
Level	Basic
Year of Publication	2011

Among the different GNSS Augmentation systems, the DGNSS system are widely used by navigation users. Nowadays, almost all commercial GPS units, even hand-held units, now offer DGPS data inputs. To some degree, a form of DGPS is now a natural part of most GPS operations.

DGNSS Systems

There are many operational systems in use throughout the world, according to the US Coast Guard, 47 countries operate systems similar to the US NDGPS (Nationwide Differential Global Positioning System). Next, there are some significant examples of DGNSS systems by country:

• United States

The first GNSS system was developed by the United States Coast Guard, called firstly DGPS and that has evolved to the US NDGPS (Nationwide Differential Global Positioning System). They 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

Australia runs two DGPS systems: one is mainly for marine navigation, run by Australian Maritime Safety Authority, broadcasting its signal on the longwave band; the other is used for land surveys and land navigation, and has corrections broadcast on the Commercial FM radio band.

• Canada

The Canadian system is similar to the US system and is primarily for maritime usage covering the Atlantic and Pacific coast as well as the Great Lakes and Saint Lawrence Seaway. It has been developed by the Canadian Coast Guard

Other DGNSS Systems

There are other DGNSS techniques used by high-precision navigation/surveying applications, based on the use of carrier phase measurements. These are the cases of the Real Time Kinematic (RTK) and the Wide Area RTK (WARTK), where the differential GPS measurements are computed in real-time by specific GPS receivers if they receive a correction signal using a separate radio receiver.