DGNSS

DGNSS, or differential Global Navigation Satellite System, is a method of improving GNSS positioning by using corrections derived from one or more reference receivers at known locations. The reference receivers monitor GNSS signals from satellites and compare measured pseudorange and carrier-phase values with the true ranges; the resulting differences, or corrections, are transmitted to user receivers to reduce common-mode errors such as satellite orbit and clock errors, as well as some atmospheric biases.

In real-time operations, corrections are broadcast via radio links, cellular networks, or satellite-based augmentation systems, and are applied by the user receiver to compute a more accurate position. In post-processed DGNSS, raw observations recorded by distant receivers are reprocessed together to produce a precise solution after the fact.

Two common forms are real-time DGPS using local or networked reference stations and SBAS, which provide wide-area corrections (e.g., WAAS in the US, EGNOS in Europe) via geostationary satellites. The combination can improve horizontal accuracy from typical standalone GNSS levels of several meters to sub-meter or decimeter levels in well-covered networks; carrier-phase methods such as RTK can achieve centimeter-level accuracy over short baselines.

Applications include land surveying, marine navigation, precision agriculture, construction, and geodesy. Limitations include reliance on a dense network of reference stations, communication links, and potential degradation of corrections due to terrain, obstructions, or ionospheric conditions.