How does Differential GPS (DGPS) improve GPS accuracy?

Differential GPS (DGPS) enhances GPS accuracy primarily by measuring errors from known locations. This process involves a network of fixed ground-based reference stations that have precisely known positions. These stations continuously monitor the GPS signals they receive and calculate the deviation between their known location and the location derived from the GPS signals. By determining the error, these stations can provide real-time corrections to the positioning data received by moving receivers.

The improved accuracy comes from the fact that the corrections account for various errors that can affect GPS signals, such as atmospheric conditions and signal multipath, which can distort the GPS readings. As a result, when a GPS receiver nearby receives the corrections from a reference station, it can adjust its own positioning data accordingly, leading to significantly enhanced accuracy over standard GPS systems alone.

In summary, DGPS leverages the known positions of reference stations to compute errors in GPS signal reception and apply corrections, thus providing a more accurate location estimate.