What type of signal does differential GPS (DGPS) use for improved accuracy?

Differential GPS (DGPS) enhances the accuracy of standard GPS signals by utilizing corrections from a network of ground-based reference stations. These reference stations calculate the difference between their known fixed positions and the positions determined by satellite data. The corrections derived from these differences are then transmitted to GPS receivers in the area, allowing them to adjust their calculated positions accordingly.

The use of ground-based reference stations is crucial for achieving greater precision, particularly in areas where standard GPS signals may be affected by atmospheric conditions, obstructions, or multipath effects. This correction process results in significantly improved accuracy compared to using satellite signals alone.

In contrast, signals from space satellites, only GPS satellite signals, and barometric data from onboard sensors do not inherently provide the level of refinement necessary for the enhanced positioning accuracy that DGPS offers. While satellite signals are essential for global positioning, they do not account for the local environmental impacts and therefore can lead to errors that DGPS effectively mitigates using ground-based corrections.