Which method ignores satellites below a certain elevation to improve GPS accuracy?

Differential GPS (DGPS) enhances the accuracy of GPS positioning by using a network of fixed ground-based reference stations. These stations compute the difference between the precise location (as known from a survey point) and the location reported by the GPS satellites. By broadcasting this correction data to nearby GPS receivers, DGPS significantly reduces errors caused by atmospheric conditions, satellite clock discrepancies, and other inaccuracies.

In terms of ignoring satellites below a certain elevation, DGPS can improve accuracy because lower-elevation satellites are more susceptible to interference from buildings, vegetation, or other obstacles. By filtering out these satellites, the system relies on higher-elevation satellites that provide more reliable signals, thus improving positioning accuracy.

The other methods listed, such as Static GPS, Real-Time Kinematic (RTK), and Averaging GPS, have different operational characteristics and use cases that do not inherently prioritize satellite elevation as a factor in accuracy enhancement in the same way that DGPS does.