What does NDGPS stand for in GPS technology?

NDGPS stands for National Differential GPS, which refers to a system that enhances the accuracy of GPS positioning. Differential GPS improves the precision of standard GPS signals by using a network of fixed ground-based reference stations. These reference stations calculate the difference between their known fixed positions and the positions calculated from the GPS signals. By broadcasting correction signals to nearby GPS receivers, NDGPS can significantly reduce the errors in the GPS measurements, typically to within a few centimeters.

This system is particularly important in applications where high accuracy is essential, such as in surveying, agriculture, and navigation. The inclusion of "National" highlights that this system is implemented and managed at a national level, emphasizing its wide-ranging usefulness across various regions and applications. The other options do not accurately reflect the established term used in GPS technology, which is specifically tied to differential corrections.