What are the two types of authorized GPS used by the Coast Guard?

• A. NDGPS and WASS
• B. GPS and GLONASS
• C. WAAS and EGNOS
• D. NAVSTAR and Galileo

Answer: (A)

Understanding how GPS accuracy and reliability are maintained is key. Nationwide Differential GPS builds on standard GPS by using a network of ground reference stations that measure satellite signals and broadcast corrections to receivers across the country. These corrections improve position accuracy and reliability over a wide area, which is essential for maritime operations that depend on consistent, precise fixes.

The Wide Area Augmentation System adds another layer by sending correction and integrity data from geostationary satellites. This augmentation enhances GPS performance over large regions, providing higher accuracy and alerting you to any satellite or signal issues in real time.

Together, these augmentation methods are the ones the Coast Guard references for authorized GPS use, combining broad-area differential corrections with real-time integrity information to support safe and precise navigation at sea. Other options involve different satellite systems or augmentation programs, but they’re not the two types specified as Coast Guard authorized in this context.