What is the primary function of GNSS Receivers?

• A. Conducting aerial triangulation
• B. Terrestrial-based surveying methods
• C. Satellite-based positioning
• D. Feature extraction from aerial photographs

Answer: (C)

GNSS receivers are built to determine location and time by using signals from satellites. Their main function is satellite-based positioning: by receiving time signals from multiple satellites and comparing them to the receiver’s clock, they compute the user’s 3D position (latitude, longitude, altitude) and precise time. Typically at least four satellites are needed to resolve the position and clock error, enabling accurate real-time or post-processed positioning for navigation, mapping, or surveying tasks.

The other options describe different methods: aerial triangulation relies on photogrammetric measurements from overlapping photos; terrestrial-based surveying uses ground-based techniques without satellite signals; and feature extraction from aerial photographs involves interpreting imagery rather than determining coordinates from satellite signals.