How do ADS-B systems determine an aircraft's position?

The correct understanding of how ADS-B (Automatic Dependent Surveillance–Broadcast) systems determine an aircraft's position is rooted in their reliance on satellite navigation, specifically Global Navigation Satellite System (GNSS) technology. ADS-B uses signals from satellites to accurately calculate the aircraft's latitude, longitude, altitude, and velocity. This information is periodically broadcast to ground stations and other aircraft, enhancing situational awareness and improving air traffic management.

Other options do not accurately represent how ADS-B operates. For instance, while radio communication with air traffic control is essential in aviation, it does not directly provide the positional data for ADS-B systems. Similarly, relying on pilot input for coordinates is not a part of how ADS-B determines position, as automation is a key feature of the system. Ground radar systems, while still in use for air traffic control, do not play a role in the ADS-B position determination process, which is fundamentally dependent on satellite-based navigation.