Which system uses orbital satellites to relay data for communication?

The correct answer is SATCOMs, which stands for Satellite Communications systems. These systems utilize orbital satellites to relay data and facilitate communication over vast distances, providing a reliable means of transmitting information, especially in environments where traditional communication infrastructure may be insufficient or unavailable. SATCOM technology is essential for both military and civilian applications, including voice communication, data transmission, and video conferencing, enabling connectivity across remote and geographically challenging locations.

In contrast, the other options are less reliant on satellite technology. For instance, STU IIIs, which are secure telephone units, primarily use traditional telecommunication links for secure voice and data communications, rather than satellite relays. Radio systems typically operate within specific frequencies and ranges using terrestrial stations for communication. Local Area Networks (LANs) are limited to specific geographical areas and utilize wired or wireless technologies for local communications without the involvement of satellites. Therefore, SATCOMs are distinctly characterized by their satellite-based architecture for global communication needs.