What is the primary purpose of Mode 5 for the AN/MPQ-64A3 Sentinel radar?

The primary purpose of Mode 5 for the AN/MPQ-64A3 Sentinel radar is to aid in positive identification and preventing fratricide. Mode 5 refers to a system that improves the Identification Friend or Foe (IFF) capability of the radar, allowing it to distinctly recognize friendly aircraft from potential threats. This is crucial in combat scenarios where multiple aircraft may be operating in the same airspace, as it minimizes the risk of mistakenly targeting friendly forces.

By ensuring accurate identification, Mode 5 enhances situational awareness for operators and supports effective air defense operations. This capability is essential not only for the safety of friendly forces but also for maximizing the effectiveness of air defense systems in a joint operating environment.

The other choices focus on different functions unrelated to the primary role of Mode 5. For instance, increasing the radar's rotation speed or improving radar range detection are more related to performance enhancements rather than identification and safety. Similarly, enhancing signal encryption is vital for secure communications but does not directly tie into the identification of aerial threats. Thus, the correct answer highlights the critical role of Mode 5 in preventing friendly fire incidents and ensuring robust air defense coordination.