What is the primary purpose of a moving target indicator (MTI)?

The primary purpose of a moving target indicator (MTI) is indeed to produce an output that identifies moving targets while filtering out stationary ones. MTI radar systems are designed to differentiate between objects that are in motion and those that are not, which is crucial in applications like air traffic control and military surveillance. By focusing on changes in the Doppler frequency of reflected signals, an MTI can effectively highlight and track moving entities, thereby enhancing situational awareness.

In contrast, other options do not align with the core function of MTI. For example, detecting altitude changes pertains more to altitude measurement instruments than the detection of movement. Similarly, producing an output for identifying stationary targets conflicts with the MTI's design purpose, which is explicitly aimed at identifying motion rather than stasis. Amplifying weak signals refers to the general capabilities of radar systems rather than the specific role of an MTI, which is about detecting movement rather than signal strength. Each of these options highlights concepts relevant to radar technology but does not encapsulate the primary focus of a moving target indicator.