Which processing technique helps suppress stationary returns to emphasize moving targets?

• A. Windowing
• B. CFAR
• C. Calibration
• D. MTI

Answer: (D)

MTI, or Moving Target Indicator, is designed to make moving targets stand out by suppressing stationary clutter. The idea is that stationary objects reflect echoes that don’t change from one radar pulse to the next, so when the processor compares successive echoes, these zero-Doppler components cancel out. Moving targets, on the other hand, have a Doppler shift because they change position relative to the radar between pulses, so their returns survive the comparison and appear clearly.

In practice, MTI applies a temporal filter across pulses (often a differencing or high-pass filter). A simple version subtracts the previous pulse’s echo from the current one, canceling stationary clutter while preserving moving targets. More advanced MTI uses multiple taps to improve clutter rejection, though it can introduce velocity blind spots if not carefully configured.

Windowing, calibration, and CFAR serve different purposes—windowing shapes spectral leakage, calibration corrects system biases, and CFAR sets adaptive detection thresholds. None of these specifically target suppression of stationary returns like MTI does.