What is a velocity gate in radar tracking?

• A. A velocity gate determines the direction of a target's motion to predict future bearing.
• B. A velocity gate sets the maximum reporting rate for target updates to reduce bandwidth.
• C. A velocity gate is a physical aperture in front of the antenna to filter by speed.
• D. A velocity gate constrains accepted target speeds to a defined range; used to filter out improbable detections.

Answer: (D)

In radar tracking, a velocity gate is a filter that constrains accepted target speeds to a defined range and is used to filter out improbable detections. The tracker predicts the target’s velocity and then checks each candidate detection’s speed against that prediction within a tolerance band. If the detected speed falls inside the gate, it’s considered a valid association with the track; if it’s outside, that detection is rejected as unlikely. This helps remove clutter like birds, weather echoes, or random noise that don’t match the expected motion of the target. It isn’t a physical device or aperture, it doesn’t control how fast updates are sent, and it doesn’t alone determine the direction of motion—those aspects come from other parts of the tracking process.