Proximity Fuze uses what to measure time between transmission and reception of a radar wave?

• A. Infrared sensor.
• B. Acoustic sensor.
• C. Uses Doppler radar to measure time between transmission and reception of a radar wave.
• D. GPS timing.

Answer: (C)

Proximity fuzes detect how close a target is by using radar to sense the echo that returns after a pulse is sent. The fuse emits a radar signal and watches for its return; the time it takes for that echo to come back corresponds to the distance to the target, allowing the fuse to trigger at the right range. Doppler radar is used here because it can efficiently extract the return signal and distinguish true echoes from clutter by using the Doppler shift caused by relative motion, helping verify a valid target and maintain reliable range sensing. Infrared sensors detect heat, not radar echoes; acoustic sensors rely on sound waves, which aren’t practical for this purpose; GPS timing isn’t used to measure the radar echo timing inside a proximity fuse.