What are sea clutter and weather clutter, and how are they mitigated on radar?

• A. Sea clutter are returns from waves; weather clutter from precipitation; mitigated by MTI, clutter maps, adaptive thresholds, gain control, and filtering.
• B. Sea clutter are returns from ships; weather clutter is wind noise; mitigated by increasing transmitter power.
• C. Sea clutter is reflections from land; weather clutter is sun glare; mitigated by shielding.
• D. Sea clutter and weather clutter cannot be mitigated.

Answer: (A)

Sea clutter and weather clutter are two common radar nuisances that can hide real targets. Sea clutter comes from the rough ocean surface—the waves reflect radar energy and produce strong, extended echoes that can look like targets. Weather clutter comes from precipitation such as rain or snow—the echoes from falling droplets can fill large portions of the display and overwhelm real objects.

The best way to handle both is to apply a mix of processing techniques designed to separate true targets from clutter. Moving Target Indication (MTI) works by comparing successive radar returns to suppress echoes that don’t move much between scans, which reduces the dominance of slow or stationary clutter like sea ripples. Clutter maps use a prior understanding of where clutter tends to appear, so the system can anticipate and subtract or suppress those echoes in those regions. Adaptive thresholds adjust the detection level based on the current clutter environment, helping to keep false alarms down when clutter is high and still detect targets when clutter is low. Gain control helps keep strong clutter returns from saturating the receiver, preserving dynamic range for weaker targets. Filtering, including temporal and Doppler-based filtering, further separates moving targets from clutter by exploiting differences in their motion or spectral characteristics.

These approaches address both types of clutter effectively. Increasing transmitter power, by contrast, is not a clutter mitigation method and can worsen receiver saturation and overall detection performance.