What is Automatic Gain Control (AGC) in radar and how does it affect detection?

• A. AGC automatically adjusts receiver gain to keep signal levels within a usable range; helps maintain consistent target detection across scenes.
• B. AGC increases transmitter power to targets automatically.
• C. AGC reduces display update rate.
• D. AGC removes weather clutter.

Answer: (A)

Automatic Gain Control in radar is the mechanism that automatically varies the receiver’s gain so that the strength of the incoming echoes stays within the receiver’s usable range. In a radar scene, returns come from targets at different ranges and with different reflectivity, plus clutter and noise. If gain isn’t adjusted, strong close targets could saturate the receiver and wash out weak distant targets, or weak targets could disappear into noise. AGC boosts gain when the signal is weak and reduces gain when the signal is strong, keeping the signal level entering the detector near an optimal value. This helps maintain consistent detection performance across the scene and keeps the display and decision thresholds from shifting as conditions change. It’s not about increasing transmitter power, it doesn’t change how often the display updates, and it doesn’t remove weather clutter—that’s handled by other clutter suppression techniques.