Which mechanism reduces the gain of the IF preamplifier stage immediately after the transmitter fires?

• A. STC (Sensitivity Time Control)
• B. AGC (Automatic Gain Control)
• C. MGC (Manual Gain Control)
• D. PGC (Pulse Gain Control)

Answer: (A)

Sensitivity Time Control is a time-dependent gain adjustment applied right after the transmitter fires. It lowers the receiver’s gain during the very early part of the return window to prevent saturation from strong near-field echoes and transmitter leakage, protecting the IF preamplifier. As time passes, the attenuation eases and the gain returns toward normal, so you can detect weaker, farther echoes. This immediate, time-based suppression is what makes STC the best fit for reducing gain right after a pulse.

Automatic Gain Control would react to signal level over a longer period and could blur the boundary between near and far echoes, which isn’t desirable for pulsed radar timing. Manual Gain Control requires user action and isn’t automatic. Pulse Gain Control isn’t the standard mechanism used for protecting the receiver in that immediate post-pulse interval.