Subelement C: Receiving Systems – 10 Key Topics – 10 Exam Questions – 4 Drawings— Topic 25: Sea Clutter - STC
Question 8-25C4
Element 8 (RADAR)Sea clutter on the RADAR scope cannot be effectively reduced using front panel controls. What circuit would you suspect is faulty?
Explanation
Sea clutter is strong, short-range reflections from waves. The Sensitivity Time Control (STC) circuit, also known as Swept Gain, is specifically designed to combat this by automatically reducing the receiver's gain immediately after the transmitter pulse, then gradually increasing it over a short time. This prevents strong close-range echoes from saturating the display while preserving weaker, more distant targets. If the STC circuit is faulty, it won't properly attenuate these strong, close-in sea reflections, making them appear excessively bright and unmanageable by normal front panel gain controls.
The False Target Eliminator (FTE) deals with spurious targets from side lobes or multiple reflections. The Fast Time Constant (FTC) circuit is used to suppress rain clutter or distributed noise, not primarily sea clutter. The Intermediate Frequency (IF) circuit provides overall amplification and filtering, and while crucial, a fault there would likely cause broader reception issues rather than specific, unmanageable sea clutter.