What is the name of the system used to control the increase in amplitude of an electrical signal from input to output, commonly used in seismic processing?

• A. Automatic Gain Control
• B. Peak Limiter
• C. Signal Amplifier
• D. Gain Stabilizer

Answer: (A)

Automatic gain control is a system that dynamically adjusts amplification so the output stays within a target range. It senses the signal level and increases gain when the input is weak or reduces gain when the input is strong, rather than applying a fixed amount of boost. In seismic processing, this helps balance amplitudes across traces and over time, compensating for variations due to geometric spreading, attenuation, and differing source-receiver geometries. This makes weaker reflections more visible and prevents strong events from dominating the display, aiding interpretation. A peak limiter clamps peaks to a set threshold and can distort spectral content, a plain signal amplifier raises everything by a fixed amount without adapting to the signal level, and gain stabilizer isn’t a standard term for this purpose.