Seismic amplifier performance may be categorized broadly into AGC action, filtering, and distortion (including noise). Eight specifications can define the characteristics of each as follows:
AGC— 1. Steady-state AGC including “burst-out”, 2. AGC control vs frequency, 3. Dynamic AGC action, 4. AGC distortion effects;
Filtering— 5. Amplitude response, 6. Phase response;
Noise and 7. Pre-filter distortion;
Distortion—8. Internal amplifier noise.
These eight specifications allow a user to predict, and consequently allow for, amplifier action—both desirable and deleterious—in obtaining field records.
The author proposes that these specifications, coupled with the usual “external” specifications, be considered as a starting point for establishing a standardized method of specifying seismic amplifier characteristics similar to the SEG “Standard Methods of Specifying Performance” for magnetic recording.