Geophysical data acquisition, processing and interpretation - Geophysics for the Mineral Exploration Geoscientist - page 43

Impulses
(spikes)

Smooth, periodic
variable amplitude

Smooth, broad,
mono-polar

Random Step Gradient

Input

High-pass filter

Vertical scale preserved

Low-pass filter

Vertical scale preserved

Band-pass filter

Vertical scale preserved

Median filter

Vertical scale preserved

Mean (moving average) filter

Vertical scale preserved

Terracing filter

Vertical scale preserved

Automatic gain control filter

Vertical scale preserved

2nd horizontal derivative (curvature) filter

Arbitrary vertical scale

1st horizontal derivative (gradient) filter

Arbitrary vertical scale

Input

Figure 2.25 Illustration of how data with different characteristics are altered by some of the commonly used filtering operations.

The data contain commonly encountered types of signal and noise. For each filter, the red line is the un ltered input and the blue line is

the filtered output.