Sensors & Software LMX200 Series, User Manual

Page: 51 / 133

GPR Concepts
51
Material Soil Cal
Air 300
Ice 160
Dry Soil 140
Dry Rock 120
Soil 100
Wet Rock 100
Concrete 100
Pavement 100
Wet Soil 65
Water 33
5.5 Air Waves
Some hyperbolas are caused by air wave reflections from objects above ground, such as posts,
fences, overhead wires, and trees.
The following image displays how air wave reflections affect data:
An important part of understanding the data image is learning to recognize these unwanted "air"
targets and distinguish them from the targets in the ground. Good field notes are indispensable
for helping identify unwanted events on the data.
The best way to identify air reflections is the target hyperbola method. Hyperbolas from above
ground objects are wider than objects in the ground and will have a Soil Cal at, or close to, 300.
To learn more, see Soil Cal ( Section 6.7.6).