Geophysical Survey Systems, Inc.
SIR® 4000
Manual
MN72-433 Rev F
154
Appendix G: Glossary of Terms and
Suggestions for Further Reading
Antenna:
a paired transmitter and receiver that sends electromagnetic energy into a material and receives
any reflections of that energy from materials in the ground. Also called a transducer. Antennae are
commonly referred to by their center frequency value (i.e. 400 MHz, 1.5 GHz). This frequency
determines the depth of penetration and the size of the objects or layers visible.
Attenuation:
the weakening of a radar pulse as it travels through different materials.
Center Frequency:
the median transmit frequency of an antenna. The antenna will also transmit energy
at a frequency range of 0.5-2 times its center value. For example, a 400 MHz antenna may actually
transmit at a range from 200-800 MHz.
Clipping:
occurs when the amplitude of a reflection is greater than the maximum recordable value. The
system disregards the true value of the reflection and writes in the maximum allowable value. Clipping
appears in the O-Scope as signal that “goes off the scale” at the sides of the window.
Dielectric permittivity:
the capacity of a material to hold and pass an electromagnetic charge. Varies
with a material’s composition, moisture, physical properties, porosity, and temperature. Used to calculate
depth in GPR work.
EM:
Acronym for electro-magnetic.
FCC:
Acronym for Federal Communications Commission. The United States governmental body that
oversees the UWB industry of which GPR is a part.
Gain:
amplifying the signal to certain section of a radar pulse in order to counteract the effects of
attenuation and make features more visible.
GHz:
Acronym for Gigahertz. A measurement of frequency equal to one billion cycles per second.
GPR:
Acronym for Ground Penetrating Radar.
Ground-coupling:
the initial entry of a radar pulse into the ground.
Hyperbola:
an inverted “U.” The image produced in a vertical linescan profile as the antenna is moved
over a discrete target. The top of the target is at the peak of the first positive (white in a grayscale color
table) wavelet.
Interface:
the surface separating materials with differing dielectric constants or conductivity values.
KHz:
Acronym for Kilohertz. A measurement of frequency equal to one thousand cycles per second.
Linescan:
commonly used method of depicting a radar profile. Linescans are produced by placing
adjacent scans next to each other and assigning a color scheme to their amplitude values.
Macro:
a preset list of processing options that may be applied to perform repetitive functions on an entire
dataset. Macros may be created and edited to include different functions (see RADAN manual for
addition information).
Mark:
point inserted along a survey line manually by the operator or at preset intervals.
MHz:
Acronym for Megahertz. A measurement of frequency equal to one million cycles per second.
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