User's Manual

Noggin
G-1
Appendix G GPR Glossaries
G-1 Basic GPR Terms
alpha exponential attenuation coefficient - normal units dB/m (see attenuation)
K relative permittivity or dielectric constant
sigma electrical conductivity - normal units mS/m
v propagation velocity - normal units m/ns
dB/m decibels/metre, common unit for attenuation,
m/ns metre/nanosecond, common unit of GPR velocity, v (see nanosecond)
mS/m milli-Siemens/metre, common unit for conductivity,
ns nanosecond, normal unit of GPR time (see nanosecond)
ps picosecond = 0.001 ns =10
-12
s, occasion unit of GPR time
us microsecond = 1000ns =10
-6
s, occasion unit of GPR time
COR common offset reflection (survey type where a constant antenna separation is main-
tained).
CMP common mid-point (survey type where a transmitter and receiver antenna separation
are changed but the mid point remains constant)
GPR ground penetrating radar
EM electromagnetic (common abbreviation)
antenna Device used to couple electromagnetic energy into the ground. Sometimes called a
transducer.
antenna separation Spacing between transmitting and receiving antennas.
attenuation A reduction in signal amplitude caused by energy dissipation in the transmitting media
(see alpha).
bandwidth The range of frequencies over which a given device transmits or detects signals above
a specified amplitude or power
centre frequency Middle of the frequency band defined by a device's bandwidth
conductivity The ability of a material to conduct electrical current. In isotropic materials the recipro-
cal of resistivity. Sometimes called specific conductance. Units are siemen/m or S/m.
(Or occasionally, mhos/m). For GPR, usually expressed as mS/m. Common symbol
nanosecond 10
-9
s (One Billionth of a second)
radio wave Electromagnetic fields that travel through a material as waves and typically have oscil-
lating frequencies in the 1 GHz to 10 GHz range