Sensors & Software Inc. NG250 ユーザーズマニュアル

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