The ground penetrating radar (GPR) uses one high frequency
electromagnetic pulse emitted vertically into the ground. The transmitter provides the high-frequency
(25 MHz to 1,500 MHz) electromagnetic signals that penetrate the ground
and are reflected from objects and boundaries that have a different
dielectric constant from their host material. The reflected waves are
detected by the receiver and stored in memory.
ADVANTAGES
Non-destructive, environmental friendly method
Data can be recorded quickly
High resolution
Continuous data
GPR data can be recorded quickly and the data is presented on a
screen during the survey allowing its quality to be evaluated. If the
resolution or penetration depth are not appropriate then the antenna
frequency can be changed.
DATA STRUCTURE
Data are recorded in digital form in one PC. Parallel profiles are
often used in order to cover large areas. Each profile consists of one
set of reflection "seismograms" or better: "radagrams" on witch all subsurface
features are presented clearly.
In this picture on the right, a road scan is presented. Data are raw,
unfiltered.
In this picture, the above raw data are filtered with one strong
background noise removal filter. The sub-base deterioration of this
pavement is now obvious between the offset of 120 to 128 m.
