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Useful signals
– these are the reflected signals from the real subsurface targets
Most often, these can be single reflections from target horizons and diffracted
waves from target objects.
Not useful signals (interferences)
– these are signals that are not interest from the
task point of view, but are present in the data, forming an interference pattern with
useful signals and making it difficult to truly interpret. These include: hardware
interferences, such as direct wave hiding the useful signals, multiple reflections
from shallow boundaries, many diffracted waves from cracks, boulders, etc.,
reflected and diffracted waves propagating through the air (like wires, power lines,
walls and corners of buildings, objects on the surface of the surface and above it).
Noise
– represents an irregular component of the data, where it is impossible to
distinguish any in-phase axes. The reasons of the noise appearing are irregular
electromagnetic processes in the GPR equipment itself and external
electromagnetic fields of natural and artificial origin (for example, mobile
communication signals). The value of signal-to-noise ratio determines the
processing complexity and the overall efficiency of GPR researches in most cases.
Location marker
– it is a point on the ground, marked by a ground hammered peg,
as well as the peg itself, a punched point or a point marked with permanent paint, a
marker on any structures, a point for marking distances on the ground with a step of
100 m on railway lines or highways.
Mark
– it’s a feature of some profile trace, indicating some uniqueness of this trace
and, consequently, a point of the profiling route. Marks are used to bind the profile
to the terrain. User is able to add marks by pressing the button while passing any
landmarks on the ground or pre-placed pickets. These marks will be displayed
along with the profile, while its output. Marks examples you can see in Fig.4.3.
