Is GPR a safe testing technique?
Many people question whether there is any danger for the person
using GPR equipment, and the answer is no. Although “ground
penetrating radar” may sound like a hazardous technique,
it is extremely safe and emits roughly 1% of the power of a cellular
phone signal.
How does GPR equipment work?
GPR systems work by sending a tiny pulse of energy into a material
via an antenna. An
integrated computer records the strength and time required for the return of
any reflected signals. Subsurface variations will create reflections that
are picked up by the system and stored on digital media. These reflections
are produced by a variety of material such as geological structure differences
and man-made objects like pipes and wire.
Can I see non-metallic subsurface features with GPR?
GPR is extremely accurate when it comes to locating metallic and non-metallic
objects.
GPR systems work by sending a tiny pulse of energy into the ground
from an antenna. An integrated computer records the strength
and time required for the return of reflected signals. Any
subsurface variations, metallic or non-metallic, will cause signals
to bounce back. When this occurs, all detected items are
revealed on the computer screen in real-time as the GPR equipment
moves along. Users can even tell from the signal returned
whether the feature in question is metallic or non-metallic.
How difficult is it to use GPR if I have never used it before?
Our students typically find that GPR is a much easier technology
to learn than they may have believed.
GPR was pioneered by GSSI over 35 years ago, and even though it
began as a tool for scientists, vast improvements over the last
three decades have been made to simplify and perfect this equipment
so anyone in the utility locating, concrete scanning or road inspection
lines of work can use our GPR products with ease.
GSSI provides training with its products and teaches a wide variety
of classes to help the novice and experienced GPR user improve
his or her skills. The classes typically include and introductory
lecture and then lots of hands-on practice with the equipment and
software. This format ensures that each student walks away
with firm knowledge of what GPR is all about and how to use the
equipment in real-life situations.
How much training will I need in order to use GPR?
First time users will need about 2-3 days of training to become
familiar with the equipment and ground penetrating radar theory. Training
is provided free of charge with most GSSI equipment.
How deep can GPR “see” to locate targets?
Depth of GPR penetration depends on the material being surveyed
and also upon the antenna frequency being used. For instance,
GPR will penetrate ice, rock, soil and asphalt differently due
to each material’s unique dielectric properties. Lower
frequency antennas will generally penetrate deeper, but there is
a loss in resolution with the drop in frequency.
Soil conditions can vary tremendously, which in turn affects GPR
penetration. In general, dry sandy soils with little salt
content return excellent survey resolution, but heavy clay-based
soils are difficult to penetrate with GPR. In some situations,
penetration depth may be limited to a few feet or less within clays,
whereas pipes residing in sandy soils could be detected at depths
up to 30 feet.
Your GSSI Application Specialist can help you find the equipment
that is right for your project and profession.
Can GPR be utilized through water?
Yes. GPR can be utilized through fresh water, but it does
not operate where salt water is present.
Can GPR be used through ice?
Yes. GPR works extremely well through ice and snow. They
are some of the most favorable conditions for GPR.
Can GPR be used with GPS?
Yes. GSSI’s systems can integrate with most all GPS
systems. The GPS position data files and GPR scans are automatically
matched within our systems so that the resulting data shows proper
GPS position.
Can GPR be used to find gold?
While GPR is in use with many professional mining companies, the
technology is not well suited to finding coins, gold nuggets or
buried treasure. Metal detectors are more suitable. GSSI
recommends checking with local, state and federal laws before beginning
any treasure-hunting activities.
Can GPR be used to map cemeteries?
Yes. GPR is the best geophysical technique for forensic
victim location and for the mapping of graves in cemeteries. While
we can sometimes image the body directly, GPR responds well to
the disturbances in the soil which are created when a pit is dug
and refilled.
I saw something like this in the movie Jurassic Park and on TV
shows like Crossing Jordan. Can GPR really show the skeleton?
No. That is a Hollywood adaptation of the technique. A
grave will look like a large,
upside-down “U” on the
profile view and a rectangular shape in 3D planview.
Is GSSI equipment FCC certified?
Yes. All GSSI equipment is certified by the United States
Federal Communications Commission (FCC), and GSSI manufactures
the only FCC certified air-launched horn antennas.
Is the equipment big and bulky?
Some of the lower frequency antennas like the 100 MHz can be a
bit large, but in general, GPR equipment is small enough to be
handled by one person. Systems for two common applications,
structural concrete scanning and underground utility locating,
can easily be fit into the trunk of a compact car.
Can I use my cell phone around the equipment?
Since GPR operates by transmitting and receiving electromagnetic
(EM) energy at a particular frequency, cellular phones, two-way
radios and pagers should be turned off as they also transmit EM
energy and will interfere with a survey. If you must have
them on, it is essential to keep these devices at least 25-30 feet
away from the antenna.
What is RADAN and what does it stand for?
RADAN is GSSI’s ground penetrating radar processing software. It
has been developed over the last 20 years to aid in the processing
and interpretation of GPR data. It will run on a regular
laptop or desktop computer and provides the user with many powerful
tools to clean up data and view data in 3D. RADAN is an acronym
that stands for RAdar Data ANalyzer. |
