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|Environmental Technology Listing|
Title of Listing:
|GPR: SIR SYSTEM 2, SIR SYSTEM 10 EM: VEM300 |
| *||Soil, All Listings|
|Soil, Sludge, Solid, Sediment|
|Buried Materials, Soil Types|
The ground penetrating radar (GPR) method measures the travel time of electromagnetic pulses in subsurface materials. An impulse radar system radiates repetitive electromagnetic impulses into the earth. A broad bandwith antenna is usually placed in close proximity and electromagnetically coupled to the ground surface. It is able to detect and measure the depth to reflecting discontinuities in subsurface soils and other earth materials to within a few centimeters depending on the electromagnetic parameters of the earth medium, the depth to and size of the target and the frequency of operation.
As the broad band with antenna is pulled across the ground surface a continuous profile record is generated and displayed as a travel time versus distance plot on a strip chart recorder and/or color monitor for immediate evaluation. Depth calculations can be derived from this data once the signal velocity has been determined. Radar velocities are dependent on the dielectric properties of the media(s) probed.
The electrical conductivity of the materials probed and the frequency of operation determine how deep the radar signals will penetrate through a material. Depths of penetration typically range from 1 to 40 meters. GPR Antenna frequencies range from 16 MHz to 2 GHz for various depth of penetration and resolution requirements. High frequency radar signals have better resolution and less penetration depth than low frequency radar signals. Therefore, low frequency antennas are used for fresh water sub-bottom profiling, mining, geotechnical, geological and hydrogeological studies and higher frequency antennas are used for civil, structural, and mining engineering, archaeological, forensic and environmental studies and the detection of buried objects. Systems are typically deployed as a man portable or vehicle towed system. Modes of operation include continuous reflection profiles, stacked reflection profiles along discrete points of a line and transillumination measurements through materials and between bore
GPR performance is dependent on the electrical properties of the materials probed. There must be a sufficient dielectric contrast between materials to produce a reflection.
Depth of penetration is dependent on the frequency of operation, the electrical conductivity of the materials probed and the amount of subsurface scattering.
GPR has limited penetration in electrically conductive soils such as clay and soils where salt water, brackish water, or contaminants are present.
Scattering of the radar signal may become a dominant form of signal attenuation in soils with a high percentage of rocks and boulders and other erratics if these object's dimensions are approximately 1/2 of the radar signal wavelengths.
Electromagnetic Fields (EMF), Geophysics, Technologies, Characterization
Ground Penetrating Radar, Stratigraphy
|Geophysical Survey Systems, Inc.|
|13 Klein Drive|
PO Box 97
|North Salem |
|Primary ||(603) 893-1109 |
|United States |