1,721,047 research outputs found
Positioning System for data acquisition
No full textThe positioning system called PSG (Pad System for Georadar) was developed for “true” 3D acquisitions over small areas. The system allows the easy and fast acquisition of a geo-referred, regular and dense matrix of GPR traces that satisfies the Nyquist theory for both in-line and cross-line directions. The GPR antenna passes over a soft pad (size varies) which can be rolled up for transport purposes, and which is adaptable to the different distances used in surveys. The pad has parallel grooved tracks incorporated in its surface, and there is a matching grooved pad on the bottom of the antenna. The survey is done by dragging the GPR antenna along the grooved tracks of the pad, allowing the rapid acquisition of parallel and regularly spaced profiles. The material of the PSG pad is soft enough to adapt to the irregularity of the soil surface, so the antenna slides smoothly across the pad, while the friction between the bottom of the pad and the soil surface prevents any movement of the PSG device. The PSG can simultaneously ensure position accuracy, constant antenna orientation, and full coverage of a regular point-measurement grid without the same point being investigated twice
Utilizzo della tecnica georadar per la ricerca delle strutture in legno negli edifici storici
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2D and 3D experiments to explore the potential benefit of GPR investigations in planning the mining activity of a limestone quarry
No full textGPR investigations to reconstruct the geometry of the wooden structures in historical buildings
No full textRecenti progressi nella tecnologia GPR e loro impatto sulle applicazioni per la diagnostica
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Combining orthogonal polarization for elongated target detection with GPR
Full text linkFor an accurate imaging of ground penetrating radar data the polarization characteristics of
the propagating electromagnetic (EM) wavefield and wave amplitude variations with antenna
pattern orientation must be taken into account. For objects that show some directionality
feature and cylindrical shape any misalignment between transmitter and target can strongly
modify the polarization state of the backscattered wavefield, thus conditioning the detection
capability of the system. Hints on the depolarization can be used to design the optimal GPR
antenna survey to avoid omissions and pitfalls during data processing.
This research addresses the issue of elongated target detection through a multi azimuth
(or multi polarization) approach based on the combination of mutually orthogonal GPR data.
Results from the analysis of the formal scattering problem demonstrate how this strategy can
reach a scalar formulation of the scattering matrix and achieve a rotational invariant quantity.
The effectiveness of the algorithm is then evaluated with a detailed field example showing
results closely proximal to those obtained under the optimal alignment condition: detection is
significantly improved and the risk of target missing is reduce
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