Ground penetrating radar (commonly called GPR) is a high resolution electromagnetic technique that is designed primarily to investigate the shallow subsurface of the earth, building materials, and roads and bridges. GPR has been developed over the past thirty years for shallow, high resolution investigations of the subsurface. GPR is a time-dependent geophysical technique that can provide a 3-D pseudo image of the subsurface, including the fourth dimension of color, and can also provide accurate depth estimates for many common subsurface objects. Under favourable conditions, GPR can provide precise information concerning the nature of buried objects. It has also proven to be a tool that can be operated in boreholes to extend the range of investigations away from the boundary of the hole.
Waveform Mode
GPR uses the principle of scattering of electromagnetic waves to locate buried objects. The basic principles and theory of operation for GPR have evolved through the disciplines of electrical engineering and seismic exploration, and practitioners of GPR tend to have backgrounds either in geophysical exploration or electrical engineering. The fundamental principle of operation is the same as that used to detect aircraft overhead, but with GPR that antennas are moved over the surface rather than rotating about a fixed point. This has led to the application of field operational principles that are analogous to the seismic reflection method.
GPR is a method that is commonly used for environmental, engineering, archaeological, and other shallow investigations. The fundamental principles that are described in the following text applies to all of these applications.
Waveform Derivative Mode
AFRASIA uses TERRAVISION-LOZA technology that has a lot of innovations which make it different from its predecessor – ground-penetrating radar. Pulse transmitter power has been increased by a minimum of 100,000 times, and the stroboscopic transformation replaced to direct detection of signal. The antennas used by Terravision-Radar use RC-loaded dipoles. This ensures the exclusion of interference in the received signal that suppresses weak signals, whilst also permitting the reception of strong signals. The transmitter uses a high-pressure hydrogen discharge, and the transmitter operates in stand-alone mode without synchronization. This avoids the requirement for connecting lines which also introduce strong interference from the transmitter.
Binary Mode
The mono-pulse system waveforms create a cross section radar image of the subsurface. As each shot is precisely measured this enables the resulting 3D modeling. The data for processing can be viewed in three typical representations. Colors are for contrast only to delineate structures and common features.
Actual Result of Survey of a Gold-Bearing Body
Copper Mine Case Study
The survey in Chile identified an ore body at depths of 30-70m and a 20m width.
Phase of the signal reflected from the boundaries of the detected object indicates that the rock component of the object has a higher dielectric constant and conductivity. These characteristics show that the detected object can be the ore body containing copper.
