Ground Penetrating Radar (GPR) also called georadar, is an electronic equipment for testing geophysical properties of the soil and rocks. This device works on the principle of counting delays electromagnetic (EM) pulses of high frequency (10 - 1000 MHz) transmitted by the transmitting antenna, which is reflected from the various centers of the layers (lithological boundaries) are received by the receiving antenna and transmitted to a central processing unit for counting the time delays return wave. Across borders reflecting the radar signal must be understood boundaries between the centers of differing value of the dielectric constant (E). Various rocks and materials are characterized by different values of the dielectric constant.
The GPR research results are echogram, which can be compared with standard images of various objects hidden in the ground or with standard images of geological structures, documentation mapping of outcrops, as well as the data obtained from the drilling (geological, geotechnical , etc.).
GPR (eg RAMAC/GPR), a battery-powered portable equipment 12V is applied to the field of research from the surface. The GPR Method allows to linear radar tracking of the geological structure in the area. The use of interchangeable power antennas such as 10 MHz, 25 MHz, 50 MHz, 100 MHz, 200 MHz, 400 MHz, 500 MHz, 800 MHz, 1 GHz, etc. dependent on the task and monitoring of the assumed depth of soil (rock).
The low frequency antennas have the greater range of depth profiling, and lower accuracy of the shallower layers. In studies of shallow geological structures (and shallow soil layers) are used high frequency antennas.
GPR Studies are conducted in two stages:
Prior to GPR testing should be clearly stated aim and scope of the research:
While research is necessary to have accurate situational plans or topographic maps of the study area (elevation ordinates of points repaired), to determine the course of the profiling (ie, onset, course and end of the profile). Also necessary are recent photographs of land cover.
During the GPR study it is necessary to have lithological data from standard drilling (or information from outcrops) to determine the point of "0" and to determine the depth (eg meter) ceilings of the individual layers of rock.
GPR Research should overtake drilling projects or GPR survey should cooperate with the drilling rig to limit the amount of drilling. GPR Research should overtake the archaeological work to limit the area to reduce the cost of excavation and earthwork excavation.
In the design of the research is necessary to determine what the conditions of administration are: whether the area is equal to or dug up (or is moguls, piles of debris, etc.). In the case of equal area can be used shielded antenna, but in the case of work on uneven ground more useful antennas are unshielded. The study in boreholes or manhole can be used Borehole Radar.
Very effective are multi-channel GPR systems with 3D software. GPR equipments placed in a mobile robots are useful in the military (e.g., personal and tank min exploration), and are also used in space (MARS PROJECT). Great idea GPR structures are used for observing the movement of rock masses (eg, landslides, glaciers) with computer programs 4D.