3 ms·

Ground-Penetrating Radar

peter_d_sherman 6y ago
>"Archaeology Ground penetrating radar survey is one method used in archaeological geophysics. GPR can be used to detect and map subsurface archaeological artifacts, features, and patterning.[7] GPR depth slices showing a crypt in a historic cemetery. These planview maps show subsurface structures at different depths. Sixty lines of data – individually representing vertical profiles – were collected and assembled as a 3-dimensional data array that can be horizontally "sliced" at different depths.) GPR depth section (profile) showing a single line of data from the survey of the historic crypt shown above. The domed roof of the crypt can be seen between 1 and 2.5 meters below surface. The concept of radar is familiar to most people. With ground penetrating radar, the radar signal – an electromagnetic pulse – is directed into the ground (it is important to not get GPR surveys confused with electromagnetic surveys, a recent survey of an Iron Age hillfort in Hampshire recently revealed the discrepancies between Magnetometry, EM and GPR surveys over the same area). Subsurface objects and stratigraphy (layering) will cause reflections that are picked up by a receiver. The travel time of the reflected signal indicates the depth. Data may be plotted as profiles, as planview maps isolating specific depths, or as three-dimensional models. GPR can be a powerful tool in favorable conditions (uniform sandy soils are ideal). Like other geophysical methods used in archaeology (and unlike excavation) it can locate artifacts and map features without any risk of damaging them. Among methods used in archaeological geophysics, it is unique both in its ability to detect some small objects at relatively great depths, and in its ability to distinguish the depth of anomaly sources. The principal disadvantage of GPR is that it is severely limited by less-than-ideal environmental conditions. Fine-grained sediments (clays and silts) are often problematic because their high electrical conductivity causes loss of signal strength; rocky or heterogeneous sediments scatter the GPR signal, weakening the useful signal while increasing extraneous noise." PDS: Also, Ground-Penetrating Radar (GPR) -- is Star Trek's planetary scanners -- just version 0.0000001... <g>

>"Archaeology Ground penetrating radar survey is one method used in archaeological geophysics. GPR can be used to detect and map subsurface archaeological artifacts, features, and patterning.[7] GPR depth slices showing a crypt in a historic cemetery. These planview maps show subsurface structures at different depths. Sixty lines of data – individually representing vertical profiles – were collected and assembled as a 3-dimensional data array that can be horizontally "sliced" at different depths.) GPR depth section (profile) showing a single line of data from the survey of the historic crypt shown above. The domed roof of the crypt can be seen between 1 and 2.5 meters below surface. The concept of radar is familiar to most people. With ground penetrating radar, the radar signal – an electromagnetic pulse – is directed into the ground (it is important to not get GPR surveys confused with electromagnetic surveys, a recent survey of an Iron Age hillfort in Hampshire recently revealed the discrepancies between Magnetometry, EM and GPR surveys over the same area). Subsurface objects and stratigraphy (layering) will cause reflections that are picked up by a receiver. The travel time of the reflected signal indicates the depth. Data may be plotted as profiles, as planview maps isolating specific depths, or as three-dimensional models. GPR can be a powerful tool in favorable conditions (uniform sandy soils are ideal). Like other geophysical methods used in archaeology (and unlike excavation) it can locate artifacts and map features without any risk of damaging them. Among methods used in archaeological geophysics, it is unique both in its ability to detect some small objects at relatively great depths, and in its ability to distinguish the depth of anomaly sources. The principal disadvantage of GPR is that it is severely limited by less-than-ideal environmental conditions. Fine-grained sediments (clays and silts) are often problematic because their high electrical conductivity causes loss of signal strength; rocky or heterogeneous sediments scatter the GPR signal, weakening the useful signal while increasing extraneous noise." PDS: Also, Ground-Penetrating Radar (GPR) -- is Star Trek's planetary scanners -- just version 0.0000001... <g>