GPR Ground Penetrating Radar Ground Penetrating Radar GPR
- Slides: 23
GPR Ground Penetrating Radar
• Ground Penetrating Radar (GPR) is a tool archaeologists will use more and more for excavations in the 21 st century. GPR allows archaeologists to survey archaeological sites in a short amount of time with precision and without digging.
Basic Principles • Uses radio waves to create picture of underground before excavation • Picture is used to locate any variations in the sub-surfaces
Basic Mechanism • Electrode magnetic waves emitted into the ground and time measured for wave to be reflected and received • When wave hits areas of change in soil, it is hit back to receiver antenna • Changes in soil can include objects buried underneath the surface
• Greater surface difference = Stronger signal • Strong signal has large amplitude • Weak signal has small amplitude • Amplitude wavelength and time are used to create image of what is underground
RDP Relative Dielectric Permitivity • “RDP is ability of a material to store and allow passage of electromagnetic energy when a field is imposed upon it. ” • RDP of a substance = electrical permitivity / vacuum
K = RDP C = Speed of light V = Velocity of radar energy
GPR Depth Determination D = (5. 9 t)/sqrt of (Er) D = depth of target (in) t = wave travel time (nanosec) 5. 9 = a constant incorporating speed of light and unit conversions Er = dielectric constant of subsurface material Dielectric constants for common materials Air 1 Pure water 81 Fresh water (ice) 4 Granite (dry) 5 Clay (saturated) 8 -12 Sand (dry) 4 -6 Sand (saturated) 30
Example How deep below the surface is an object that is detected at 46 ns in dry sand (Er = 4)? Answer: D = (5. 9 x 46) / sqrt (4) D = 135. 7 in Therefore the object is about 11 ft underground
Equipment • Consists of: 1. control unit 2. display unit 3. transmitting and receiving unit
Case Studies • Cave of Letters • Bethesaida, Israel • Forum Novum
Cave of Letters • Site located in Nahal, Hever (a canyon by the Dead Sea) • GPR was used to map possible excavation sites in the Cave of Letters
Artifacts Found • Coins • Clothes • Letters mentioning Jewish leader Bar. Kokhba who had fought against the Romans around the middle first century
Bethesaida, Israel • Located in Northern Israel near the sea of Galilee • Was an active fishing community 2000 years ago • Site where Jesus healed a blind man and walked on water
Overview Movie • http: //www. joeinfo. com/gpr/overview. MOV
Bethsaida Excavation • GPR has tested land for cave locations • Artifacts found: 1. coins (dated as far back as 1 st and 2 nd Century) 2. child’s sandal 3. fabric 4. pottery 5. human bones and remains
Antenna Movie • http: //www. joeinfo. com/gpr/antenna. MOV
• Recently, Dr. Harry Jol, professor of geography at the University of Wisconsin - Eau Claire, used GPR to map an area by the city gates of Bethsaida
Vescovio, Italy • Romaneque church of Santa Maria • Remains of marketplace, living quarters, storage areas, hallways and door entrances reconstructed visually
Forum Novum • Remains of marketplace, living quarters, storage areas, hallways and door entrances reconstructed visually • Believed to be Roman marketplace which initially began construction in the 1 st century BC and flourished through the 4 th century AD as the Roman town of the Forum Novum
Excavation • British School of Archaeology in Rome have conducted excavation sites • Sites include: 1. an amphitheatre 2. a bath complex 3. the villa 4. a tomb complex 5. crypts from the 8 th to 9 th centuries located behind the church
GPR reading from Forum Novum
Wrap up… • GPR usage has become more wide-spread • Now used in construction • Average person can now purchase GPR equipment
- Civil engineering applications of ground penetrating radar
- Ground penetrating radar
- Gpr survey
- Gpr rectapur grade definition
- General purpose reloadable
- Non penetrating glaucoma surgery
- Ppgbqa
- Pulse frequency
- Mti versus pulse doppler radar
- Magellan radar
- Stalker speed trailer
- Radar systems engineering course
- Cotrec
- Tipi di radar
- Matthew shupe
- Agility health radar
- Nrot radar
- Blacksburg doppler radar
- Tmd weather chart
- Pulsed coherent radar
- Cinematica radar
- Primary vs secondary surveillance radar
- Shmu radar maly javornik
- Software encompasses