introduction to ground penetrating radar
TRANSCRIPT
![Page 1: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/1.jpg)
Introduction to Ground Penetrating Radar
Bryan S. Haley
![Page 2: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/2.jpg)
Introduction
![Page 3: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/3.jpg)
History• 1920s: rudimentary GPR, applications such as
ice thickness• Air radar used in WWII for aircraft, Radio
Detection and Ranging (RADAR) acronym• 1950s,60s: ice thickness, geological applications• 1972: NASA Apollo 17 on moon, carrying GPR • 1980s: engineering applications, concrete
assessment, void detection, land mine detection
![Page 4: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/4.jpg)
History of GPR in Archaeology
1970s and 1980s• Chaco Canyon,
Cyprus, Ceren, Japan• Analysis of raw profile
data from plotters
![Page 5: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/5.jpg)
History of GPR in Archaeology1990s and 2000s
• Computers more powerful and affordable
• Onboard storage• Time slice maps, 3D
modeling, rendering, etc.
![Page 6: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/6.jpg)
How Does It Work?
![Page 7: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/7.jpg)
How Does It Work?
Trace Profile
![Page 8: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/8.jpg)
Relative Dielectric Permittivity (RDP)RDP( ) = (c / V)2
• Ranges from 1 (air) to 81 (water).
• Related primarily to water content of materials.
• Higher ε values mean less radar penetration (more attenuation).
• Strength of reflection is controlled by RDP contrast between the two materials.
• A reflection can occur in dielectric contrasts as small as 1.
ε
c: speed of light in a vacuum (3 X 108 m/s)
V: velocity of radar wave through the material
![Page 9: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/9.jpg)
Conductivity (σ)• High σ inhibits radar penetration (more attenuation).• Increases with moisture content, and salinity.• So highly conductive soils (ie. clays) are not as ideal for
GPR investigation as soils with low σ (such as dry sand).
Magnetic Permeability (μ)• High μ inhibits radar penetration (more attenuation).
• Most soils have relatively low μ.
Other Properties
![Page 10: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/10.jpg)
Conductivity and RDP for Common Materials
![Page 11: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/11.jpg)
Strength of ReflectionReflection Strength = √ε2 - √ε1 / √ε2 + √ε1
ε1: RDP of first material
ε1: RDP of second material
![Page 12: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/12.jpg)
Strength of Reflection
Reflection coefficient for 2 layer case. From GSSI SIR System-2000 Training Notes 1999.
![Page 13: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/13.jpg)
Anomaly Shape
Simulations From GPRSIM 2D Forward Modeling Software
![Page 14: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/14.jpg)
Antennas
• Identified by center frequency in MHz
• Higher frequency = greater vertical resolution
• Lower frequency = greater penetration depth
• Typical penetration depths
100Mhz 4-25m
300Mhz 1-10m
400Mhz .5-4m
500Mhz .5-3.5m
900Mhz 0-1m
![Page 15: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/15.jpg)
Vertical Resolution
Tm = c / (4f √ε)
Tm: minimum thickness resolved.
c: speed of light in a vacuum (3 X 108 m/s).
f: center frequency of antenna.
ε: RDP.
Example: For 400 Mhz antenna and RDP of 10, the minimum thickness is about 6 cm.
Antennas
![Page 16: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/16.jpg)
AntennasHorizontal Resolution
A = λ / 4 + D / √ (ε + 1)
• A = long dimension radius of footprint.• λ = center frequency wavelength of antenna.• D = depth.
• ε = RDP.
Example: For 400 Mhz antenna, a depth of 50 cm, and a RDP of 10, A is about 21 cm. Therefore the footprint is approximately 42 cm on the front to back axis and 28 cm on the side to side axis.
![Page 17: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/17.jpg)
Antennas
Simplified antenna patterns.
![Page 18: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/18.jpg)
Setup: Gaining
No Gain 5 Gain Points
![Page 19: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/19.jpg)
Other Setup Parameters• Samples per scan (512)• Scans per time (16 to 64 / sec)• Bit depth of data (8 bit or 16 bit)
![Page 20: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/20.jpg)
Determining Position
User Marks• Marks inserted manually
with trigger at fixed interval.Survey wheel
• Calibrated so that distance is determine based on number of revolutions.
GPS• Location determined by
GPS and synched with GPR based on time.
![Page 21: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/21.jpg)
• Must record file name, X value, and Y start and finish
• Very important for GPR since software is flexible
• Basic instrument settings
Field Notes
![Page 22: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/22.jpg)
Depth (Velocity) Estimation• Estimate from RDP.• Shoot to target of known depth.• Hyperbola fitting (geometric scaling).• Common Mid Point (CMP) testing.
![Page 23: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/23.jpg)
Hardware
• GSSI– SIR 2000– SIR 3000
• Sensors and Software– Noggin
• Mala
• Others
![Page 24: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/24.jpg)
Processing Steps Radargram Processing
• Background removal• Box car filter• Band pass filter• Migration• Hilbert Transform• Topographic Correction• Antenna tilt correction
![Page 25: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/25.jpg)
Processing Steps Create Info File
• Contains file name, X value, and Y start and finish.
Reverse Files• Align zig-zagged lines.
Set Navigation• Specify survey wheel,
user marks, GPS.• Fix marks if there are
errors.
![Page 26: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/26.jpg)
Processing StepsSlice / Resample
• Set # of slices, thickness.• Radargrams resampled to
constant number per distance unit.
• Data collected from each radargram.
• Time slice values computed for each radargram are merged with the navigation.
• XYZ file created for each slice.
0.25 0.0625 12720.25 0.3125 15410.25 0.5625 12820.25 0.8125 17720.25 1.0625 16150.25 1.3125 13870.25 1.5625 1680
![Page 27: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/27.jpg)
Processing StepsGridding
• Specify cell size, search radius.• Interpolate the XYZ files already created.
0.25 0.0625 12720.25 0.3125 15410.25 0.5625 12820.25 0.8125 17720.25 1.0625 16150.25 1.3125 13870.25 1.5625 1680
![Page 28: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/28.jpg)
Time Slices• Processing: low pass, high pass, etc.• Set color scheme• Set data range• Set transforms
![Page 29: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/29.jpg)
3D Data Cubes
![Page 30: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/30.jpg)
Isosurface Rendering
![Page 31: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/31.jpg)
Animations
![Page 32: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/32.jpg)
Support Software
• Surfer
• ArcView / ArcGIS
![Page 33: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/33.jpg)
Interpretation•Anomaly Shape / Size / Orientation
•Strength / Amplitude
•Context
•Multiple Instrument Response
•Data from other projects•Historic Documents•Aerial Photos•Lore•Etc.•Ground Truthing
![Page 34: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/34.jpg)
Results
![Page 35: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/35.jpg)
For More Reading…
• Conyers and Goodman 1997
• Conyers 2004
• Heimmer and Devore 1995
• Bevan 1998
• Clark 1995
• Gaffney and Gater 2003
• Johnson 2006
![Page 36: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/36.jpg)
Part II: Case Studies
Bryan S. Haley
![Page 37: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/37.jpg)
Sapelo Island Shell Rings (Georgia)
![Page 38: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/38.jpg)
Sapelo Island
Reconstruction
![Page 39: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/39.jpg)
Sapelo Island
Early sketch map. Modern topo map.
![Page 40: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/40.jpg)
Sapelo Island
![Page 41: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/41.jpg)
Sapelo Island
![Page 42: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/42.jpg)
St. Michael’s Cemetery (Pensacola FL)
![Page 43: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/43.jpg)
St. Michael’s Cemetery
![Page 44: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/44.jpg)
St. Michael’s Cemetery
![Page 45: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/45.jpg)
St. Michael’s Cemetery
![Page 46: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/46.jpg)
St. Michael’s Cemetery
![Page 47: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/47.jpg)
Memorial Cemetery (St. Genevieve Missouri)
![Page 48: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/48.jpg)
Memorial Cemetery
![Page 49: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/49.jpg)
Memorial Cemetery
![Page 50: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/50.jpg)
Memorial Cemetery
![Page 51: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/51.jpg)
Belle Alliance (Louisiana)
![Page 52: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/52.jpg)
Belle Alliance
![Page 53: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/53.jpg)
Belle Alliance
![Page 54: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/54.jpg)
Belle Alliance
![Page 55: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/55.jpg)
Jackson Barracks (New Orleans)
![Page 56: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/56.jpg)
Jackson Barracks
Possible Burial
![Page 57: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/57.jpg)
Jackson Barracks
Possible Burials
![Page 58: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/58.jpg)
Jackson Barracks
Interpretation
![Page 59: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/59.jpg)
Hollywood (NW Mississippi)
1923 Sketch Map of Mounds
![Page 60: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/60.jpg)
Hollywood
![Page 61: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/61.jpg)
Hollywood
Excavated Structures
![Page 62: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/62.jpg)
Hollywood
![Page 63: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/63.jpg)
Cahal Pech (Belize)
![Page 64: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/64.jpg)
Cahal Pech
![Page 65: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/65.jpg)
Cahal Pech
![Page 66: Introduction to Ground Penetrating Radar](https://reader034.vdocuments.mx/reader034/viewer/2022042501/546a6371b4af9fb64e8b45dc/html5/thumbnails/66.jpg)
Cahal Pech
Excavated Structure