1. Ground-Penetrating Radar
Uses pulses of radio waves to image the subsurface (typically MHz)

2. GPR uses Radio Waves to Image the Subsurface
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GPR uses Radio Waves to Image the Subsurface
The Noggin uses advanced impulse radar sensing technology.
Radio waves are generated and detected by the Noggin.
The buried targets are identified by the signals they reflect back to the surface and which are detected by the sensitive Noggin receiver electronics.
All Sensors & Software products are certified to meet regulatory standards around the world. See the FCC label or the CE mark on the labels and serial number plates.
Is the Noggin the universal answer. No! Some soils strongly absord radio signals and exploration depth is limited. Just think about how well you cell phone or car radio work in underground garages or tunnels. Again, don’t get too involved in this discussionb at this point but we need to have the response ready if some one asks. The point we want to get across is that the physics of radio waves limits exploration depth – not the product!. And no one can not increase power indefinitely. First the regulators will catch you out and second the power supply becomes prohibitively large and unwieldy.
This simple animation shows how an “inverted V” (hyperbola in space time) is created when traversing over a pipe.
The apex of V is the point of closest approach to the target. Moving to the top of the inverted V defines the location of the target.
Depth of the target is measured at the top of V. The standard depth calibration gives useful depth estimates. More accurate depths are obtained by using the target fitting feature built into the DVL software right on the unit.
Survey Mode – Reflection Survey
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3. GPR and Seismic Reflection
Displaying GPR data (left) is analogous to a reflection seismic section (right)
Figures 8.13 and 4.48 in Burger, Sheehan, and Jones, 2006

4. EM Wave Properties Characteristics of radar waves
Velocity -- v
Attenuation -- 
Reflection coefficient -- R
Are controlled by the electrical properties of the soil:
Dielectric Permittivity -- K
Conductivity -- 𝞂

5. V = c /(𝝻 K)1/2 ~ c/√K Radar Velocity
In a vacuum: velocity is the speed of light ( c )
In materials:
Relative dielectric permittivity ( K )
Relative magnetic permeability(𝝻)
Normally 1 for geological materials
V = c /(𝝻 K)1/2 ~ c/√K

6. Radar Attenuation 𝜶 = 1.7 x 103 𝞂 / √K
Radar attenuation controls how quickly the radar energy is absorbed by the medium
High attenuation results in poor soil or rock penetration
Attenuation is proportional to conductivity and inversely proportional to dielectric permittivity
at 100 MHz
𝜶 = 1.7 x 103 𝞂 / √K

7. Common Material Electrical Properties @ 100 MHz
Velocity
Conductivity
Attenuation
Material K v 𝞂 a
(m/ns) (mS/m) (dB/m)
Air
Distilled Water x10-3
Fresh Water
Sea Water x
Dry Sand
Saturated Sand
Limestone
Shales
Silts
Clays
Granite
Dry Salt
Ice
Metal ~0 ∞ ∞

8. GPR Limitations
Does not work well in presence of high surface conductivity (e.g. wet clays or conductive fluids) but it does work well in regions of ice, snow, dry sandy soil, or over concrete.

9. Reflections are caused by Contrasts in Dielectric Permittivity
Incident
Reflected K1 K2
Transmitted
K1- K2
R =
K1+ K2

10. Reflection Strength depends on the Contrast of Materials
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Reflection Strength depends on the Contrast of Materials
Material 1 K1
Material 2 K2
Reflectivity
Air 1
Dry Soil 5
-38%
Wet Soil 25
Rock 6
-5%
34%
Water 80
57%
Ice 3
-67%
Permafrost
-34%
Soil 12
Metal
-99%
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11. Resolution and Depth
Smallest resolvable layer is assumed to be of thickness ( λ/4 ) where ( V = f λ )
higher frequencies have higher resolution; however, they have small penetration depths
lower frequencies have lower resolution; however, they have large penetration depths

12. GPR for Subsurface Imaging
Antenna Center Frequency
500 MHz
1000 MHz
Freq.
(MHz)
Wave
length (m)
12.5 12 25 6 50 3
100
1.5
250
0.6
500
0.3
1000
0.15
Typical Application
Glaciology
Geology
Utility Locating
250 MHz
Archaeology
Forensics
Roads
Concrete
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13. GPR for Subsurface Imaging
Frequency
12.5 25 50
100
200
Lower Frequency = longer wavelength = deeper penetration = less resolution
Higher Frequency = shorter wavelength = less penetration = more resolution
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14. GPR for Subsurface Imaging
Frequency vs. Depth
Frequency (MHz)
Depth (m)
Depth (ft)
12.5
50+
165+ 25 30
100 50 10 33 5 16
200 2 6
500 1 3
1000
0.5
1.5
Values are based on practical experience.
Should only be used as a quick guide.
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15. Data Acquisition
Data is collected by moving a transmitter and a receiver antenna over the area continuously broadcasting and receiving radar waves. The antenna are usually separated by a fixed distance and moved together.
Figure 8.15 in Burger, Sheehan, and Jones, 2006

16. GPR for Subsurface Imaging
Antenna Center Frequency
500 MHz
1000 MHz
Freq.
(MHz)
Wave
length (m)
12.5 12 25 6 50 3
100
1.5
250
0.6
500
0.3
1000
0.15
Typical Application
Glaciology
Geology
Utility Locating
250 MHz
Archaeology
Forensics
Roads
Concrete
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17. pulseEKKO PRO SmartCart with Antennas
GPR for Subsurface Imaging
pulseEKKO PRO SmartCart with Antennas
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18. GPR for Subsurface Imaging
SmartChariot
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19. Applications
Historic cemetery in Alabama (yellow arrows are strong reflectors, red arrows are weak reflectors, and blue lines are bedrock interfaces

20. Diffraction Hyperbola
Radar waves go out in all directions so the strongest reflections may not be directly below the radar antennas
Figures 8.21 and 8.19 in Burger, Sheehan, and Jones, 2006

21. Utility SmartCart Training
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22. Utility SmartCart Training
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23. Utility SmartCart Training
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24. Utility SmartCart Training
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25. Utility SmartCart Training
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26. Utility SmartCart Training
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27. Utility SmartCart Training
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28. Velocity Calibration Method: Hyperbola Matching
GPR for Subsurface Imaging
Velocity Calibration Method: Hyperbola Matching
Velocity and depth can be extracted by matching the shape of a hyperbola in the data with an adjustable on-screen overlay of a hyperbola
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29. Water Table Reflection

30. Water Table One of the strongest reflecting horizons – large dielectric permittivity contrast K= 5 to K = 25

31. Applications
SHARAD (SHAllow RADar) aboard the Mars Reconnaissance Orbiter Spacecraft
15 – 25 MHz
Hres = km
Vres = m