Specifications

University of Pretoria etd – Combrinck, M (2006)
(c)
-0.05
0
0.05
0.1
0.15
0.2
0.25
0 200 400 600 800
Depth [m]
Imaged Conductivity [S/m]
(d)
-0.05
0
0.05
0.1
0.15
0.2
0.25
0 200 400 600 800
Depth [m]
Imaged Conductivity [S/m]
(a)
-0.05
0
0.05
0.1
0.15
0.2
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0 200 400 600 800
Depth [m]
Imaged Conductivity [S/m]
Lagrange Three-Point
Cubic Spline
Inverse o f Integr ati on
(b)
-0.05
0
0.05
0.1
0.15
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0.25
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Depth [m]
Imaged Conductivity [S/m]
Figure 4-9: Comparison of S-layer differential transform results for the three numerical
differentiation methods applied on (a) unequally spaced data points without smoothing of data,
(b) unequally spaced data points with smoothing of data, (c) equally spaced data without
smoothing and (d) equally spaced data with smoothing.
1.4.4 Comparison of differentiation methods on field data
Four soundings are chosen from a field data set to represent both clean and noisy data
(Figure 4-10) and all twelve processing combinations are applied to these soundings. The
data were acquired with a Geonics Protem system in the central loop sounding
configuration utilising a 100mX100m transmitter loop, 15A current, 25Hz base frequency
and effective receiver area of 100m
2
. Figures 4-11 to 4-16 summarise the results with (a)
unequally spaced data points without smoothing of data, (b) unequally spaced data points
with smoothing of data, (c) equally spaced data points without smoothing of data and (d)
equally spaced data points with smoothing every time.
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