Information Technology Reference
In-Depth Information
Fig. 11.23
Apparent-
resistivity curves filtered by
the rectangular window
x
i
−
x
j
⎨
⎩
⎬
⎭
q
14 s)
j
e
−
j
=
1
Z
xy
(
T
n
τ
=
Z
flt
14 s)
i
=
x
i
−
x
j
xy
(
T
=
,
(11
.
12)
⎧
⎨
⎩
⎬
⎭
q
j
=
1
e
−
n
τ
where
τ
and
q
are the filter half-width and steepness. The low-frequency filtration of
Z
xy
(
T
14 s)
with
1 results in
Z
flt
14 s)
. Now we can
=
τ
=
7.5 km and
q
=
xy
(
T
=
calculate correction factors
Z
flt
14s)
i
xy
(
T
=
Z
xy
(
T
14s)
i
K
i
=
=
and obtain smoothed values
Z
flt
xy
(
T
)
i
K
i
Z
xy
(
T
)
i
for all
T
>
14 s
.
In this way
=
we construct graphs of
Z
flt
xy
. The apparent-resistivity curves of
Z
flt
xy
2
flt
xy
=
/
0
are shown in Fig. 11.25.
11.1.4 Fitting Apparent Resistivities to Reference Level
It is simply evident that averaging and filtering of the apparent-resistivity curves
entail the information losses. In order to avoid these losses, we can use techniques
based on fitting the shifted apparent-resistivity curves to some reference level.
