ABEM Terrameter SAS 1000 / SAS 4000
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It is possible to select pre-defined electrode
geometries from a protocol file that has been
uploaded using the “Transfer/Install XYZ
file” option in the Utility software (see
Section 8.1.6 Format of VES Protocol Files
,
page 63). Press
to select the desired
measurement protocol.
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When you are finished, move to the
measuring menu by pressing the
knob.
By pressing
the electrode separations
meny
is
reached.
If
a
pre-defined
measurement protocol was selected, the
<AB+> and <MN+> commands can be used
to increase electrode separations, and <AB->
and <MN-> to reduce them. Otherwise the
electrodes separations can be adjusted
manually by pressing
and using
/ and
to step up or down the values.
Perform a measurement by pressing
. The
result is presented in this window.
Ch P1 P2 Resistance S.Dev% Stacks
1:
2: ___
3: ___
4: ___
C: I=Auto
N=0 R00004.S4K Free=100%
Press (+/-) for more...
Ch P1 P2 Resistance S.Dev% Stacks
1:
2: ___
3: ___
4: ___
C: I=Auto
N=0 R00002.S4K Free=100%
Next: AB/2=0.56 Ch1MN/2=0.10 Press +/-
3.4
MEASURING MODES OF THE SAS 1000 / 4000
The Terrameter SAS 1000 / 4000 can operate in different modes, Resistivity, Self Potential
and Induced Polarization. In all modes the SAS 4000 is capable of measuring simultaneously
in four channels. This makes it suitable for all sorts of resistivity surveys.
3.4.1
Statistical description - mean or median
The Terrameter SAS 1000 / 4000 can use either of two different metrics for describing the
statistical characteristics in the data: mean or median. The mean value is simply the sum of
the individual stacked values, divided by the number of stackings. The median is the value in
the "middle" of the ensemble of stacked values. As an example, consider the following four
readings: 12, 31, 13, 12
The mean value is 17 and the median is 12.5. It is obvious that the median is more stable
against blunders. As default, the SAS 1000 / 4000 uses the median when presenting the result.
For both metrics, the standard deviation is calculated and displayed (and saved on the file
together with the measured value).