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4. DATA REDUCTION
4.1 Deformation Calculation
The basic unit utilized by Geokon for measurement and reduction of data from Vibrating Wire
Displacement Transducers is "digits". Calculation of digits is based on the following equation:
Digits =
�
1
Period
�
2
x 10
-3
or Digits
=
Hz
2
1000
Equation 1 - Digits Calculation
To convert digits to deformation use Equation 2.
Duncorrected = (R
1
- R
0
)
×
G
×
F
Equation 2 - Displacement Calculation
Where;
R
1
is the current reading.
R
0
is the initial reading, usually obtained during installation (see Section 2.2).
G is the calibration factor, usually millimeters or inches per digit.
F is an optional engineering units conversion factor, see Table 2.
From
→
To
↓
Inches
Feet
Millimeters
Centimeters
Meters
Inches
1
12
0.03937
0.3937
39.37
Feet
0.0833 1
0.003281
0.03281
3.281
Millimeters
25.4
304.8
1
10
1000
Centimeters
2.54
30.48
0.10
1
100
Meters
0.0254 0.3048 0.001
0.01
1
Table 2 - Engineering Units Conversion Multipliers
For example, if the initial reading (R
0
) is 6783 digits, the current reading (R
1
) is 7228, and the
calibration factor (G) is 0.011906 mm/digit, then the deformation change is calculated as
follows:
D = (7228
−
6783)
×
0.011906 = +5.3 mm
(Note that increasing readings [digits] indicate increasing extension.)
