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6
4. DATA REDUCTION
4.1. Displacement Calculation
The basic units utilized by Geokon for measurement and reduction of data from Vibrating
Wire Displacement Transducers are "digits". Calculation of digits is based on the following
equation;
To convert digits to displacement the following equation applies;
Where;
R 1 is the current reading.
R 0 is the initial reading, usually obtained at installation (see section 2.5).
G is the calibration factor, usually millimeters or inches per digit.
For example, the initial reading, R 0 , at installation of a displacement transducer is 6783
digits. The current reading, R 1 , is 7228. The calibration factor, G, is 0.011906 mm/digit.
The deformation change is;
Note that increasing readings (digits) indicate increasing extension.
To convert to other engineering units refer to Table 2
From
Inches
To
Inches
Feet
0.0833
Millimeters
Centimeters
Meters
0.0254
2
1
Digits
Period
Equation 1 - Digits Calculation
D uncorrected = (R 1 - R 0 ) G
Equation 2 - Displacement Calculation
D = (7228 6783) 0.011906 = +5.3 mm
Feet
1
12
1
25.4
304.8
2.54
30.48
0.3048
Table 2 - Engineering Units Conversion Multipliers
2
Hz
3
or
10
Digits
1000
Millimeters
Centimeter
0.03937
0.003281
0.03281
1
0.10
0.001
Meters
s
0.3937
39.37
3.281
10
1000
1
100
0.01
1
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