Geokon 1300, Instruction Manual

Page: 13 / 22

7
4. DATA REDUCTION
4.1 Digits
The basic units utilized by Geokon for measurement and reduction of data from the vibrating
wire displacement transducers used in the Model A-9 are "digits". The units displayed by the
GK-401, GK-402, and GK-403 in position "B" are digits. Calculation of digits is based on the
following equation;
Digits
Period






 

2
3
1
10
or
Digits
Hz

2
1000
Equation 1 - Digits Calculation
To convert digits to deformation the following equation applies;
D = (R
1
- R
0
)

G

F
Equation 2 - Deformation Calculation
Where;
D is the calculated deformation.
R
1
is the current reading.
R
0
is the initial reading usually obtained at installation (see section 2.4).
G is the calibration factor, usually in terms of millimeters or inches per digit taken
from the calibration sheet an example of which is shown in Figure 3
F is an engineering units conversion factor (optional), see Table 1.
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 1 - Engineering Units Conversion Multipliers
For example, the initial reading (R
0
) with no load on the pile of a Model A-9 transducer is 5102
digits. The reading with a 100 ton load on the pile, the current reading (R
1
), is 4523. The
calibration factor, G, is 0.0001755 inches/digit. The deformation change is;
D = (4523

5102)

0.0001755 =

0.1016 inches
Note that decreasing readings (digits) indicate compression.