Geokon GK-604D, User Manual

Page: 83 / 117

71
A.3.2 Measurement of “Face Error”
The “face error” is the reading shown by the inclinometer probe when it is
perfectly vertical. In practice , the easiest way to obtain the “face error” is to
run a normal inclinometer survey, with the two sets of readings at 180
°
, and
then to run a profile or deflection report. (see section C.2 and C.3, the column
labeled “Diff”) Examination of the data will reveal the average checksum
which is equal to twice the “face error.”
A.3.3 Setting of the “Face Error” to zero
There are three ways of setting the “face error” to zero. None of them are
necessary from the point of view of improving accuracy.
A.3.3.1 Mechanically
At the time of manufacture the electrical axis of the transducer is adjusted
by means of shims etc., until it points parallel to the axis of the
inclinometer probe. This method suffers from the disadvantage that if the
”face error” changes due to wear and tear on the probe and rough
handling, or shock loading of the transducer then the probe needs to be
returned to the factory for dismantling and re-adjustment.
A.3.3.2 Electrically
Electronic circuitry can be included in the probe so that the output of the
transducer can be adjusted to zero when the probe is vertical. The
disadvantage of this method is that it introduces electronic components
into the inside of the probe which may alter with time, temperature and
humidity and which, if the “face error” changes due to wear and tear or
rough handling, will require the probe to be dismantled and the electronic
circuitry readjusted. Also, this form of correction only masks the “face
error”. It does not really remove it and if the “face error” is very large the
calibration will be affected.
A.3.3.3 By software
The best way for setting the “face error” to zero is by applying an
automatic correction to the measured readings using the software
capabilities of the inclinometer readout box.