Download GTILT® PLUS - Geokon, Incorporated

GTILT USER’S MANUAL Version 3
Page 5-1
5.0 ENHANCING ACCURACY
Although not directly related to the functioning of GTILT, the following tips are offered to
help new inclinometer users achieve satisfactory results:
Try to install the casing as close to vertical as possible. This reduces the effects
of calibration changes which may affect the probe during the time interval
between readings. Even more important, it minimizes the effects of
accelerometer rotation errors.
Minimize rough handling of the probe, especially when turning it around for the
second pass, or when lowering it to the bottom for the second pass. Once you
have started to take readings in a casing, do not power down the probe until the
survey is complete.
If you have more than one inclinometer probe, try to schedule readings such that
the same probe is used for all sets of readings in a particular casing. You may
wish to use the same probe for all jobs in a given geographic area, if they tend to
be read during the same trip.
Be very sure always to read the cable depth marks relative to the same point
(usually the top of the casing). Using the wrong depth reference is a very
common cause of errors.
Avoid an extra site visit by making sure to use the correct pair of grooves. Since
marks on casing can wear off, mark the A0 groove by cutting a notch in it.
For best results, use the same cable or at least keep track of which cable you are
using on each occasion.
Do not forget to allow the instrument to warm up after it has been lowered to the
bottom of the casing, before taking any readings.
The very best results are achieved when the same technician is used for all
datasets.
When installing a new inclinometer, try to allow at least a few days for the grout
to set up and the casing to stabilize in the hole before taking the initial readings.
Take two initial sets and compare them on a CD plot. This helps avoid errors in
the critical initial set.