hydratight
138
SURFACE NOISE PROBLEM
NO GATE
W/GATE
The diagrams above can be illustrate a typical example of both cases. Let’s start
with the noise condition first. Refer to the
NO GATE
diagram:
(A)
refers to the
noise in front of the true reflection signal
(C)
. Notice that without a gate
activated, the
BOLTSCOPE PRO
is detecting on the noise
(A)
as shown at point
(B)
. However, the true measurement should be taken at point
(C)
. Given the
threshold and gain levels the
BOLTSCOPE PRO
is currently set to in the
NO
GATE
diagram, the amplitude from the noise is sufficient enough to cause the
BOLTSCOPE PRO
to detect, or measure the noise rather than the end of the
bolt
(C)
.
Now refer to the
W/GATE
diagram. The horizontal line at the top of
(D)
, is
GATE
. The start point of
GATE
has been adjusted to just beyond the noise
(A)
so that the
BOLTSCOPE PRO
ignores the noise and detects the true back wall
(C)
. Note: the
BOLTSCOPE PRO
will only detect on signals that are located
inside the dimensions of the
GATE (B)
. Therefore, the
BOLTSCOPE PRO
cannot see
(A)
at all, with respect to the starting point of the gate at
(B)
. Also
notice, the
THR
(threshold) level is the height of the distance
(D)
from the
baseline. Zero threshold is indicated by the bottom of the range
(D)
, and
THR: 6
(threshold) is indicated at the top of the range at
(D)
. Therefore, the vertical
height of
GATE1
is the
THR
(threshold) level. The threshold level can be
increased to decrease sensitivity, or decreased to increase sensitivity.
