14
3
Change the DB STEP value by repeatedly pressing
key or by turning the knob.
Note that DB STEP value can be quickly changed by repeatedly pressing the key
.
4.9 Auto Gain Feature
Use the Auto Gain function to automatically set the basic gain, so as to adjust the peak echo inside the
currently selected gate to a target height.
1
Set the target echo height using the AUTO function located in the FUNC submenu.
2
Press
GAIN
AUTO
to start the Auto Gain function. “AUTO-XX%” will be shown on the screen.
3
The Auto Gain function will end when the echo height reaches the target value. Or you can stop
the function by pressing
G
A
I
N
A
U
T
O
again.
4.10 Configuring the Gates
The gates monitor the range of the test object where you expect to detect a flaw. If an echo exceeds or
falls below the gate, an alarm signal is shown via the ALRM LED. The gate chooses the echo for the
digital time-of-flight or amplitude measurement.
The instrument has two gates: gate A and B. Gate A and B are independent of one another. Setting the
position and characteristics of the A- and B-Gates is the first step to configuring the instrument for flaw
detecting or material-thickness measurement. The GATE functions controls not only the location of the A
and B-Gates, but also the alarms and other features activated when an A-Scan signal crosses a specific
gate.
A-Scan signals crossing the A or B-Gate are evaluated for the purposes of flaw detection and
material-thickness evaluation. When the signal crosses the A or B-Gate, the maximum point (peak) of
the signal (in the specific gate) is used for evaluation purposes. The measured value is indicated on the
status line.
Selecting a Gate
Selecting a gate by using the GATE SEL
function in the GATE submenu.
You can also repeatedly press
A/B
to
switch the selected gate between Gate A
and Gate B.
The selected gate will be shown in solid
line. The unselected gate will be shown in
dashed line.
Positioning Gates
Use the following procedures to set the vertical and horizontal position of the A and B-Gates. Remember
that gate position has the following effects on instrument performance:
A-Scan echoes on the right side of the display screen represent features that occur at a greater
depth from the test-material surface than those on the left of the display screen. Therefore, moving a
gate to the right means that the gate is evaluating a deeper portion of the test material.
A wider gate will simply span the equivalent of more test-material depth
Increasing the vertical height (called threshold) of a gate means that only reflected signals of
sufficiently large amplitude will cross the gate.
Setting a Gate’s Starting Point
You can fix the starting point of the gates A or B within the display range.
1
Activate the GATE submenu (located in the BASIC menu).
2
Select the gate to be positioned using the GATE SEL function.
3
Select the gate START function and adjust the starting point by turning the knob. Increasing and
decreasing the value of the starting point moves the gate to the right and left, respectively.
