Checkline TI-CMXDL - Manual (Page 32)

7.0 U SING THE D IGITS AND B-S CAN D ISPLAYS
A key feature of the TI-CMXDL is the ability to toggle between two different display options,
Digits and B-Scan. The Digits view provides the user with a large digital readout of the thickness.
Both views also include a scan bar features that uses a bar graph to indicate thickness. The
Scan bar can be very handy while scanning a tank or pipe wall by graphically displaying
deflections from pits or internal flaws, rather than having to constantly watch for changes in
the digital readout. It’s just another visual aid to alarm the user when something out of the
ordinary has been detected.
The B-Scan display is also very useful when scanning surfaces and viewing the cross section of
the test material. It provides a convenient way of visually profiling, or drawing a picture of, the
blind surfaces during a scan. The B-Scan display is also equipped with a scan bar representing the
overall thickness. Once again, the scan bar gives the user a visual indication when a flaw or
defect has been passed over during the scan process. The scan bar will deflect off of the defect
and return back to the overall thickness. In this chapter we’ll outline some of the fine adjustment
features of the TI-CMXDL. We’ll take a better look at these options in this chapter.
NOTE: In order to recall and use the new adjustments made to the TI-CMXDL at a later time,
the
user must save the modified settings in one of the setup locations. Refer section 11.0 for more
information on setups.
7.1 Display Views
DIGITS
The Digits view is a basic digital
thickness gauge look and feel. The
larger digits make it much easier for
the operator to monitor the thickness
readings. The Scan Bar has also been
added to the Digits view to provide
the user with yet another visual tool
for easily monitoring changes in
thickness readings due to internal
flaws or defects.
The following is a list of the viewable
features on the display:
A. Repeatability/Stability Indicator – This indicator should be commonly used in
conjunction with the digital thickness values displayed. When all the vertical bars
are fully illuminated and the last digit on the digital thickness value is stable, the
TI-CMXDL is reliably measuring the same value 3 to 200 times per second, depending
on which measurement mode and features are enabled.
B. Battery Icon – Indicates the amount of battery life the TI-CMXDL has remaining.
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7.4 Gain
The gain, or amplification of the return echoes, can be adjusted in the TI-CMXDL to
accommodate a variety of applications. The setting of the gain is crucial in order to obta
valid readings during the measurement process. Too much gain may result in erroneous
measurements, by detecting on noise rather than the actual material back wall itself. Not
enough gain may result in intermittent detection. It may also result in lack of detection o
internal flaws, pits, or porosity. The gain can easily be compared to the volume control o
home stereo system. If you turn it up too much, you can’t hear the music clearly. If it’s
turned down too much, you can’t hear it at all.
The TI-CMXDL has five gain settings (VLOW, LOW, MED, HI, VHI). The gain range i
42dB – 50dB in 2dB increments. Note: The TI-CMXDL has been optimized for the ME
gain setting for all common applications. It should be operated in this mode as standard.
However, some applications may require the lower or higher gain settings. When? The l
settings may be necessary for noisy or granular cast materials. How do I know when to
lower the gain? If the reading becomes sporadic and won’t settle down or resolve on a
thickness value, the user can assume that the material is either very noisy aluminum, or
granular cast iron. This would be a good time to change the TI-CMXDL to lower gain s
ting and see if the reading settles down and become stable.
How do I know when to increase the gain? Often times the user will be trying to measur
material that is hard to penetrate or pass sound through. This may be due to the material
type, or overall thickness of the material. When a material is hard to pass sound through
because of the thickness or general make-up, it would be a good time to consider switch
the TI-CMXDL into a higher gain setting. Another example might be the need to increas
overall sensitivity for locating fine pits or flaws. In any case, the selectable gain settings
offer the user some additional options to resolve and overcome application issues.
Note: When the echo-echo thru-paint measurement mode is selected, the manual gain fe
ture is disabled and grayed out in the menu items. In this mode, the TI-CMXDL switche
to an automatic gain mode (AGC) that optimizes the gain setting automatically in the ha
ware of the TI-CMXDL.
The procedures to adjust the Gain are outlined below:
1. Press the MENU key once to activate the menu items tab.
Press the MENU key multiple times to tab right, and the
ESC key multiple times to tab left, until the TUNE menu is
highlighted and displaying the submenu items.
2. Use the UP and DOWN arrow keys to scroll through the sub
menu items until GAIN is highlighted.
3. Press the LEFT and RIGHT arrow keys to scroll the value.
When the correct Gain is being displayed, press the MEAS
key to return to the measurement screen and begin taking
readings.
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