Checkline TI-MVX - Manual (Page 33)

The One Point calibration is the simplest and most commonly used calibration
method -optimizing linearity over large ranges. The Two Point calibration allows
for greater accuracy over small ranges by calculating the probe zero and veloci-
ty. The TI-MVX provides four simple methods for setting the sound-velocity out-
lined below:
Calibration to a known velocity
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 CAL menu is highlighted and displaying
the submenu items.
2) Use the UP and DOWN arrow keys to scroll
through the sub menu items until VELOCITY is
highlighted.
3) Press the ENTER key to display the Digits Edit
Box.
4) Press the UP and DOWN arrow keys to scroll the highlighted value.
5) Press the LEFT and RIGHT arrow keys to scroll the digit locations.
6) Repeat steps 4 & 5 until the velocity number is correctly displayed.
7) Press the OK key to set the velocity and return to the menu screen, or ESC to
cancel entering the velocity.
8) Finally, press the MEAS key to return to the measurement screen and begin
taking readings.
One Point Calibration
Note: Be sure that a probe zero has been done
prior to performing this calibration procedure.
1) Physically measure a location on the sample to
be measured using a set of calipers or a digital
micrometer. Note: It’s always best to calibrate on
thickest location on the sample, rather than on the
thinnest location, as the percentage error is much
less with respect to the TI-MVX’s resolution of
+/-.001” (0.01mm).
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Adjusting the Gain using the Tabbed Menus
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 highlight-
ed.
3) Press the LEFT and RIGHT arrow keys to scroll
the value. When the correct Gain is being displayed,
proceed to step 8.
4) Alternatively, press the ENTER key to display the Digits Edit Box.
5) Press the UP and DOWN arrow keys to scroll the highlighted value.
6) Press the LEFT and RIGHT arrow keys to scroll the digit locations.
7) Repeat steps 5 & 6 until the Gain value is correctly displayed.
8) Press the OK key to set the Gain and return to the menu screen, or ESC to
cancel entering the Gain.
9) Finally, press the MEAS key to return to the measurement screen and begin
taking readings.
7.5 Threshold
The Threshold is the level (sensitivity) of the signal amplitude required to trigger
the thickness reading. This level can be used in conjunction with the gain.
Example: suppose the user can visually see a potential flaw on the display, but
the TI-MVX is not detecting on the flaw because the Gain is too low, or the
Threshold to high. The Threshold level can be decreased (lower sensitivity) in
order to detect signals with lower amplitudes. This will allow the amplitude from
the reflection of the flaw to reach and exceed the Threshold level, and enable
the TI-MVX to detect on the flaw or defect. This can also be accomplished by
increasing the Gain, allowing the signal to exceed the current Threshold level.
Lowering the Threshold (increases sensitivity), and raising the Threshold
decreases the sensitivity respectively.
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