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7.2 Automatic Calibration of Probe Delay and Sound Velocity
In the
SETTING
menu, depress the
A.CALIB
key in order to activate auto-calibration
mode. The beginning of time base will be moved to the initial pulse, and range
and gate will be adapted accordingly automatically.
If operator doesn’t want to change any range and gate settings automatically, then
button may be used for switch directly to the Settings menu.
Notes: The example below describes Auto-calibration procedure with the Test Block
No.1 (EN 12223) and 45° angle probe.
This Auto-calibration procedure is applicable using any other sample with
known thickness (sound path), e.g. Test Block No.2 (EN 27963), and/or any
other probe (e.g. dual or single element straight probe) as well.
Position of echo flank within GATE1 will be used for Auto-calibration,
therefore it is advisable to adjust the echo height just above the GATE1
during measuring both S1 and S2 echoes, in order to minimize difference
between echo flank and echo peak readings.
1. Depress the A.CALIB button.
2. Adjust the VELOCITY to 3260 m/s
(shear waves in steel).
3. Adjust the time base range to approx.
250 mm.
4. Place transducer on calibration block at
the index point.
5. Swivel the transducer to peak the
echoes.
6. Adjust gate width to approx. 20 mm.
7. Adjust gate vertical position to approx. 50 %.
8. Adjust angle probe parameters (ANGLE, X-VALUE).
9. Depress “AUTOCALIB” button (left) to activate “S1 SET”. Set the distance
S1 = 100.0 mm
10. Depress “AUTOCALIB” button to activate “S2 SET” and the distance
S2 = 200.0 mm.
11. Move the gate over the first echo.
12. Depress “AUTOCALIB” button (right) to
activate “S1 MEASURE” and measure
position of first echo. If echo crosses the
gate,
then
“ECHO OK”
message
appears.