Olympus EPOCH 650 User Manual page 174

DMTA-10055-01EN, Rev. A, February 2015
If the EPOCH 650 is set to work in metric units, the calibration process is exactly the
same, except that the entries are in millimeters rather than inches.
To calibrate in echo-to-echo mode using a delay line transducer
1. Follow the initial setup procedure outlined in "Basic Setup" on page 143.
2. Connect the transducer to an appropriate cable, and then connect the cable to
either of the conventional transducer connectors at the top of the instrument.
With a zero offset of 0.000 µs, the excitation pulse (or main bang) should appear
on the left side of the screen.
3. Choose Basic > Zero, and then increase the value until the excitation pulse moves
off the left side of the screen and the interface echo from the end of the delay line
tip appears on the screen.
4. Verify that the echo represents the end of the delay by tapping your finger on the
end of the couplant-coated delay line.
This dampens the signal and the echo should jump up and down on the screen.
5. Choose Basic > Zero, and then increase the value to move this echo to the left side
of the screen so that it is barely visible.
At least two gates must be active to acquire an echo-to-echo measurement. Gate
Tracking must also be active.
6. Activate gate 1 and gate 2, by selecting Gate 1 > Status = On and Gate 2 > Status =
On.
7. Select Gate Setup > G2 Tracks = On so that gate 2 tracks gate 1.
For more information on gate tracking activation, see "Gate Tracking and Echo-to-
Echo Measurements" on page 130.
8. Select Auto Cal > Type = G2-1.
9. Couple the transducer to the calibration block.
For this example, the transducer is coupled to the 0.300 in. step.
10. Use the GATES key to position gate 1 so that the first back-wall echo from the
known thickness step exceeds the gate threshold.
11. Use the GATES key to position the separation of gate 1 and gate 2 so that the
second back-wall echo from the known thickness step exceeds the gate 2
threshold.
162 Chapter 9