GE USM 36 Series Technical Reference And Operating Manual page 110

5 Operation
With thin wall thicknesses, the effect described above
leads to an echo amplitude drop which has to be espe-
cially taken into account with thicknesses <2 mm.
A stepped reference block having different wall thick-
nesses is required for calibration. The wall thicknesses
must be selected in such a way that they cover the ex-
pected measurement readings.
The use of the semi-automatic calibration is recom-
mended for calibration with a dual-element probe.
– Set the required test range.
– Vary the probe delay until the two calibration lines are
displayed within this range.
– Set the functions of pulser and receiver according to
the probe used and to the test application.
– Set the function TOF MODE (function group
GATE A) to FLANK.
– Select the gain so that the highest echo reaches ap-
proximately the full screen height.
5-34
– Set the gate threshold to the required height for mea-
suring the sound paths at the echo flanks.
– Switch to the function group AUTOCAL.
– Enter the two calibration lines (thicknesses) S-REF 1
and S-REF 2.
– Position the gate on the first calibration echo (function
A-START).
– Record the first calibration echo.
– After this, couple the probe to the calibration block
with the second calibration line and adjust the echo
height so that it is approximately as high as for the
first calibration echo.
– If necessary, shift the gate to the second calibration
echo.
– Record the second calibration echo.
Issue 2 (12/2013)
Calibrating the USM 36
USM 36