Specifications

13. Calibrating for Digital Measurement
USN52 L Operating Manual Page 79
11. Adjust the MTL VEL until the displayed S= value matches
the thickness (or flaw distance) of test block:
12. Optimize the echo that represents the lower end of the ex-
pected measurement range. Assure that the correct echo
appears within the gate and exceeds threshold level. If nec-
essary, adjust GAIN.
NOTE: If you are using multiple backwall echoes to cali-
brate, adjust a-START to the left so that the multiple that
represents the lower limit of the measurement range is the
first echo in the gate.
13. While the probe is coupled, adjust ZERO until the displayed
S= value matches the known thickness (distance) of the test
block:
NOTE: Adjusting ZERO changes the horizontal position of
displayed echoes (and DAC/TCG curve). It has no effect
on gate position or DELAY setting.
14. Repeat steps 6 through 13 until no further calibration is
needed.
15. Recheck the position and width of the gate to assure that
echo signals from the smallest and greatest expected mea-
surements will occur within the gate. If necessary, adjust a-
START and a-WIDTH until these conditions are met.
Below is a typical A-scan and measurement line display for 0 TO
1st measurement with a contact probe.
The USN52 L is now calibrated and ready to perform thickness or
distance measurements, within the calibrated range, on parts of
the same material, velocity of sound, and temperature as that of
the test block. S= values displayed represent the distance be-
tween the manually set zero point and the first echo signal within
the gate that exceeds threshold level.