Specifications

13. Calibrating for Digital Measurement
Page 96 USN52 L Operating Manual
If an error is detected when the calculations are performed, the
following message will be written to the screen and AUTOCAL will
be ended. “AutoCal error! Hit KEY to continue.”
If any of the following conditions are detected at calculation time,
an error message will be displayed and the calculations will be
aborted.
• S-REF1 equals S-REF2
• the second echo is the same as the first
• the calculated material velocity exceeds 9999m/sec
• the calculated material velocity is less then 1000m/sec
• the calculated zero exceeds 1600 µsec.
• the calculated zero is less than 1.4 µsec.
• the calculated values will not fit in the A-SCAN display
AUTOCAL records the time of flight for the two references and
calculates the material velocity and zero values according to the
following equations.
Material velocity = (2 * ( S − REF 2 − S − REF 1))
( TOF 2 - TOF 1)
zero = (( S − REF 2 * TOF 1)−( S − REF 1 * TOF 2))
( S − REF 2−S− REF 1)
S-ref = value entered by operator corresponding to test block
thickness.
TOF = time of flight recorded by the USN for the test block.
The zero and material velocity values calculated will be retained
after AUTOCAL until changed by the operator or until another
AUTOCAL is performed.