Specifications

13. Calibrating for Digital Measurement
USN52 L Operating Manual Page 95
When AUTOCAL is on, the MENU BOXES for the S-CAL Menu
will be modified by replacing the material velocity and zero menu
boxes with boxes as shown below.
GAIN
30.00 Db
CAL
a-START
1.000 in.
S-REF
1.000 in.
AUTOCAL Menu Boxes
When the user begins the AUTOCAL procedure, the CAL MENU
box appears as shown above. The second line of the CAL box
indicates current calibration step. It starts empty, meaning that the
AUTOCAL operation has not begun. A double press of corre-
sponding
keys for the CAL MENU box instructs the USN to
record the time of flight for the first reference. When the recording
is made, “REC 0” is replaced with “REC 1” to indicate that one
echo has been recorded. If no gate violation is occurring, the
AUTOCAL sequence will not advance to the next step. If more
than one violation exists, the first echo will be used.
After the first echo is recorded, the second S-REF must be en-
tered and the gate moved over the second echo. There must be
only one violation of the gate. Pressing the CAL
key will
record the second echo and display “REC 2.” At this point all
recording is complete. Another press of the key will record
the second echo and display “REC 2.” At this point all recording is
complete. Another press of the increment or decrement keys will
exit the AUTOCAL mode and perform the calculations and error
checking. If an error is detected, there will be no changes to the
material velocity or zero values. When the mode is exited, the
blank line will again appear under CAL. If at any point in the se-
quence, are simultaneously pressed, the mode will be ex-
ited, a blank line under CAL will be displayed, and no calibration
calculations will be performed. After a successful AUTOCAL op-
eration the material velocity will be in its fine range, in the basic
menu “mtl vel” rather than “MTL VEL” will appear. Upon comple-
tion of the AUTOCAL operation, the mode will be exited and the
special menus de-installed. The AUTOCAL mode will remain in
effect if the calibration results in an error message.