Sokkia SDL30 Operator's Manual page 28

The forward and backward movement with respect to vertical position
A should be equal and not in excess of 5 to 10°.
Procedure
No good
Vertical
1 Turn the power switch on.
2 Set measuring mode to "Waving".
(see "16.1 Measuring Mode")
3 Focus on the staff.
4 Wave the
forwards (5 to 10°) through the
vertical
should be equivalent to 3 passings of
the staff through the vertical position
in approximately 3 seconds.
OK
No good
staff backwards
position. Waving
and
speed
27