Additive Distance Constant - Sokkia 130R Series Operator's Manual

27.7

Additive Distance Constant

The additive distance constant K of the SET is adjusted to 0 before delivery.
Although it almost never deviates, use a baseline with a known distance precision
to check that the additive distance constant K is close to 0 several times a year
and whenever the values measured by the instrument begin to deviate by a
consistent amount. Perform these checks as follows.
• Errors in setting up the instrument and reflective prism or in sighting the target
will influence the additive distance constant. Be extremely careful to prevent
such errors when performing these procedures.
• Set up so that the instrument height and the target height are identical. If a flat
place is not available, use an automatic level to make sure the heights are
identical.
PROCEDURE Check
1. Find an area of flat ground where
two points 100m apart can be
selected.
Set up the Instrument at point A
and the reflective prism at point B.
Establish a point C half way
between points A and B.
2. Precisely measure the horizontal
distance between point A and
point B 10 times and calculate the
average value.
3. Place the SET at point C directly
between points A and B and set
up the reflective prism at point A.
4. Precisely measure the horizontal
distances CA and CB 10 times
each and calculate the average
value for each distance.
27. CHECKS AND ADJUSTMENTS
147