Spectra Precision Survey Pro v4.5 Ranger User Manual - Manual (Page 181)

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Leveling Fieldwork
Leveling is one of three possible surveying modes that can be used
with Survey Pro.
Leveling mode in Survey Pro can only be used after purchasing and
registering the Leveling Module. (See Page 4 for more information on
registering modules.) Once registered, level loops and the 2 peg test
can be performed.
Leveling data collection is organized into loops. A level loop is a
series of level measurements that start with a backsight on a known
point with a valid elevation. This point is referred to as the Starting
Benchmark. The level loop is closed with a foresight to another
known point, called the Closing Benchmark. A level loop can close on
the starting benchmark or a different point with a valid elevation.
A level loop can have two states: open and closed. Once a new loop is
created, it is automatically opened. It will remain open until you
decide to close the loop. A level loop is closed after the shot is taken
to the closing benchmark.
Level loops are stored within the current raw data and job files,
which can contain any number of level loops.
Any open loop can be selected from the current job as the active loop
for data collection. Once a loop is closed, it cannot be reopened for
data collection and can only be viewed or adjusted.
Key Terms
Level Loop: A level loop is a series of data collection observations
where a known elevation is initially recorded and used to precisely
determine the elevation at other locations. A level loop is usually
closed to the same benchmark where the loop was started, but can
also be closed to any other benchmark with a known elevation.
Turning Point: An intermediate point used in a level loop that the
rod occupies that is not a benchmark. Turning points are not stored
in the job, they are not permanent marks on the ground, and only
exist while the rod occupies them during the foresight/backsight
measurements.