FOCUS 35 TOTAL STATION USER GUIDE
6 –
Instrument Technology
87
Averaging Measurements to Reduce Sighting Errors
The Spectra Precision FOCUS 35 Total Station automatically reduces sighting errors caused by the
misalignment of the instrument to the target or by pole movement during measurement.
The following techniques can be used:
•
Use LockNGo Tracker. When LockNGo Tracker is enabled, the instrument automatically locks onto
and tracks the target. Manual sighting errors are reduced.
•
Automatically average angles during distance measurement. When measuring in Standard mode,
the instrument takes angle measurements while measuring the distance. Angles returned to the
instrument at 200 Hz, are averaged over this period to obtain an averaged angle measurement.
•
Use average measurement methods in the field software.
Distance Measuring Technology
Spectra Precision FOCUS 35 Total Stations are equipped with a combined distance unit. This means
that the instrument can measure to a prism or to normal surfaces (reflectorless mode).
The laser distance unit is based on the phase comparison method. The distance unit is coaxial with
the line of sight and transmits an intensity modulated optical measuring beam that is reflected by a
prism or scattered by a natural surface on which the beam is directed. The phase difference between
the transmitted light and the reflected received light is detected and represents the distance.
In prism mode, the unit operates as a fast and precise long-range distance meter. In reflectorless
mode, the unit transmits a collimated visible red laser beam to the target point and then calculates
the distance between the transmitted and the received light.
The distance unit software will detect erroneous single distance measurements such as those caused
by an obstruction passing through the measurement beam, and will ignore such readings in the
computation of the final distance.
The unambiguous range for distance measurement is as follows:
•
Prism mode - 7,350 m (24,114 ft)
•
Reflectorless mode - 1,100 m (3,609 ft)
Note –
Do not measure to a prism in reflectorless mode. Distances up to 1100 m (3,609 ft) are not
allowed because a Class 3 Laser is used for reflectorless distance measurement. For distances longer
than 1100m (3,609 ft), the instrument's distance accuracy is not guaranteed.
