Leica Geosystems TPS1100 Professional Series - User Manual - Manual (Page 85)

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TPS1100 - User Manual 2.2.1en System functions
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TCA and TCRA instruments are
motorized and equipped with
Automatic Target Recognition (ATR)
coaxially in the telescope. The EGL
guide light, mounted on the
telescope, is optional.
These instruments permit automatic
angle and distance measurements to
normal prisms and reduce the tedium
of precise visual sighting to prisms.
The prism is sighted with the optical
sight only. Initiating a distance
measurement will turn the instrument
with the help of the motors to sight
the prism-centre automatically.
The angles V and Hz are measured
to the centre of the prism at the
completion of the distance
measurement.
Automatic Target Recognition
As with all other instrument
errors, the collimation error
of the automatic target recognition
(ATR) must be redetermined
periodically (Refer to chapter
"Checking and Adjusting").
Reflections or foreign lights
(eg. from car headlights) can
affect the ATR-measurement.
Functionality
The built-in Automatic Target
Recognition ATR1 transmits a laser
beam. The reflected light is received
by the built-in camera (CCD). The
position of the received light spot with
respect to the centre of the CCD is
computed and the offsets are used to
correct the horizontal and vertical
angles. The offsets are also used to
control the motors which turn the
instrument so that the crosshairs are
centred on the prism.
In order to minimize the times for
measuring, the crosshair is not
moved to the exact centre of the
prism. The offset can be up to 5mm.
Then the Automatic Target
Recognition ATR1 measures the
offsets between the crosshair and
prism centre and corrects the Hz and
V angles accordingly.
Therefore the Hz and V angles are
measured to the prism-centre,
regardless of the crosshair pointing
precisely to the centre of the prism.