Sokkia CX-101 Service Manual page 91

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Precaution when performing resection
In some cases it is impossible to calculate the coordinates of an unknown
point (instrument station) if the unknown point and three or more known
points are arranged on the edge of a single circle.
An arrangement such as that shown below is desirable.
It is sometimes impossible to perform a correct calculation in a case such
as the one below.
When they are on the edge of a single circle, take one of the following
measures.
(1) Move the instrument station
as close as possible to the
center of the triangle.
(2) Observe one more known
point which is not on the circle
(3) Perform a distance
measurement on at least one
of the three points.
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• In some cases it is impossible to calculate the coordinates of the instrument
station if the included angle between the known points is too small. It is difficult
to imagine that the longer the distance between the instrument station and the
known points, the narrower the included angle between the known points. Be
careful because the points can easily be aligned on the edge of a single circle.
13. SETTING INSTRUMENT STATION
: Unknown point
: Known point
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