Leica Geosystems Leica DISTO Pro - Manual (Page 58)

60 DISTO™ pro 4 / pro 4 a-1.0.0en English
en
n ... number of measurements
x
i
... individual value of a series
of measurements
... mean value of a series of
measurements
Calculation using the program Excel:
On the Insert menu, choose
Functions
Select category: Statistics and
Function:STABW within the Function
Assistant.
Depending on the version of
Excel and the language
used, the names of the menu may
vary.
Remarks on Measuring Accuracy
Both references (*, **) relate
to the technical data on the
previous page.
*The measuring accuracy
corresponds to the ISO-
recommendation ISO/R 1938-1971
with a statistical confidence level of
95% (i.e. ± twice the standard
deviation).The typical measuring
accuracy relates to average
conditions for measuring within the
specified range.
Measurement accuracy is not valid
for
• basic functions (except stake outs),
• calculation,
• continuous measurement (tracking).
The maximum measuring error relates to
unfavourable conditions such as:
• highly-reflecting surfaces (e.g.
reflector tapes),
• operating at the limits of the
permitted temperature range,
adaption to ambient temperature
interrupted (page 54)
• very bright ambient conditions,
strong heat shimmer and can be up
to ± 5 mm (twice the standard
deviation).
** At long range ± 30 ppm (± 3 mm/
100 m) plus short range error.
Range increases, the better the
laserlight is reflected from the target
area (diffuse, not reflective), and the
brighter the laserpoint is compared to
the surrounding luminosity (indoors,
dawn).
From approx. 40 - 50 m use target
plate, brown side.
Possible method of calculating
the standard deviation s:
When using a computer with a
statistical function or if you use the
program Excel, you can calculate the
mean value and the standard
deviation s directly from the 10
measured values.
Formula for the standard deviation
s:
Accuracy tests on the DISTO for
users certified to ISO 900...
You can perform your own accuracy
tests on the DISTO to meet the
requirements of ISO 900... for
measuring equipment.
Take a fixed, invariable, and
conveniently accessible distance of
about 1m to 10m, such as the width
of a window opening or of a room.
Measure it ten times.
Determine the magnitude of this
distance with a means of measurement
that is monitored by a national,
accredited calibration institute
(traceability back to national
standards).
Determine the amount that the
measurements vary from the nominal
distance, and compute the standard
deviation.
Record the standard deviation and
set a date for the next test.
Accuracy Tests