ISO 17123-6:2012
(Main)Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 6: Rotating lasers
Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 6: Rotating lasers
ISO 17123-6:2012 specifies field procedures to be adopted when determining and evaluating the precision (repeatability) of rotating lasers and their ancillary equipment when used in building and surveying measurements for levelling tasks. Primarily, these tests are intended to be field verifications of the suitability of a particular instrument for the immediate task at hand and to satisfy the requirements of other standards. ISO 17123-6:2012 differentiates between different measures of accuracy and objectives in testing, like repeatability and reproducibility (between-day repeatability), and gives a thorough assessment of all possible error sources.
Optique et instruments d'optique — Méthodes d'essai sur site des instruments géodésiques et d'observation — Partie 6: Lasers rotatifs
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17123-6
Second edition
2012-06-01
Optics and optical instruments — Field
procedures for testing geodetic and
surveying instruments —
Part 6:
Rotating lasers
Optique et instruments d’optique — Méthodes d’essai sur site des
instruments géodésiques et d’observation —
Partie 6: Lasers rotatifs
Reference number
ISO 17123-6:2012(E)
©
ISO 2012
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ISO 17123-6:2012(E)
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ISO 17123-6:2012(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 General . 2
4.1 Requirements . 2
4.2 Procedure 1: Simplified test procedure . 2
4.3 Procedure 2: Full test procedure . 2
5 Simplified test procedure . 4
5.1 Configuration of the test field . 4
5.2 Measurements . 5
5.3 Calculation . 5
6 Full test procedure . 5
6.1 Configuration of the test line. 5
6.2 Measurements . 6
6.3 Calculation . 7
6.4 Statistical tests .12
7 Influence quantities and combined standard uncertainty evaluation (Type A and Type B) .14
Annex A (informative) Example of the simplified test procedure .16
Annex B (informative) Example of the full test procedure .19
Annex C (informative) Example for the calculation of an uncertainty budget .23
Bibliography .27
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ISO 17123-6:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17123-6 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 6,
Geodetic and surveying instruments.
This second edition cancels and replaces the first edition (ISO 17123-6:2003), which has been technically revised.
ISO 17123 consists of the following parts, under the general title Optics and optical instruments — Field
procedures for testing geodetic and surveying instruments:
— Part 1: Theory
— Part 2: Levels
— Part 3: Theodolites
— Part 4: Electro-optical distance meters (EDM measurements to reflectors)
— Part 5: Total stations
— Part 6: Rotating lasers
— Part 7: Optical plumbing instruments
— Part 8: GNSS field measurement systems in real-time kinematic (RTK)
Annexes A, B and C of this part of ISO 17123 are for information only.
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ISO 17123-6:2012(E)
Introduction
This part of ISO 17123 specifies field procedures for adoption when determining and evaluating the uncertainty
of measurement results obtained by geodetic instruments and their ancillary equipment, when used in building
and surveying measuring tasks. Primarily, these tests are intended to be field verifications of suitability of a
particular instrument for the immediate task. They are not proposed as tests for acceptance or performance
evaluations that are more comprehensive in nature.
The definition and concept of uncertainty as a quantitative attribute to the final result of measurement was
developed mainly in the last two decades, even though error analysis has already long been a part of all
measurement sciences. After several stages, the CIPM (Comité Internationale des Poids et Mesures) referred
the task of developing a detailed guide to ISO. Under the responsibility of the ISO Technical Advisory Group
on Metrology (TAG 4), and in conjunction with six worldwide metrology organizations, a guidance document on
the expression of measurement uncertainty was compiled with the objective of providing rules for use within
standardization, calibration, laboratory, accreditation and metrology services. ISO/IEC Guide 98-3 was first
published as the Guide to the Expression of Uncertainty in Measurement (GUM) in 1995.
With the introduction of uncertainty in measurement in ISO 17123 (all parts), it is intended to finally provide a
uniform, quantitative expression of measurement uncertainty in geodetic metrology with the aim of meeting the
requirements of customers.
ISO 17123 (all parts) provides not only a means of evaluating the precision (experimental standard deviation)
of an instrument, but also a tool for defining an uncertainty budget, which allows for the summation of all
uncertainty components, whether they are random or systematic, to a representative measure of accuracy, i.e.
the combined standard uncertainty.
ISO 17123 (all parts) therefore provides, for defining for each instrument investigated by the procedures, a
proposal for additional, typical influence quantities, which can be expected during practical use. The customer
can estimate, for a specific application, the relevant standard uncertainty components in order to derive and
state the uncertainty of the measuring result.
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INTERNATIONAL STANDARD ISO 17123-6:2012(E)
Optics and optical instruments — Field procedures for testing
geodetic and surveying instruments —
Part 6:
Rotating lasers
1 Scope
This part of ISO 17123 specifies field procedures to be adopted when determining and evaluating the
precision (repeatability) of rotating lasers and their ancillary equipment when used in building and surveying
measurements for levelling tasks. Primarily, these tests are intended to be field verifications of the suitability of
a particular instrument for the immediate task at hand and to satisfy the requirements of other standards. They
are not proposed as tests for acceptance or performance evaluations that are more comprehensive in nature.
This part of ISO 17123 can be thought of as one of the first steps in the process of evaluating the uncertainty of a
measurement (more specifically a measurand). The uncertainty of a result of a measurement is dependent on a
number of parameters. Therefore this part of ISO 17123 differentiates between different measures of accuracy
and objectives in testing, like repeatability and reproducibility (between-day repeatability), and of course gives
a thorough assessment of all possible error sources, as prescribed by ISO/IEC Guide 98-3 and ISO 17123-1.
These field procedures have been developed specifically for in situ applications without the need for special
ancillary equipment and are purposefully designed to minimize atmospheric influences.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in probability
ISO 4463-1, Measurement methods for building — Setting-out and measurement — Part 1: Planning and
organization, measuring procedures, acceptance criteria
ISO 7077, Measuring methods for building — General principles and procedures for the verification of
dimensional compliance
ISO 7078, Building construction — Procedures for setting out, measurement and surveying — Vocabulary and
guidance notes
ISO 9849, Optics and optical instruments — Geodetic and surveying instruments — Vocabulary
ISO 17123-1, Optics and optical instruments — Field procedures for testing geodetic and surveying
instruments — Part 1: Theory
ISO 17123-2, Optics and optical instruments — Field procedures for testing geodetic and surveying
instruments — Part 2: Levels
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated terms (VIM)
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ISO 17123-6:2012(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3534-1, ISO 4463-1, ISO 7077,
ISO 7078, ISO 9849, ISO 17123-1, ISO 17123-2, ISO/IEC Guide 98-3 and ISO/IEC Guide 99 apply.
4 General
4.1 Requirements
Before commencing surveying, it is important that the operator investigates that the precision in use of the
measuring equipment is appropriate to the intended measuring task.
The rotating laser and its ancillary equipment shall be in known and acceptable states of permanent adjustment
according to the methods specified in the manufacturer’s handbook, and used with tripods and levelling staffs
as recommended by the manufacturer.
The results of these tests are influenced by meteorological conditions, especially by the temperature gradient.
An overcast sky and low wind speed guarantee the most favourable weather conditions. The particular
conditions to be taken into account may vary depending on the location where the tasks are to be undertaken.
Note should also be taken of the actual weather conditions at the time of measurements and the type of
surface above which the measurements are performed. The conditions chosen for the tests should match
those expected when the intended measuring task is actually carried out (see ISO 7077 and ISO 7078).
This part of ISO 17123 describes two different field procedures as given in Clauses 5 and 6. The operator shall
choose the procedure which is most relevant to the project’s particular requirements.
4.2 Procedure 1: Simplified test procedure
The simplified test procedure provides an estimate as to whether the precision of a given item of rotating-laser
equipment is within the specified permitted deviation, according to ISO 4463-1.
This test procedure is normally intended for checking the precision (see ISO/IEC Guide 99:2007, 2.15) of
a rotating laser to be used for area levelling applications, for tasks where measurements with unequal site
lengths are common practice, e.g. building construction sites.
The simplified test procedure is based on a limited number of measurements. Therefore, a significant standard
deviation and the standard uncertainty (Type A), respectively, cannot be obtained. If a more precise assessment
of the rotating laser under field conditions is required, it is recommended to adopt the more rigorous full test
procedure as given in Clause 6.
This test procedure relies on having a test field with height differences which are accepted as true values. If
such a test field is not available, it is necessary to determine the unknown height differences (see Figures 1 and
2), using an optical level of accuracy (see ISO 17123-2) higher than the rotating laser required for the measuring
task. If, however, a test field with known height differences cannot be established, it will be necessary to apply
the full test procedure as given in Clause 6.
If no levelling instrument is available, the rotating laser to be tested can be used to determine the true values
by measuring height differences between all points with central setups. At each setup, two height differences
have to be observed by rotating the laser plane by 180°. The mean value of repeated readings in both positions
will provide the height differences which are accepted as true.
4.3 Procedure 2: Full test procedure
The full test procedure shall be adopted to determine the best achievable measure of precision of a particular
rotating laser and its ancillary equipment under field conditions, by a single survey team.
Further, this test procedure serves to determine the deflective deviation, a, and both components, b and b , of
1 2
2 2
the deviation of the rotating axis from the true vertical, bb=+ b , of the rotating laser (see Figure 1).
1 2
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ISO 17123-6:2012(E)
a) Horizontal plane (top view)
b) Vertical plane through x′ (side view)
Key
1 inclined plane
2 cone axis
3 inclined cone
Figure 1 — Deflective deviations a and b (see Figure 5)
The recommended measuring distances within the test field (see Figure 3) are 40 m. Sight lengths greater than
40 m may be adopted for this precision-in-use test only, where the project specification may dictate, or where
it is determining the range of the measure of precision of a rotating laser at respective distances.
The test procedure given in Clause 6 of this part of ISO 17123 is intended for determining the measure of
precision in use of a particular rotating laser. This measure of precision in use is expressed in terms of the
experimental standard deviation, s, of a height difference between the instrument level and a levelling staff
(reading at the staff) at a distance of 40 m. This experimental standard deviation corresponds to the standard
uncertainty of Type A:
su=
ISO-ROLASISO-ROLAS
Further, this procedure may be used to determine:
— the standard uncertainty as a measure of precision in use of rotating lasers by a single survey team with
a single instrument and its ancillary equipment at a given time;
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ISO 17123-6:2012(E)
— the standard uncertainty as a measure of precision in use of a single instrument over time and differing
environmental conditions;
— the standard uncertainties as a measure of precision in use of several rotating lasers in order to enable a
comparison of their respective achievable precisions to be obtained under similar field conditions.
Statistical tests should be applied to determine whether the experimental standard deviation, s, obtained belongs
to the population of the instrumentation’s theoretical standard deviation, σ, whether two tested samples belong
to the same population, whether the deflective deviation, a, is equal to zero, and whether the deviation, b, of the
rotating axis from the true vertical of the rotating laser is equal to zero.
5 Simplified test procedure
5.1 Configuration of the test field
To keep the influence of refraction as small as possible, a reasonably horizontal test area shall be chosen. Six
fixed target points, 1, 2, 3, 4, 5 and 6, shall be set up in approximately the same horizontal plane at different
distances, between 10 m and 60 m apart from the instrument station S. The directions from the instrument to
the six fixed points shall be spread over the horizon as equally as possible (see Figure 2).
Key
S instrument station
1, 2, 3, 4, 5, 6 fixed target points
Figure 2 — Configuration of the test field for the simplified test procedure
To ensure reliable results, the target points shall be marked in a stable manner and reliably fixed during the test
measurements, including repeat measurements.
The height differences between the six fixed points, 1, 2, 3, 4, 5 and 6, shall be determined using an optical
level of known high accuracy as described in Clause 4.
The following five height differences between the t = 6 target points are known:
d
21,
d = t = 26, . (1)
d
tt, −1
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ISO 17123-6:2012(E)
5.2 Measurements
The instrument shall be set up in a stable manner above point S. Before commencing the measurements, the laser
beam shall become steady. To ensure that the laser plane of the instrument remains unchanged during the whole
measuring cycle, a fixed target shall be observed before and after each set, j, of measurements, (,j = 15., ).
Six separate readings, x to x , on the scale of the levelling staff shall be carried out to each fixed target point,
j,1 j,6
1, 2, 3, 4, 5 and 6. Between two sets of readings the instrument shall be lifted, turned clockwise approximately
70°, placed in a slightly different position and relevelled. The time between any two sets of readings shall be
at least 10 minutes.
Each reading shall be taken in a precise mode according to the recommendations of the manufacturer.
5.3 Calculation
The evaluation of the readings x for each set j is based on the following differences:
t
xx−
d jj,,21
j,,21
= − j ==15,., and t 26, . (2)
d
jt,,t−1 xx−
jt,,jt−1
respectively
dx= - x (3)
jj,,tj t-1
where
t is the number of the target point.
Calculating d , the mean of the differences d , the residual vector of the height differences in set j is obtained by
j
rd==-,dj 15., (4)
jj
Finally the sum of the residual squares of all five sets yields
5
2 T
∑=rr r. (5)
∑ j j
j=1
ν =×56()−=125 is the corresponding number of degrees of freedom.
2
∑r
s= = u (6)
ISO
v
where s is the experimental standard deviation and u the standard uncertainty (Type A) of a single measured
ISO
height difference, d , between two points of the test field. This represents in this part of ISO 17123 a
j,t,t−1
measure of precision relative to the standard uncertainty of a Type A evaluation. This value includes systematic
and random errors.
6 Full test procedure
6.1 Configuration of the test line
To keep the influence of refraction as small as possible, a reasonably horizontal test area shall be chosen. The
ground shall be compact and the surface shall be uniform; roads covered with asphalt or concrete shall be avoided.
If there is direct sunlight, the instrument and the levelling staffs shall be shaded, for example by an umbrella.
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ISO 17123-6:2012(E)
Two levelling points, A and B, shall be set up approximately 40 m apart. To ensure reliable results, the levelling
staffs shall be set up in stable positions, reliably fixed during the test measurements, including any repeat
measurements. The instrument shall be placed at the positions S1, S2 and S3. The distances from the
instrument’s positions to the levelling points shall be in accordance with Figure 3. The position S1 shall be
chosen equidistant between the levelling points, A and B (40/2 = 20 m).
Dimensions in metres
Figure 3 — Configuration of the test line for the full test procedure
6.2 Measurements
Before commencing the measurements, the instrument shall be adjusted as specified by the manufacturer.
For the full test procedure, i = 4 series of measurements should be performed. In each series, three instrument
setups S1, S2 and S3 are chosen, according to the configuration given in Figure 3. At any setup n = 4 sets of
readings are taken. Each set consists of two readings x , and x , namely to rod A and to rod B. After each
Aj Bj
set, the orientation of the instrument has to be changed clockwise about 90° (see Figure 4). Hence one series
consists of j = 3 × 4 = 12 readings for each rod. In order to ensure that the instrument deviation b is aligned
properly during the measurements, the instrument has to be oriented at the three positions S1, S2 and S3 in
the same direction and the sense of rotation has to be maintained.
With each new setup of the chosen reference direction (reference marks on the tripod head), the instrument
shall be relevelled carefully. If the instrument is provided with a compensator, care shall be taken that it
functions properly. It is recommended to assign the four orientations of the instrument on the ground plate.
The numbering of the 12 measurements can be represented for each measuring set as shown in Figure 4. All
readings shall be taken in a precise mode according to the recommendations of the manufacturer.
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ISO 17123-6:2012(E)
Figure 4 — Arrangement of measurements
6.3 Calculation
The possible deviations of a rotating laser may be modelled as shown in Figure 5.
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ISO 17123-6:2012(E)
Key
1 horizontal plane
2 inclined plane
3 inclined cone
4 radius of cone = 40 m
5 height of cone, a
Ο direction
Figure 5 — Model of instrument deviations
In order to create a horizontal sighting in the described measuring configuration, the readings at the levelling
staffs for selected sighting distances can be corrected in respect of the deviations a and b (see Table 1).
Table 1 — Corrections of the readings
Distance
Direction
14,6 m 20,0 m 54,6 m
1 0,365(a + b ) 0,500(a + b ) 1,365(a + b )
1 1 1
2 0,365(a + b ) 0,500(a + b ) 1,365(a + b )
2 2 2
3 0,365(a − b ) 0,500(a − b ) 1,365(a − b )
1 1 1
4 0,365(a − b ) 0,500(a − b ) 1,365(a − b )
2 2 2
th
From the observation formulae for the i series, the residuals, r to r , are obtained (see Table 2).
1 12
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ISO 17123-6:2012(E)
Table 2 — Observation formulae for the ith series
p = 2,0 p = 0,5 p = 0,5
rh=−bx−− x rh=+ab−− xx− rh=−ab−− xx−
() ()
()
11 B,11A, 51 B,5A,5 91 B,9A,9
rh=+bx−− x rh=+ab+− xx− r =−hab+− xx−
() () ()
22 B,2A,2 62 B,6A,6 10 2 B,10 A,10
rh=+bx−− x rh=+ab+− xx− r =−hab+− xx−
() () ()
31 B,3A,3 71 B,7A,7 11 1 B,11 A,11
rh=−bx−− x rh=+ab−− xx− rh=−ab−− xx−
() () ()
42 B,4A,4 82 B,8A,8 12 2 B,12 A,12
where
p is the weighting factor for one reading at the levelling staff (p = 1 for a sighting distance of 40 m);
h is the height difference between the levelling staffs B and A.
With 12 observations and four unknown parameters, h, a, b , b , we have an over-determined system, which
1 2
leads to a parametric adjustment. As the observation formulae are already linear, Table 2 can easily be
transferred in matrix notation:
rA = yx - (7)
where
r is the (12 × 1) residual vector of the r , j = 1, …, 12;
j
xx= - x is the (12 × 1) quasi-observation vector of the height differences, with
BA
x (12 × 1), reading vector x , j = 1, …, 12 of the levelling staff A and
Aj
A
x (12 × 1), reading vector x , j = 1, …, 12 of the levelling staff B;
Bj
B
y (4 × 1) is the vector of the unknown parameters.
With the design matrix
11 11 11 11 1111
00 00 11 11 -1 -1 -1 -1
T
A = (8)
-1 01 0 -1 01 0 -1 01 0
01 0-1 01 0-1 01 00-1
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ISO 17123-6:2012(E)
the solution vector of the unknown parameters is
h
a
TT--11 T
y = ==()APAA Px NA Px (9)
b
1
b
2
The weight matrix
p0
1
p = is given by diag (pj) = (2 2 2 2 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5) (10)
0p
12
Inserting Formulae (8) and (10) into Formula (9) the solution vector will be obtained finally by
h 1/61/6 1/61/6 1/224 1/24 1/24 1/24 1/24 1/24 1//241/24
a 00 00 1/81/8 1/81/8 1/81/8 1/81/8
y = = ⋅ x (11)
b -1/3 01/3 0 -1/120 1/12 0 -1/120 1/12 0
1
b 01/3 0-1/3 01/120 -1/12 01/120 -1/12
2
Regarding Formula (7) the experimental standard deviation for a sighting distance of 40 m is given by
T
rPr
s = with ν =−12 48= (12)
ν
From all series i = 1, …, 4 of observations we can derive the mean values of the parameters
h
4 4
a
1 1
yy== (13)
∑ i ∑
b
4 4
1
i=1 i=1
b
2
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ISO 17123-6:2012(E)
Finally we get the total deviation of the rotating axis from the true vertical of the rotating laser, referenced to a
sighting distance of 40 m:
2 2
bb=+ b (14)
1 2
With Formula (12) the overall experimental standard deviation of all series i = 1, …, 4 yields
4 4
2 T
sr Pr
∑∑i i i
i=1 i=1
s= = (15)
4 4
Herewith we can state the standard uncertainty (Type A) of a height difference, h, between the instrument level
and a levelling staff (reading at the levelling staff) referenced to a sighting distance of 40 m:
us= (16)
ISO-ROLAS
The experimental standard deviation for the parameters of all series can be calculated by
1
sy() = sdiagQ (17)
4
where
11/ 20 00
01/40 0
Q = (18)
00 16/ 0
00 01/6
Thus the standard deviations and the standard uncertainties (Type A), respectively, of the parameters are given by
su==()hs0,14 (19)
h
su==()as0,25 (20)
a
ss== ss= 0,20 (21)
bb b
12 12
Applying the law of variance covariance propagation on Formula (14), the experimental standard deviation of
the parameter b can be written as
1
22 22
s =+bs bs (22)
b 1 2
bb
12
b
Using Formula (21) leads to
1
2 22
s =+()bb ss= (23)
b 1 2
bb
12 12
b
and
su==()bs02, 0 (24)
b
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ISO 17123-6:2012(E)
6.4 Statistical tests
6.4.1 General
Statistical tests are recommended for the full test procedure only.
For the interpretation of the results, statistical tests shall be carried out using
— the experimental standard deviation, s, of a height difference, h, between the instrument level and a
levelling staff (reading at the levelling staff) referenced to a sighting distance of 40 m,
— the deflective deviation, a, referenced to a sighting distance of 40 m and its standard deviation, s , and
a
— the total deviation, b, of the rotating axis from the true vertical of the rotating laser referenced to a sighting
distance of 40 m and its standard deviation, s ,
b
in order to answer the following questions (see Table 3).
a) Is the calculated experimental standard deviation, s, for one reading at a levelling staff referenced to a
sighting distance of 40 m, smaller than the value, σ, stated by the manufact
...
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