ISO 17123-11:2025
(Main)Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 11: GNSS instruments
Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 11: GNSS instruments
This document specifies a field procedure for the verification that a given Global Navigation Satellite System (GNSS)-based system and measurement procedure meets a required measurement uncertainty at the location and time of interest. The field procedure uses three-dimensional coordinates which are compared to reference coordinates. It is designed to be applicable to the technically versatile geodetic and surveying GNSS systems on the market and can be used for any kind of GNSS-based applications to determine coordinates. It is independent of the technology used in the GNSS measuring instrument, the satellite data streams, and any correction data used. The procedure is applicable to GNSS instruments under operating condition in the field in such a way that the main parameters affecting the determination of coordinates are included in the result of the test. This document defines several delimitation criteria, which allows for versatile applicability. As a result, the verification procedure can be regularly performed in the field with limited economic impact.
Optique et instruments d'optique — Méthodes d'essai sur site des instruments géodésiques et d'observation — Partie 11: Instruments GNSS
General Information
Standards Content (Sample)
International
Standard
ISO 17123-11
First edition
Optics and optical instruments —
2025-07
Field procedures for testing
geodetic and surveying
instruments —
Part 11:
GNSS instruments
Optique et instruments d'optique — Méthodes d'essai sur site des
instruments géodésiques et d'observation —
Partie 11: Instruments GNSS
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 3
4.1 Symbols .3
4.2 Abbreviated terms .4
5 Delimitation . 4
5.1 Reason for delimitation .4
5.2 Quantitative delimitation by measurement uncertainty classes .4
5.3 Qualitative delimitation through multistage test procedure .5
5.4 Functional delimitation related to GNSS measuring instrument .6
5.5 Qualitative delimitation through the test criterion .6
5.6 Qualitative delimitation in the consideration of influencing factors .7
6 GNSS field test procedure . 8
6.1 Prerequisites for all procedure stages .8
6.2 Procedure stage 1 — Simplified GNSS field test procedures .9
6.2.1 Objective and scope .9
6.2.2 Test requirements .9
6.2.3 Test procedure.9
6.2.4 Calculation and interpretation .10
6.3 Procedure stage 2 — Full test procedure .10
6.3.1 Objective and scope .10
6.3.2 Test requirements .10
6.3.3 Test procedure.11
6.3.4 Calculation . 12
6.3.5 Interpretation and cause indications . 12
6.4 Procedure stage 3 — Extended test procedure . 15
7 Further recommendations in case of exceeding measurement errors .16
Annex A (informative) Procedure stage 3 — Extended test procedure — Methodology of a test
with isotropy or antenna property tests (example of antenna diagnostics).18
Annex B (informative) Examples of test procedures and their results . 19
Annex C (informative) Establishment of a reference point by long-term static GNSS
measurement .25
Annex D (informative) Exemplary assignment of applications to the measurement uncertainty
classes .27
Bibliography .28
iii
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 6,
Geodetic and surveying instruments.
A list of all parts in the ISO 17123 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
The ISO 17123 series 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.
These field procedures have been developed specifically for in situ applications without the need for special
ancillary equipment and are purposely designed to minimize atmospheric influences.
[1]
ISO 17123-8 provides a standard which exclusively covers Global Navigation Satellite System (GNSS) test
[1]
procedures for real-time kinematic applications. Since the creation of ISO 17123-8 , GNSS-based geodetic
measurement and instrumentation techniques have evolved in many ways:
[1]
— in addition to the classical real-time kinematic measurement procedures on which ISO 17123-8 is
based, other GNSS-based geodetic measurement procedures have become established;
— complementary to classical base-rover measurement arrangements and the instrument morphology by
means of separation of antenna and receiver, which was widely used at the time, versatile integrated
measurement instrument types are currently available;
— correction data services play an essential role in the analysis.
This document therefore has the following objectives:
— provision of GNSS field test procedures to achieve the highest possible reliability in the use of GNSS-
based geodetic measurement techniques;
— far-reaching consideration of technological advancements both in instrument technology and morphology
as well as in data streams;
— extensive independence from the accuracy class of the measuring equipment;
— consideration of the measuring equipment as a complete system;
— qualitative and quantitative multistage nature of the field test procedure in order to be able to meet
different requirement profiles;
— inclusion of the user’s expertise.
The implementation of these objectives is limited by the following framework conditions:
— a GNSS measuring instrument is not a measuring device in the narrower sense that can be tested
independently of external infrastructure on its own as well as without target specifications. Instead,
GNSS measuring instruments are subcomponents of an overall system;
— GNSS measuring instruments are perceived as black box systems. A large group of these systems is
designed by the manufacturer in such a way that no, or only little, influence can be exerted on important
instrument parameters;
— another group of GNSS measuring instruments follows an open-box strategy and allows a large number
of parameter settings in the positioning algorithm, the changes of which have a direct influence on the
determined position;
— GNSS-based measurement techniques are always based on an estimation algorithm, the result of which
depends on a very large number of possible influencing factors;
— the quality of satellite geodetic measurements and the positional accuracies that can be achieved with
them depend directly on the measurement conditions on site;
v
— a metrologically correct, and at the same time, procedurally simple consideration of a multitude of the
possible influencing factors on the achievable measurement accuracy is not possible according to the
current state of the art, in contrast to other geodetic instruments and measurement principles.
The field test procedure presented in this document therefore focuses on the visualization of a three-
dimensional coordinate, inherent to all GNSS measuring instruments, as the primary measurement result
value, which is compared to a nominal value. It is a daily performance verification independent of this specific
technique. More profound system verification requires the application of more specialized standards such
[1]
as ISO 17123-8 , which is not intended for high dynamic applications, e.g. autonomous driving, unmanned
aerial vehicle (UAV) applications.
vi
International Standard ISO 17123-11:2025(en)
Optics and optical instruments — Field procedures for testing
geodetic and surveying instruments —
Part 11:
GNSS instruments
1 Scope
This document specifies a field procedure for the verification that a given Global Navigation Satellite System
(GNSS)-based system and measurement procedure meets a required measurement uncertainty at the
location and time of interest.
The field procedure uses three-dimensional coordinates which are compared to reference coordinates. It is
designed to be applicable to the technically versatile geodetic and surveying GNSS systems on the market
and can be used for any kind of GNSS-based applications to determine coordinates. It is independent of the
technology used in the GNSS measuring instrument, the satellite data streams, and any correction data used.
The procedure is applicable to GNSS instruments under operating condition in the field in such a way that
the main parameters affecting the determination of coordinates are included in the result of the test. This
document defines several delimitation criteria, which allows for versatile applicability. As a result, the
verification procedure can be regularly performed in the field with limited economic impact.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9849 and ISO 17123-1 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
coordinate
one of a sequence of numbers designating the position of a point
Note 1 to entry: In a spatial coordinate (3.1) reference system, the coordinate (3.1) numbers are qualified by units.
Note 2 to entry: Coordinate in this document means a three-dimensional measured value in a coordinate system
determined by a measurement.
Note 3 to entry: Without limiting generality, the form of expression of coordinates in this document is by the
designation E (east), N (north), H (height).
[2]
[SOURCE: ISO 19111:2019 , 3.1.5, modified — Notes 2 and 3 to entry have been added.]
3.2
coordinate system
three-dimensional set of coordinates in which the global navigation satellite system (GNSS) (3.5) measuring
instrument calculates and displays the measured variables
3.3
position component
two-dimensional sub-system of the global navigation satellite system (GNSS) three-dimensional coordinate
system (3.2) comprising East and North coordinate (3.1)
Note 1 to entry: The GNSS coordinate (3.1) determined in perpendicular direction to the position component (3.3) is the
height component (3.4).
3.4
height component
global navigation satellite system (GNSS) (3.5) coordinate determined in perpendicular direction to the local
GNSS geoid surface
3.5
global navigation satellite system
GNSS
system consisting of several satellites in different orbital planes, which allow absolute navigation solutions
as well as highly precise (e.g. differential) positioning and broadcasting of time due to the global coverage
EXAMPLE 1 Global Positioning System (GPS) or Navigational Satellite Timing and Ranging – Global Positioning
System (NAVSTAR-GPS) - U.S. Department of Defense navigation system based on the constellation of usually more
than 24 satellites at an altitude of 20 200 km above the earth’s surface.
EXAMPLE 2 GLObal’naya NAvigationnaya Sputnikovaya Sistema (GLONASS) - Russia's GNSS based on the
constellation of approximately 24 satellites at an altitude of 19 100 km above the earth’s surface.
EXAMPLE 3 Galileo - GNSS organized by the EU and the European Space Agency. The system is planned to consist of
30 satellites at an altitude of 23 200 km above the earth’s surface.
EXAMPLE 4 Beidou - Satellite Navigation System operated by China. Satellites in medium earth orbit (22 000 km
above the earth’s surface) as well as in geosynchronous orbit (35 790 km above the earth’s surface) are used, where
the latter include satellites in both geostationary orbit and in inclined geosynchronous orbit.
EXAMPLE 5 Quasi-Zenith Satellite System (QZSS) – Satellite navigation system operated by Japan. The system is
compatible with GPS.
Note 1 to entry: GNSS includes all operating global navigation systems by satellite.
[SOURCE: ISO 9849]
3.6
global navigation satellite system measuring equipment
GNSS measuring equipment
sum of all devices and software applications required for the realization of a measuring point (3.11) and for
the determination of coordinates by means of satellite-based positioning
EXAMPLE GNSS measuring instrument (3.7), tripod, centring devices, data reception and communication modules.
3.7
GNSS measuring instrument
global navigation satellite system measuring instrument
measuring equipment for the determination of coordinates on the basis of satellite-supported positioning
Note 1 to entry: A GNSS measuring instrument (3.7) consists, e.g. of GNSS antenna, GNSS receiver, and field computer.
3.8
GNSS measurement procedure
global navigation satellite system measurement procedure
procedure including all satellite-based position determinations for the determination of coordinates in a
geodetic reference system
Note 1 to entry: Typical GNSS measurement procedures (3.8) are: Single Point Positioning (SPS), Precise Point
Positioning (PPP), Real-Time Kinematic (RTK), Network Real-Time Kinematic (NRTK).
3.9
dilution of precision
DOP
measure of the quality of the satellite geometry in a global navigation satellite system (GNSS) measurement
Note 1 to entry: The DOP value reflects the spatial distribution of the GNSS satellites during the measurement.
Note 2 to entry: Depending on the dimension of interest, the DOP value can be given as, e.g. vertical dilution of position
(VDOP, accuracy degradation in vertical direction), horizontal dilution of precision (HDOP, accuracy degradation in
horizontal direction), positional dilution of precision (PDOP, accuracy degradation in 3D), time dilution of precision
(TDOP, accuracy degradation in time), or geometric dilution of precision (GDOP, accuracy degradation in 3D and time).
3.10
antenna height
vertical distance of the antenna reference point to the point to be measured
3.11
measuring point
point from which or towards which a measurement is carried out
[3]
[SOURCE: ISO 7078:2020 , 3.6.50.]
3.12
reference point
measuring point (3.11) for which a reference value is known
4 Symbols and abbreviations
4.1 Symbols
Symbol Quantity Unit
U expanded measurement uncertainty m
x, y, z Cartesian coordinates m
E East coordinate in the GNSS three-dimensional coordinate system m
N North coordinate in the GNSS three-dimensional coordinate system m
H Height coordinate in the GNSS three-dimensional coordinate system m
L position component m
i, j running indices for measurement and measurement set number -
k running index for various antenna heights -
ϕ horizontal antenna orientation degree
h antenna height m
Symbol Quantity Unit
[a, b] closed interval from a included to b included -
[4]
ISO 80000-2
[4]
(a, b] left half-open interval from a excluded to b included ISO 80000-2 -
4.2 Abbreviated terms
max maximum
A, B, C, D measurement uncertainty classes
DOP dilution of precision
EPN European Permanent Network
IGS International GNSS Service
ITRF International Terrestrial Reference Frame
MPE Maximum Permissible Error
RINEX Receiver Independent Exchange Format
RTK Real-Time Kinematic
R Reference
mean value of quantity X (X=E, N, H, .)
5 Delimitation
5.1 Reason for delimitation
GNSS measurement procedures depend on a large number of influencing factors and prerequisites. For a
GNSS field test procedure to be standardised, the following delimitations are therefore to be made.
5.2 Quantitative delimitation by measurement uncertainty classes
The GNSS field test procedure includes:
— GNSS measuring instruments for determining coordinates with measurement uncertainties better than
5 m. The measurement uncertainties are classified according to Table 1.
Table 1 — Classification of measurement uncertainties in position (U ) and height coordinates
position
(U )
height
Dimensions in millimetres
Class U U
position height
A <10 <20
B [10; 30] [20; 50]
C (30; 200] (50; 200]
D (200; 5 000] (200; 5 000]
NOTE Exemplary assignment of applications to the measurement uncertainty classes are provided in Annex D.
The GNSS field test procedure excludes:
— GNSS measuring instruments for the determination of exclusively one- or two-dimensional coordinates;
— GNSS measuring instruments for the determination of exclusively non-static coordinate measuring, e.g.
velocity only.
5.3 Qualitative delimitation through multistage test procedure
The GNSS field test procedure includes a multistage GNSS field test procedure. It takes into account the area
of application of the GNSS measuring instrument, the test periodicity, and the measurement uncertainty
classes. It is subdivided according to Table 2, analogous to the structure of the ISO 17123 series.
Table 2 — Procedure stages of the GNSS field test procedure
Measurement
uncertainty class
Procedure stage Description
(see Table 1)
A B C D
1 Simple coordinate comparison (see 6.2) x x x
2 Qualified coordinate comparison (see 6.3) x x
Extended qualified comparison with concentration
3 on selected system parts (e.g. verification of anten- x
na calibration values). See 6.4.
The multistage nature of the GNSS field test procedure results as follows:
Procedure stage 1
— simplified test procedure with an evaluation of whether the measurement uncertainty of a coordinate is
within the selected measurement uncertainty class;
[5]
— without determination of standard uncertainties (according to ISO/IEC Guide 98-1 ; and
[6]
ISO/IEC Guide 98-3 )
— without restriction to a predefined GNSS measurement procedure.
Procedure stage 2
— complete test procedure with specification of defined measurement conditions;
— with references to influencing factors and preconditions to be observed (e.g. settings on the measuring
instrument, satellite visibility, DOP values, multipath effects);
— without restriction to a predefined GNSS measurement procedure.
Procedure stage 3 (diagnostic - not for conformance)
— extended test procedure for the best possible determination of the the magnitude of uncertainty
contributions from various components of the GNSS measuring instrument;
[5]
— with determination of standard uncertainties (according to ISO/IEC Guide 98-1 and
[6]
ISO/IEC Guide 98-3 );
— with restriction to a predefined GNSS measurement procedure;
— with instructions for improving the measurement uncertainties.
5.4 Functional delimitation related to GNSS measuring instrument
The GNSS field test procedure includes:
— the integral testing of the GNSS measuring equipment from measurement to portrayal of the coordinate
as depicted in Figure 1, including the GNSS measuring instrument used, accessories, measuring
instrument, firmware and application settings as well as correction and transformation data, including
any third party information or data streams used;
— the exclusive determination of measurement results in static measurement mode, using the measurement
settings used for the measurement task.
The GNSS field test procedure explicitly excludes:
— in procedure stages 1 and 2, the individual testing of components or parts of GNSS measuring instruments
(e.g. GNSS antenna only);
— the individual testing of accessories (e.g. tripod, scale, spirit level), the qualified examination of algorithms
and their parametrisations.
NOTE Contributions in dashed lines occur for specific GNSS measurement types, but not for all of them. Explicitly
not shown are influencing factors, e.g. multipath effects, atmosphere.
Figure 1 — Functional delimitation related to the GNSS measuring equipment
5.5 Qualitative delimitation through the test criterion
The GNSS field test procedure includes:
— the three-dimensional coordinates;
— the portrayal of the coordinates, limited to:
— three-dimensional Cartesian coordinates (x, y, z);
— three-dimensional ellipsoidal coordinates (longitude, latitude, ellipsoidal height);
— three-dimensional mapped coordinates (easting, northing, height);
— three-dimensional transformed coordinates;
— three-dimensional coordinate differences of the aforementioned coordinates (applies only to
procedure stages 2 and 3).
Without limitation of generality, the three-dimensional coordinates are used for better interpretation in the
tables and formulae in the expression form position (E, N) and height (H).
The GNSS field test procedure excludes:
— one- and two-dimensional coordinates;
— slope distances, plane distances and/or directions derived from coordinates;
— kinematic coordinates at timescales relative for the measurement.
5.6 Qualitative delimitation in the consideration of influencing factors
Coordinates determined from GNSS measurement methods are dependent on a variety of influencing factors.
These influencing factors are characterised by the following properties:
— the exact magnitude and impact of the influencing factors on the coordinates cannot be individually
determined;
— their influence is dependent on the choice of GNSS measurement procedure;
— the magnitude of their influence varies in relevance to the measurement procedure of the GNSS measuring
instrument used.
These properties mean that the effect of the influencing factors is part of the process of determining the
measured value within the GNSS measuring instrument and is thus included in the qualified assessment of
the measurement error as an unspecified influence quantity.
For this reason, the document specifies a predefined test environment in selected procedure steps. For the
evaluation of the measurement errors, significant influencing factors are named according to Table 3 and
their relevance for the measurement uncertainty classes A to D is specified.
Table 3 — Key influencing factors
Dimensions in millimetres
Procedure stage Measurement uncertainty class
1/2/3 A B C D
Maximum permissible error 10 to 30/ >30 to 200/ >200 to 5000/
<10/<20
U ∕ U 20 to 50 > 50 to 200 >200 to 5000
position height
Satellite orbit x x x x
Satellite clock x x x x
Space segment
Satellite geometry x x x x
Satellite antenna properties x x x
Ionospheric refraction x x x x
Tropospheric refraction x x x
Signal diffraction x x
Signal
Multipath effects x x x x
propagation
Shadow effects x x x x
Interference (e.g. with other radio
x x x x
sources)
Antenna near field x x
Antenna properties x x x
GNSS measuring
Antenna height x x x
instrument
Antenna centring x x
Receiver clock x x x x
TTabablele 3 3 ((ccoonnttiinnueuedd))
Procedure stage Measurement uncertainty class
1/2/3 A B C D
Maximum permissible error 10 to 30/ >30 to 200/ >200 to 5000/
<10/<20
U ∕ U 20 to 50 > 50 to 200 >200 to 5000
position height
Layup (pillar, tripod, pole) x x
Measuring and
Marking x x
reference point
Coordinate quality of reference point x x x x
Correction data quality x x x x
External
Coordinate quality of control points
information
x x
of geodetic reference frame
6 GNSS field test procedure
6.1 Prerequisites for all procedure stages
Before starting the GNSS field test procedure, it shall be checked whether the uncertainty class of the chosen
GNSS measurement equipment as well as the choice of the GNSS measurement procedure are suitable for the
intended surveying purpose.
Furthermore, it shall be checked and ensured that the coordinates of the reference point and those
determined using the measurement equipment for the measuring point are based on an identical coordinate
system in the same geodetic reference frame.
The quality and validity of the GNSS field test procedure can be improved by additional measures in addition
to the influencing factors listed in Table 3. These include instrumental transfer of measuring points to
the antenna reference point (e.g. by means of a pole) to a negligible error and the appropriate choice of
measurement duration, which should be based on the manufacturer’s recommendations.
The GNSS measurement equipment shall have an on-target and acceptable status of adjustment performed
according to the procedures specified in the manufacturer’s manual. Furthermore, all parts of the GNSS
measurement equipment, including accessories, shall be used as recommended by the manufacturer and the
normal operating parameters (e.g. maximum DOP value, specified transformation parameters, if applicable)
shall be set accordingly.
The results of the GNSS field test procedure are directly dependent on the location of the test. For this
reason, the GNSS field test procedure is preferably performed in at least one representative location within
the intended measurement area. If this is not possible, a reference point in proximity shall be used.
For the location of the test, the following minimum criteria shall be fulfilled for all procedure stages:
— permanently stable founded reference point. For project applications, this foundation shall apply at least
for the project duration in which the GNSS field test procedure is to be applied;
— design of either the measurement, or reference point, or both, as a ground point or measurement pillar;
— horizon clearance above at least 10° elevation;
— verifiable knowledge of the reference value in the desired coordinate system;
— the reference point may be either a reference point established, controlled and maintained by a public
surveying body or a reference point established and controlled by the user themselves;
— establishment and maintenance of a reference point requires advanced surveying capabilities which
are not covered by this document. In this case, the sufficiently good measurement uncertainty of the
reference point shall be determined and documented by a suitable procedure. An example for such a
procedure is provided in Annex C. The reference point shall be adequately monitored. In addition to
the mechanical and physical management of the reference point, coordinate changes due to crustal
movements shall be appropriately monitored;
— the number and the spatial arrangement of the reference points depend on the choice of the procedure stage.
The measurement uncertainty of the reference values of the reference point shall be no more than 33% of
maximum permissible error (MPE) being evaluated.
An MPE for the position and height components is defined for the measurement project in Table 4:
Table 4 — Definition of the maximum permissible errors
ΔL MPE in position component;
max
ΔH MPE in height component.
max
The instant and periodicity of the repetitions of the GNSS field tests depend in particular on the surveying
purpose, the size of the survey area, the procedure stage and the duration of the survey operation. The
minimum requirements that shall be met are:
— at the beginning in each new measurement area;
— after each change of transformation parameters;
— after every technical service or repair;
— after a fall, heavy impact or other suspected damage;
— after a longer period of non-use of the GNSS measuring equipment.
6.2 Procedure stage 1 — Simplified GNSS field test procedures
6.2.1 Objective and scope
The simplified test procedure provides the expert user with an assessment of whether the specified MPE
(see Table 4) can be met by the GNSS measurement equipment in combination with the GNSS measurement
procedure used at the location and time of the test.
6.2.2 Test requirements
The simplified test procedure is based on a target/actual comparison against one or more reference points
under measurement conditions, i.e.:
— using the same GNSS observation method as the one used in the measurement project;
— using the measurement duration used in the measurement project to determine a coordinate;
— using the GNSS measurement equipment used in the measurement project;
— using the geodetic reference frame used in the measurement project;
— using external information used in the measurement project, such as a GNSS correction data service;
— using the GNSS measuring instrument‘s standard procedure to determine the coordinates E , N , H in the
i i i
format of reference coordinates.
The simplified test procedure shall be performed at least once on the day of measurement.
6.2.3 Test procedure
Perform the test procedure as follows:
— trigger measurement 1 and determine coordinates E , N , H ;
1 1 1
— trigger measurement 2 and determine of coordinates E , N , H under the following conditions:
2 2 2
— maintain the position of use (e.g. no rotation of the pole or antenna);
— no additional time interval between the measurements;
— re-trigger the measurement process (e.g. for RTK measurements re-initialise phase ambiguities).
After performing measurements 1 and 2, the following coordinates are available:
E , N , H coordinates determined from measurement i (i= 1, 2);
i i i
E , N , H reference values according to the requirements of 6.1.
R R R
6.2.4 Calculation and interpretation
The measurement error of the coordinate is given by:
(1)
(2)
(3)
For further considerations, non-metric expression of the measurement error shall be converted into the
dimension metre.
The measurement error of the position component is calculated from:
(4)
The measurement error (ΔL , ΔH ) is placed in relation to the MPE (ΔL , ΔH ).
i i max max
If the following applies to the measurement error, the simplified test procedure is deemed to have been passed.
(5)
If Formula (5) is not fulfilled, the simplified test procedure is not passed. In this case, further investigations,
such as the full test procedure, are required (see subclause 6.3). Another consequence is that the selected
GNSS measurement equipment is not suitable for the purpose of surveying.
Annex B provides examples for the practical application of the simplified test procedure.
6.3 Procedure stage 2 — Full test procedure
6.3.1 Objective and scope
The full test procedure provides the expert user with a qualified statement as to whether the specified MPE
conforms with the selected GNSS measurement equipment in combination with the GNSS measurement
procedure used by it at the location and instant of the test. In case of non-conformity, assistance is provided
in localising the possible causes.
6.3.2 Test requirements
The full test procedure is based on a target or actual comparison against one or more reference points under
measurement conditions, i.e.:
— using the same GNSS observation method as the one used in the measurement project;
— using the measurement duration used in the measurement project to determine a coordinate;
— using the GNSS measurement equipment used in the measurement project;
— using the geodetic reference frame used in the measurement project;
— using external information used in the measurement project, such as a GNSS correction data service;
— using the GNSS measuring instrument‘s standard procedure to determine the coordinates E , N , H in the
i i i
format of reference coordinates.
The full test procedure shall be carried out at least before the start of a measurement project, and at least
annually if the GNSS measurement equipment is used regularly.
6.3.3 Test procedure
The test procedure for a measurement set is indicated in Figure 2.
Key
ϕ antenna orientation
h antenna height
j individual measurement number
Figure 2 — Principle of the four measurement steps within a measurement set of the full test
procedure
Perform the test procedure as follows:
— measure and determine the coordinates E , N , H in three sets (i= 1,2,3);
ij ij ij
— each set consists of four individual measurements ( j= 1,2,3,4);
— the individual measurements shall be carried out in succession according to Table 5 at antenna height h
k
and orientation ϕ of the GNSS antenna for k= 1, 2;
k
— the antenna height h shall be varied by at least 150 mm compared to h . The orientation varies by 180°.
2 1
As far as the GNSS measurement equipment allows, the antenna support (e.g. pole, adapter) shall be
included in the variations;
— the duration of each individual measurement shall be accumulated to the same measurement error as
defined for the measurement project;
— the individual measurements shall take place immediately in succession;
— no re-triggering of the measurement process shall take place within a set (e.g. no re-initialisation of
phase ambiguities in RTK measurements);
— the time interval between the sets shall be at least 20 min in order to take into account influential changes
in weather and satellite geometry;
— the measurement process shall be re-triggered between sets (e.g. re-initialisation of phase ambiguities
for RTK measurements).
Table 5 — Measuring sequence
Individual Antenna
Orientation
measurement height
E N H
ij ij ij
ϕ
k
ij h
k
11 h 0°
12 h 180°
Set 1
13 h 180°
14 h 0°
21 h 0°
22 h 180°
Set 2
23 h 180°
24 h 0°
31 h 0°
32 h 180°
Set 3
33 h 180°
34 h 0°
The interval between the different sets shall be at least 20 min.
6.3.4 Calculation
The measurement error is determined for each individual measurement in an identical manner to 6.2.4.
If the following applies to each measurement error, the full test procedure is deemed to have been passed.
(6)
Annex B provides examples for the practical application of the full test procedure.
If Formula (6) is not fulfilled and the GNSS measurement result does not pass the full test procedure, 6.3.5
provides assistance in locating the possible causes.
6.3.5 Interpretation and cause indications
6.3.5.1 General
From the individual measurements, indications of frequent causes that lead to the measurement error
being exceeded can be extracted. For this purpose, the measurement errors of the various individual
measurements are suitably grouped and evaluated.
NOTE An exemplary analysis according to 6.3.5 can be found in Clause B.3.
6.3.5.2 Influence of the transfer of the measuring point to the antenna datum point
A frequent cause of insufficient results can be found in the accessories used in the GNSS measuring
equipment to transfer the measuring point to the antenna datum point. Off-positions from the projection
of the measuring point, which may be due to the pole used, the optical plumb, the circular bubble or the
inclination sensor, can be identified by measuring in two positions between which the measuring equipment
is rotated by 180°.
Off-positions of the actual to the assumed antenna phase centre, which are larger in amount than the
measurement error and are not taken into account in the GNSS measurement equipment, are also revealed
by this measurement in two positions. On the other hand, off-positions of the actual to an antenna phase
centre calibrated in the position component, insofar as the calibration values in the GNSS measurement
equipment are not considered or the second antenna attitude is not considered correctly, are also detectable
by this measurement. These off-positions result in a double quantity when the antenna position is rotated
by 180°.
NOTE Each antenna has a different electrical centre and physical centre for each model. For high-accuracy
applications, respective orientation-dependent correction parameters have been determined in advance by the
manufacturer and are applied in post-processing. If the directions of both antennas are reversed as in 6.3.5 and the
internal system processing does not take the rotation into account, an error twice that of the phase centre offset (PCO)
can occur. This error is not a def
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