ISO 17123-8:2007

INTERNATIONAL ISO
STANDARD 17123-8
First edition
2007-09-15

Optics and optical instruments — Field
procedures for testing geodetic and
surveying instruments —
Part 8:
GNSS field measurement systems in real-
time kinematic (RTK)
Optique et instruments d'optique — Méthodes d'essai sur site des
instruments géodésiques et d'observation —
Partie 8: Systèmes de mesure GNSS sur site en temps réel
cinématique




Reference number
ISO 17123-8:2007(E)
©
ISO 2007

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ISO 17123-8:2007(E)
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©  ISO 2007
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ISO 17123-8:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 General. 2
4.1 Pre-amble. 2
4.2 Requirements . 2
4.3 The concept of the test procedures. 2
4.4 Procedure 1: Simplified test procedure. 3
4.5 Procedure 2: Full test procedure . 4
5 Simplified test procedure. 4
5.1 Measurements. 4
5.2 Calculation. 5
6 Full test procedure. 5
6.1 Measurements. 5
6.2 Calculation. 6
6.3 Statistical tests. 7
Annex A (informative) Example of the simplified test procedure. 10
Annex B (informative) Example of the full test procedure. 11

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ISO 17123-8:2007(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 17123-8 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 6,
Geodetic and surveying instruments.
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 instruments)
⎯ Part 5: Electronic tacheometers
⎯ Part 6: Rotating lasers
⎯ Part 7: Optical plumbing instruments
⎯ Part 8: GNSS field measurement systems in real-time kinematic (RTK)
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ISO 17123-8:2007(E)
Introduction
This part of ISO 17123 can be thought of as one of the first steps in the process of evaluating the uncertainty
of measurements (more specifically of measurands). The uncertainty of a result of a measurement is
dependent on a number of factors. These include among others: repeatability, reproducibility (between day
repeatability) and a thorough assessment of all possible error sources, as prescribed by the ISO Guide to the
expression of uncertainty in measurement (GUM).
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.

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INTERNATIONAL STANDARD ISO 17123-8:2007(E)

Optics and optical instruments — Field procedures for testing
geodetic and surveying instruments —
Part 8:
GNSS field measurement systems in real-time kinematic (RTK)
1 Scope
This part of ISO 17123 specifies field procedures to be adopted when determining and evaluating the
precision (repeatability) of Global Navigation Satellite System (GNSS) field measurement systems (this
includes GPS, GLONASS as well as the future systems like GALILEO) in real-time kinematic (GNSS RTK)
and their ancillary equipment when used in building, surveying and industrial measurements. Primarily, these
tests are intended to be field verifications of the suitability of a particular instrument for the required application
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.
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 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 17123-5, Optics and optical instruments — Field procedures for testing geodetic and surveying
instruments — Part 5: Electronic tacheometers
GUM, Guide to the expression of uncertainty in measurement, BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML,
1993, corrected and reprinted in 1995
VIM, International vocabulary of basic and general terms in metrology, BIPM, IEC, IFCC, ISO, IUPAC, IUPAP,
OIML, 1993
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3534-1, ISO 9849, ISO 17123-1,
ISO 17123-2, ISO 17123-5, GUM and VIM apply.
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ISO 17123-8:2007(E)
4 General
4.1 Preamble
The real-time kinematic positioning method is a relative measuring procedure using reference (base) and
moving (rover) receivers. For utilization of network RTK applications, a separate reference receiver is not
required. Both receivers perform the observations simultaneously and merge their results by wireless
transmission. Thus, the rover can display the instantaneous coordinates of the antenna in any appropriate
datum e.g. ITRF (International Terrestrial Reference Frame). For practical use they are transformed to
horizontal coordinates and ellipsoidal heights. Subsequently, only these types of coordinate are treated as
original observables.
4.2 Requirements
Before commencing surveying, it is important for the operator to ensure that the equipment, the GNSS
receiver and antenna, has sufficient precision for the task required.
The test should apply typically to a set of GNSS receivers and antennae listed in the manufacturer’s reference
manual. In case of using network RTK, consistency of antenna models (eg. antenna correction parameters)
shall be ensured.
The receiver, antenna and their ancillary equipment for rovers points shall be checked to be in acceptable
condition according to the methods specified in the reference manual.
The operator shall follow the guidelines in the manufacturer’s reference manual for positioning requirements
such as the minimum number of satellites, maximum PDOP (Position Dilution Of Precision) value, minimum
observation time and possibly other required pre-conditions.
The operator shall initialize the receiver by resetting its power prior to every measurement and collect the data
after the integer ambiguity fixing has been completed.
The following is the guideline for achievable centring precision expressed in standard deviation:
⎯ centering: 1 mm;
⎯ measuring the antenna height: 1 mm.
The results of the test are influenced by several factors, such as satellite configuration visible at the points,
ionospheric and tropospheric conditions, multipath environment around the points, precision of the equipment,
quality of the software running in the rover equipment or in the system generating the data transmitted from
the base point.
This part of ISO 17123 describes two different field procedures, namely the simplified test procedure and the
full test procedure, as given in Clauses 5 and 6 respectively. Therefore, the observation time of test procedure
shall be so arranged to cover such variations.
The operator shall choose the procedure that is most appropriate to the requirements of the project.
4.3 The concept of the test procedures
The test field consists of a base point and two rover points. The location of the rover points shall be close to
the area of the task concerned. The separation of two rover points shall be a minimum of 2 m and shall not
exceed 20 m. The positions of two rover points may be selected at convenience in the field (see Figure 1).
The horizontal distance and height difference between two rover points shall be determined by methods with
precision better than 3 mm other than RTK. These values are considered as nominal values and are used in
the first step of both test procedures. The horizontal distances and height differences calculated from the
measured coordinates in each set of measurements shall be compared with these values in order to ensure
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ISO 17123-8:2007(E)
that the measurements are free from any outlier. However, the nominal values are not used in the statistical
tests.
A series of measurements consists of five sets. Each set of measurements consists of successive
measurements at rover point 1 and 2.

Key
1 rover point
2 base point
a
Minimum 2 m; shall not exceed 20 m.
b
Corresponding distance according to the task concerned.
Figure 1 — Configuration of the field test network
The time lag between successive sets shall be approximately 5 min. This requirement makes the span of a
series of measurements to be about 25 min and five sets of measurements at both rover points shall be
uniformly distributed in this span. Due to the fact that the variation cycle of a typical multipath influence is
about 20 min, the measuring procedure will mostly cover the period of this influence factor.
The start time for each successive series shall be separated by at least 90 min. Thus, multiple series of
measurements tend to reflect influences such as changes in satellite configuration and variations in the
ionospheric and tropospheric conditions.
The standard deviations calculated over all measurements will therefore represent a quantitative measure of
precision in use including most of the typical influences in satellite positioning.
The simplified test procedure contains only one series of measurements and therefore only deals with the
outlier detection and with no statistical evaluation. Conversely, the full test procedure consists of three series
and additionally enables the estimation of standard deviations and statistical tests.
4.4 Procedure 1: Simplified test procedure
The simplified test procedure consists of a single series of measurements and provides an estimate as to
whether the precision of the equipment in use is within a specified allowable deviation.
The simplified test procedure is based on a limited number of measurements. Therefore, a significant
standard deviation cannot be obtained and the statistical tests are not applied. If a more precise assessment
of the equipment is required, it is recommended to adopt the more rigorous full test procedure as given in 4.5.
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ISO 17123-8:2007(E)
4.5 Procedure 2: Full test procedure
The full test procedure shall be adopted to determine the best achievable measure of precision of the
equipment in use.
The full test procedure consists of three series of measurements.
The full test procedure is intended for determining the experimental standard deviation for a single position
and height measurement.
Further, this procedure may be used to determine:
⎯ the measure of the precision of equipment under given conditions (including typical short and long term
influences);
⎯ the measure of the precision of equipment used in different periods of time or under different conditions
(multiple samples);
⎯ the measure of the capability of comparison between different precision of equipment achievable under
similar conditions.
Statistical tests shall be applied to determine whether the sample from the experiment belongs to the same
population as the one giving the theoretical standard deviation and to determine whether two samples from
different experiments belong to the same population.
5 Simplified test procedure
5.1 Measurements
For the simple test procedure, one series of measurements shall be taken, in which the observer shall obtain
five sets of measurements at two rover points. The sequence of the measurements is shown in Table 1 in
which the column labelled “Seq. No.” explicitly indicates the sequence of the measurement.
Table 1 — Sequence of the measurements for one series
Rover
Seq.
Series Set Measurement
point
No.
i j k x y h
1 1 1 1 x y h
1, 1, 1 1, 1, 1 1, 1, 1
2 1 1 2 x y h
1, 1, 2 1, 1, 2 1, 1, 2
3 1 2 1 x y h
1, 2, 1 1, 2, 1 1, 2, 1
4 1 2 2 x y h
1, 2, 2 1, 2, 2 1, 2, 2
5 1 3 1 x y h
1, 3, 1 1, 3, 1 1, 3, 1
6 1 3 2 x y h
1, 3, 2 1, 3, 2 1, 3, 2
7 1 4 1 x y h
1, 4, 1 1, 4, 1 1, 4, 1
8 1 4 2 x y h
1, 4, 2 1, 4, 2 1, 4, 2
9 1 5 1 x y h
1, 5, 1 1, 5, 1 1, 5, 1
10 1 5 2 x y h
1, 5, 2 1, 5, 2 1, 5, 2
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