ISO 17123-1:2014

INTERNATIONAL ISO
STANDARD 17123-1
Third edition
2014-08-15
Optics and optical instruments —
Field procedures for testing geodetic
and surveying instruments —
Part 1:
Theory
Optique et instruments d’optique — Méthodes d’essai sur site pour les
instruments géodésiques et d’observation —
Partie 1: Théorie
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General metrological terms . 1
3.2 Terms specific to this part of ISO 17123 . 3
3.3 The term “uncertainty” . 5
3.4 Symbols . 6
4 Evaluating uncertainty of measurement . 8
4.1 General . 8
4.2 Type A evaluation of standard uncertainty . 9
4.3 Type B evaluation of standard uncertainty .18
4.4 Law of propagation of uncertainty and combined standard uncertainty .19
4.5 Expanded uncertainty .21
5 Reporting uncertainty .22
6 Summarized concept of uncertainty evaluation .22
7 Statistical tests .23
7.1 General .23
7.2 Question a): is the experimental standard deviation, s, smaller than or equal to a given
value σ? .23
7.3 Question b): Do two samples belong to the same population? .24
7.4 Question c) [respectively question d)]:Testing the significance of a parameter y .
k 24
Annex A (informative) Probability distributions .26
Annex B (normative) χ distribution, Fisher’s distribution and Student’s t-distribution .27
Annex C (informative) Examples .28
Bibliography .39
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 documents 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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 172, Optics and photonics, Subcommittee SC 6,
Geodetic and surveying instruments.
This third edition cancels and replaces the second edition (ISO 17123-1:2010).
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)
iv © ISO 2014 – All rights reserved

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 an International Standard (ISO document) 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.
INTERNATIONAL STANDARD ISO 17123-1:2014(E)
Optics and optical instruments — Field procedures for
testing geodetic and surveying instruments —
Part 1:
Theory
1 Scope
This part of ISO 17123 gives guidance to provide general rules for evaluating and expressing uncertainty
in measurement for use in the specifications of the test procedures of ISO 17123-2, ISO 17123-3,
ISO 17123-4, ISO 17123-5, ISO 17123-6, ISO 17123-7 and ISO 17123-8.
ISO 17123-2, ISO 17123-3, ISO 17123-4, ISO 17123-5, ISO 17123-6, ISO 17123-7 and ISO 17123-8 specify
only field test procedures for geodetic instruments without ensuring traceability in accordance with
ISO/IEC Guide 99. For the purpose of ensuring traceability, it is intended that the instrument be calibrated
in the testing laboratory in advance.
This part of ISO 17123 is a simplified version based on ISO/IEC Guide 98-3 and deals with the problems
related to the specific field of geodetic test measurements.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC Guide 99 and the following
apply.
3.1 General metrological terms
3.1.1
(measurable) quantity
property of a phenomenon, body or substance, where the property has a magnitude that can be expressed
as a number and a reference
EXAMPLE 1 Quantities in a general sense: length, time, temperature.
EXAMPLE 2 Quantities in a particular sense: length of a rod.
3.1.2
value
value of a quantity
quantity value
number and reference together expressing the magnitude of a quantity
EXAMPLE Length of a rod: 3,24 m.
3.1.3
true value
true value of a quantity
true quantity value
value consistent with the definition of a given quantity
Note 1 to entry: This is a value that would be obtained by perfect measurement. However, this value is in principle
and in practice unknowable.
3.1.4
reference value
reference quantity value
quantity value used as a basis for comparison with values of quantities of the same kind
Note 1 to entry: A reference quantity value can be a true quantity value of the measurand, in which case it is
normally unknown. A reference quantity value with associated measurement uncertainty is usually provided by
a reference measurement procedure.
3.1.5
measurement
process of experimentally obtaining one or more quantity values that can reasonably be attributed to a
quantity
Note 1 to entry: Measurement implies comparison of quantities and includes counting of entities.
3.1.6
measurement principle
phenomenon serving as the basis of a measurement (scientific basis of measurement)
Note 1 to entry: The measurement principle can be a physical phenomenon like the Doppler effect applied for
length measurements.
3.1.7
measurement method
generic description of a logical organization of operations used in a measurement
Note 1 to entry: Methods of measurement can be qualified in various ways, such as “differential method” and
“direct measurement method”.
3.1.8
measurand
quantity intended to be measured
EXAMPLE Coordinate x determined by an electronic tacheometer.
3.1.9
indication
quantity value provided by
...