IEC 61280-4-2:2014

IEC 61280-4-2 ®
Edition 2.0 2014-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre-optic communication subsystem test procedures –
Part 4-2: Installed cable plant – Single-mode attenuation and optical return
loss measurement
Procédures d’essai des sous-systèmes de télécommunication à
fibres optiques –
Partie 4-2: Installations câblées – Mesure de l'affaiblissement de réflexion
optique et de l'affaiblissement des fibres unimodales

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IEC 61280-4-2 ®
Edition 2.0 2014-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre-optic communication subsystem test procedures –

Part 4-2: Installed cable plant – Single-mode attenuation and optical return

loss measurement
Procédures d’essai des sous-systèmes de télécommunication à

fibres optiques –
Partie 4-2: Installations câblées – Mesure de l'affaiblissement de réflexion

optique et de l'affaiblissement des fibres unimodales

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XC
ICS 33.180.01 ISBN 978-2-8322-1665-1

– 2 – IEC 61280-4-2:2014  IEC 2014
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, graphical symbols and abbreviations . 11
3.1 Terms and definitions . 11
3.2 Graphical symbols . 13
3.3 Abbreviations . 14
4 Measurement methods . 15
4.1 General . 15
4.2 Cabling configurations and applicable test methods . 16
4.2.1 Cabling configurations and applicable test methods for attenuation
measurements . 16
4.2.2 Cabling configurations and applicable test methods for optical return

loss measurements . 18
4.3 Overview of uncertainties . 18
4.3.1 General . 18
4.3.2 Test cords . 18
4.3.3 Reflections from other interfaces . 18
4.3.4 Optical source . 18
4.3.5 Output power reference . 19
4.3.6 Received power reference . 19
4.3.7 Mode field diameter variation . 19
4.3.8 Bi-directional measurements . 19
5 Apparatus . 19
5.1 General . 19
5.2 Light source . 19
5.2.1 Stability . 19
5.2.2 Spectral characteristics . 20
5.2.3 Launch cord . 20
5.3 Receive or tail cord . 20
5.4 Substitution cord . 21
5.5 Power meter – LSPM methods only. 21
5.6 OTDR apparatus . 21
5.7 Return loss test set . 22
5.8 Connector end-face cleaning and inspection equipment . 22
5.9 Adapters . 22
6 Procedures . 22
6.1 General . 22
6.2 Common procedures . 23
6.2.1 Care of the test cords . 23
6.2.2 Make reference measurements (LSPM and OCWR methods only) . 23
6.2.3 Inspect and clean the ends of the fibres in the cabling . 23
6.2.4 Make the measurements . 23
6.2.5 Make the calculations . 23
6.3 Calibration . 23

6.4 Safety . 24
7 Calculations . 24
8 Documentation . 24
8.1 Information for each test . 24
8.2 Information to be made available . 24
Annex A (normative) One-cord reference method . 25
A.1 Applicability of test method . 25
A.2 Apparatus . 25
A.3 Procedure . 25
A.4 Calculation . 26
A.5 Components of reported attenuation . 26
Annex B (normative) Three-cord reference method . 27
B.1 Applicability of test method . 27
B.2 Apparatus . 27
B.3 Procedure . 27
B.4 Calculations . 28
B.5 Components of reported attenuation . 28
Annex C (normative) Two-cord reference method . 29
C.1 Applicability of test method . 29
C.2 Apparatus . 29
C.3 Procedure . 29
C.4 Calculations . 31
C.5 Components of reported attenuation . 31
Annex D (normative) Optical time domain reflectometer . 32
D.1 Applicability of test method . 32
D.2 Apparatus . 32
D.2.1 General . 32
D.2.2 OTDR . 32
D.2.3 Test cords . 32
D.3 Procedure (test method) . 33
D.4 Calculation of attenuation . 34
D.4.1 General . 34
D.4.2 Connection location . 34
D.4.3 Definition of the power levels F and F . 35
1 2
D.4.4 Alternative calculation. 36
D.5 Calculation of optical return loss . 37
D.6 Calculation of reflectance for discrete components . 39
D.7 OTDR uncertainties . 40
Annex E (normative) Continuous wave optical return loss measurement – Method A . 41
E.1 Applicability of test method . 41
E.2 Apparatus . 41
E.2.1 General . 41
E.2.2 Light source . 41
E.2.3 Branching device or coupler . 41
E.2.4 Power meters . 42
E.2.5 Connector interface . 42
E.2.6 Low reflection termination . 42
E.3 Procedure . 42

– 4 – IEC 61280-4-2:2014  IEC 2014
E.3.1 Test set characterization. 42
E.3.2 Measurement procedure . 44
E.3.3 Calculations . 44
E.3.4 Measurement uncertainty. 45
Annex F (normative) Continuous wave optical return loss measurement – Method B. 46
F.1 Applicability of test method . 46
F.2 Apparatus . 46
F.2.1 General requirements . 46
F.2.2 Known reflectance termination . 46
F.3 Procedure . 46
F.3.1 Set-up characterization . 46
F.3.2 Measurement procedure . 47
F.3.3 Calculation . 48
F.3.4 Measurement uncertainty. 48
Annex G (informative) Measurement uncertainty examples . 49
G.1 Reduction of uncertainty by using reference grade terminations and related
issues . 49
G.1.1 Motivations for using reference grade terminations on test cords . 49
G.1.2 Adjusting acceptance limits to allow for different expected losses when
using reference grade and standard grade connectors . 49
G.2 Estimation of the measurement uncertainties . 51
G.2.1 Measurement uncertainty. 51
G.2.2 Uncertainty due to the instrument . 51
G.2.3 Uncertainty due to the source . 51
G.2.4 Uncertainty due to the device under test . 52
G.2.5 Example of uncertainty accumulation using a single power meter . 53
G.2.6 Example of uncertainty accumulation using two power meters . 54
Annex H (informative) OTDR configuration information . 55
H.1 Introductory remarks . 55
H.2 Fundamental parameters that define the operational capability of an OTDR . 56
H.2.1 Dynamic range . 56
H.2.2 Pulse width . 56
H.2.3 Averaging time . 56
H.2.4 Dead zone . 56
H.3 Other parameters . 56
H.3.1 Index of refraction . 56
H.3.2 Measurement range . 57
H.3.3 Distance sampling . 57
H.4 Other measurement configurations . 57
H.4.1 General . 57
H.4.2 Macro bend attenuation measurement . 57
H.4.3 Splice attenuation measurement . 58
H.4.4 Measurement with high reflection connectors or short length cabling . 58
H.4.5 Ghost . 60
H.5 More on the measurement method . 61
H.6 Bidirectional measurement . 62
H.7 OTDR bi-directional trace analysis . 63
H.8 Non recommended practices . 64
H.8.1 Measurement without tail cord . 64

H.8.2 Cursor measurement . 64
Annex I (informative) Test cord attenuation verification . 65
I.1 Introductory remarks . 65
I.2 Apparatus . 65
I.3 Procedure . 65
I.3.1 General . 65
I.3.2 Test cord verification for the one-cord and two-cord reference test
methods when using non-pinned/unpinned and non-plug/socket style
connectors . 66
I.3.3 Test cord verification for the one-cord and two-cord reference test
methods using pinned/unpinned or plug/socket style connectors . 67
I.3.4 Test cord verification for the three-cord reference test method using
non-pinned/unpinned and non-plug/socket style connectors. 68
I.3.5 Test cord verification for the three-cord reference test method using
pinned/unpinned or plug/socket style connectors . 70
Annex J (informative) Spectral attenuation measurement . 72
J.1 Applicability of test method . 72
J.2 Apparatus . 72
J.2.1 Broadband light source . 72
J.2.2 Optical spectrum analyser . 72
J.3 Procedure . 72
J.3.1 Reference scan . 72
J.3.2 Measurement scan . 73
J.4 Calculations . 73
Bibliography . 74

Figure 1 – Connector symbols . 13
Figure 2 – Symbol for cabling under test . 14
Figure 3 – Configuration A – Start and end of measured losses in reference test
method . 16
Figure 4 – Configuration B – Start and end of measured losses in reference test
method . 17
Figure 5 – Configuration C – Start and end of measured losses in reference test
method . 17
Figure 6 – Typical OTDR schematic . 21
Figure 7 – Return loss test set illustration . 22
Figure A.1 − One-cord reference measurement . 26
Figure A.2− One-cord test measurement . 26
Figure B.1 − Three-cord reference measurement . 27
Figure B.2 − Three-cord test measurement . 28
Figure C.1 − Two-cord reference measurement. 30
Figure C.2 − Two-cord test measurement . 30
Figure C.3 – Two-cord test measurement for plug-socket style connectors . 30
Figure D.1 − Test measurement for method D . 34
Figure D.2 − Location of the cabling under test ports . 35
Figure D.3 − Graphic construction of F and F . 36
1 2
Figure D.4 − Graphic construction of F , F , F and F . 37
1 11 21 2
– 6 – IEC 61280-4-2:2014  IEC 2014
Figure D.5 − Graphic representation of OTDR ORL measurement . 38
Figure D.6 − Graphic representation of reflectance measurement . 39
Figure E.1 – Return loss test set illustration . 41
Figure E.2 – Measurement of the system internal attenuation P . 43
ref2
Figure E.3 – Measurement of the system internal attenuation P . 43
ref1
Figure E.4 – Measurement of the system reflected power P . 43
rs
Figure E.5 – Measurement of the input power P . 44
in
Figure E.6 – Measurement of the reflected power . 44
Figure F.1 – Return loss test set illustration . 46
Figure F.2 – Measurement of P with reflections suppressed . 47
rs
Figure F.3 – Measurement of P with reference reflector . 47
ref
Figure F.4 – Measurement of the system reflected power P . 47
rs
Figure F.5 – Measurement of the reflected power . 48
Figure H.1 − Splice and macro bend attenuation measurement . 58
Figure H.2 − Attenuation measurement with high reflection connectors . 59
Figure H.3 − Attenuation measurement of a short length cabling . 60
Figure H.4 − OTDR trace with ghost . 61
Figure H.5 − Cursor positioning. 62
Figure H.6 – Bidirectional OTDR trace display . 63
Figure H.7 – Bi-directional OTDR trace loss analysis . 63
Figure I.1 − Obtaining reference power level P . 66
Figure I.2 − Obtaining power level P . 67
Figure I.3 − Obtaining reference power level P . 67
Figure I.4 − Obtaining power level P . 67
Figure I.5 − Obtaining reference power level P . 68
Figure I.6 − Obtaining power level . 68
Figure I.7 − Obtaining reference power level P . 69
Figure I.8 − Obtaining power level P . 69
Figure I.9 − Obtaining power level P . 70
Figure I.10 − Obtaining reference power level P . 70
Figure I.11 − Obtaining power level P . 71
Figure J.1 − Result of spectral attenuation measurement . 73

Table 1 – Cabling configurations . 16
Table 2 – Test methods and configurations . 17
Table D.1 – Typical launch and tail cord lengths . 33
(see NOTE 1)
Table G.1 – Expected loss for examples . 49
Table G.2 – Example of uncertainty accumulation using a single power meter . 53
Table G.3 – Example of uncertainty accumulation using two power meters . 54
Table H.1 – Example of effective group index of refraction values . 57

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE-OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 4-2: Installed cable plant –
Single-mode attenuation and optical return loss measurement

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61280-4-2 has been prepared by subcommittee SC86C: Fibre
optic systems and active devices, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition, published in 1999, and constitutes
a technical revision.
The main changes with respect to the previous edition are listed below:
– revision of optical time-domain reflectometer (OTDR) measurements;
– addition of optical return loss (ORL) measurements;
– addition of informative annexes on measurement uncertainties, OTDR configuration, test
cord attenuation verification and spectral attenuation measurement.

– 8 – IEC 61280-4-2:2014  IEC 2014
The text of this standard is based on the following documents:
FDIS Report on voting
86C/1238/FDIS 86C/1261/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61280 series, published under the general title Fibre-optic
communication subsystem test procedures, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
INTRODUCTION
This second edition of IEC 61280-4-2 for testing single-mode cable plant follows on from the
second edition of IEC 61280-4-1, dealing with multimode cable plants.
Cabling design standards such as ISO/IEC 11801 for commercial premises, ISO/IEC 24702
for industrial premises, ISO/IEC 24764 for data centres and ISO/IEC 15018 for residential
cabling contain specifications for this type of cabling. These standards support cabling
lengths of up to 2 km for commercial premises and data centres and up to 10 km for industrial
premises. ISO/IEC 14763-3, which supports these design standards, makes reference to the
test methods of this standard.
Various recommendations from ITU-T have requirements for longer distance applications
including short haul (40 km), long haul (80 km) and ultra long haul (160 km). The testing of
cable plant for these is covered in ITU-T Recommendation G.650.3, which makes reference to
the test methods of this standard.

– 10 – IEC 61280-4-2:2014  IEC 2014
FIBRE-OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 4-2: Installed cable plant –
Single-mode attenuation and optical return loss measurement

1 Scope
This part of IEC 61280 is applicable to the measurement of attenuation and optical return loss
of installed optical fibre cable plant using single-mode fibre. This cable plant can include
single-mode optical fibres, connectors, adapters, splices and other passive devices. The
cabling may be installed in a variety of environments including residential, commercial,
industrial and data centre premises, as well as outside plant environments.
This standard may be applied to all single-mode fibre types including those designated by
IEC 60793-2-50 as Class B fibres.
The principles of this standard may be applied to cable plants containing branching devices
(splitters) and at specific wavelength ranges in situations where passive wavelength selective
components are deployed, such as WDMs, CWDM and DWDM devices.
This standard is not intended to apply to cable plant that includes active devices such as fibre
amplifiers or dynamic channel equalizers.
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.
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
IEC 60825-2, Safety of laser products – Part 2: Safety of optical fibre communication systems
(OFCS)
IEC 60874-14-2, Connectors for optical fibres and cables – Part 14-2: Detail specification for
fibre optic connector type SC-PC tuned terminated to single-mode fibre type B1
IEC 61300-3-6, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-6: Examinations and measurements – Return loss
IEC 61300-3-35, Fibre optic interconnecting devices and passive components − Basic test
and measurement procedures − Part 3-35: Examinations and measurements − Fibre optic
cylindrical connector endface visual inspection
IEC 61315, Calibration of fibre-optic power meters
IEC 61746-1:2009, Calibration of optical time-domain reflectometers (OTDR) – Part 1: OTDR
for single-mode fibres
IEC TR 62627-01, Fibre optic interconnecting devices and passive components – Fibre optic
connector cleaning methods
3 Terms, definitions, graphical symbols and abbreviations
For the purposes of this document, the following terms, definitions, graphical symbols and
acronyms apply.
3.1 Terms and definitions
3.1.1
adapter
female part of a connector in which one or two plugs are inserted and aligned
[SOURCE: IEC TR 61931:1998, 2.6.4]
3.1.2
attenuation
measure of the reduction of optical power transmitted through the cabling under test
Note 1 to entry: Attenuation (L) is determined as the ratio of the input power (P ) to output power (P ) of the
in out
cabling under test, given as
× (P /P )
L= 10 × log
10 in out
Alternatively attenuation may be expressed as L= –10 × log × (P /P ). Both equations are mathematically
10 out in
equivalent, resulting in positive decibel values.
Note 2 to entry: Loss and attenuation are equivalent.
3.1.3
bidirectional measurement
two measurements of the same optical fibre made by launching light into opposite ends of that
fibre
3.1.4
configuration
form or arrangement of parts or elements such as terminations, connections and splices
3.1.5
connector
component normally attached to an optical cable or piece of apparatus, for the purpose of
providing frequent optical interconnection/disconnection of optical fibres or cables
[SOURCE: IEC TR 61931:1998, 2.6.1]
3.1.6
light source power meter
LSPM
test system consisting of a light source (LS), power meter (PM) and associated test cords
used to measure the attenuation of installed cable plant
3.1.7
optical return loss
ORL
ratio of the input power (P ) of the cabling under test to the backward power (P ), reflected
in r
...