SIST EN IEC 61281-1:2018

Fibre optic communication subsystems - Part 1: Generic specification (IEC 61281-1:2017)

This part of IEC 61281 is a generic specification for fibre optic communication subsystems
(FOCSs).
The parameters defined herein form a specifiable minimum set of specifications that are
common to all fibre optic subsystems. Additional parameters can be used depending on
the particular application and technology. Those additional parameters will be specified in the
relevant documents, as appropriate.
Each specified parameter is measured using one of the test procedures. The use of these
parameters for system design is given in design guides.

Lichtwellenleiter-Kommunikationsuntersysteme - Teil 1: Fachgrundspezifikation (IEC 61281-1:2017)

Sous-systèmes de télécommunications par fibres optiques - Partie 1: Spécification générique (IEC 61281-1:2017)

IEC 61281-1:2017 est une spécification générique relative aux sous-systèmes de télécommunications fibroniques (FOCS, fibre optic communication subsystem). Les paramètres définis dans le présent document constituent un ensemble minimal de spécifications, communes à tous les sous-systèmes fibroniques. Des paramètres supplémentaires peuvent être utilisés, selon les spécificités de l'application et des technologies. Ces paramètres supplémentaires seront spécifiés dans les documents appropriés, suivant le cas. Chaque paramètre spécifié est mesuré au moyen de l'un des modes opératoires d'essai. L'utilisation de ces paramètres pour la conception de systèmes est décrite dans les guides de conception. Cette deuxième édition annule et remplace la première édition parue en 1999. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: ajout de nouvelles définitions.
Mots clés : sous-systèmes de télécommunications fibroniques (FOCS, fibre optic communication subsystem)

Optični komunikacijski podsistemi - 1. del: Splošna specifikacija (IEC 61281-1:2017)

Ta del standarda IEC 61281 je splošna specifikacija za komunikacijske podsisteme optičnih vlaken (FOCS).
Tu določeni parametri predstavljajo določen minimalni sklop specifikacij, ki so skupne vsem podsistemom optičnih vlaken. Glede na posamezno uporabo in tehnologijo lahko uporabite dodatne parametre. Ti dodatni parametri bodo ustrezno določeni v zadevnih dokumentih.
Vsak od določenih parametrov bo izmerjen s pomočjo enega od preskusnih postopkov. Uporaba teh parametrov za oblikovanje sistema je podana v smernicah za oblikovanje.

General Information

• Status: Published
• Publication Date: 26-Mar-2018
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: MOC - Mobile Communications
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 14-Mar-2018
• Due Date: 19-May-2018
• Completion Date: 27-Mar-2018
• Ref Project: EN IEC 61281-1:2018 - Fibre optic communication subsystems - Part 1: Generic specification

Relations

• Revised: SIST EN 61281-1:2001 - Fibre optic communication subsystems -- Part 1: Generic specification
• Effective Date: 02-Aug-2016
• Replaces: SIST EN 61281-1:2001 - Fibre optic communication subsystems -- Part 1: Generic specification
• Effective Date: 13-Mar-2018

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 61281-1:2018
01-maj-2018
1DGRPHãþD
SIST EN 61281-1:2001
2SWLþQLNRPXQLNDFLMVNLSRGVLVWHPLGHO6SORãQDVSHFLILNDFLMD,(&

Fibre optic communication subsystems - Part 1: Generic specification (IEC 61281-
1:2017)
Lichtwellenleiter-Kommunikationsuntersysteme - Teil 1: Fachgrundspezifikation (IEC
61281-1:2017)
Sous-systèmes de télécommunications par fibres optiques - Partie 1: Spécification
générique (IEC 61281-1:2017)
Ta slovenski standard je istoveten z: EN IEC 61281-1:2018
ICS:
33.180.01 6LVWHPL]RSWLþQLPLYODNQLQD Fibre optic systems in
VSORãQR general
SIST EN IEC 61281-1:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 61281-1:2018

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SIST EN IEC 61281-1:2018


EUROPEAN STANDARD EN IEC 61281-1

NORME EUROPÉENNE

EUROPÄISCHE NORM
March 2018
ICS 33.180.01 Supersedes EN 61281-1:1999
English Version
Fibre optic communication subsystems - Part 1: Generic
specification
(IEC 61281-1:2017)
Sous-systèmes de télécommunications fibroniques - Partie Lichtwellenleiter-Kommunikationsuntersysteme - Teil 1:
1: Spécification générique Fachgrundspezifikation
(IEC 61281-1:2017) (IEC 61281-1:2017)
This European Standard was approved by CENELEC on 2018-01-19. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 61281-1:2018 E

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SIST EN IEC 61281-1:2018
EN IEC 61281-1:2018 (E)

European foreword
The text of document 86C/1408/CDV, future edition 2 of IEC 61281-1, prepared by IEC/SC 86C "Fibre
optic systems and active devices, of IEC technical committee 86: Fibre optics" was submitted to the
IEC-CENELEC parallel vote and approved by CENELEC as EN IEC 61281-1:2018.

The following dates are fixed:
(dop) 2018-10-19
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2021-01-19
standards conflicting with the
document have to be withdrawn

This document supersedes EN 61281-1:1999.

This edition constitutes a technical revision. With respect to the previous edition, several new
definitions are added.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 61281-1:2017 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 61280-1-1 NOTE Harmonized as EN 61280-1-1.
IEC 61280-1-3 NOTE Harmonized as EN 61280-1-3.
IEC 61280-1-4 NOTE Harmonized as EN 61280-1-4.
IEC 61280-2-1 NOTE Harmonized as EN 61280-2-1.
IEC 61280-2-2 NOTE Harmonized as EN 61280-2-2.
IEC 61280-2-3 NOTE Harmonized as EN 61280-2-3.
IEC 61280-2-8 NOTE Harmonized as EN 61280-2-8.
IEC 61280-2-9 NOTE Harmonized as EN 61280-2-9.
IEC 61280-2-10 NOTE Harmonized as EN 61280-2-10.
IEC 61280-2-11 NOTE Harmonized as EN 61280-2-11.
IEC 61280-2-12 NOTE Harmonized as EN 61280-2-12.
IEC 61280-4-1 NOTE Harmonized as EN 61280-4-1.
IEC 61280-4-2 NOTE Harmonized as EN 61280-4-2.
IEC 61280-4-4 NOTE Harmonized as EN 61280-4-4.
IEC 62614 NOTE Harmonized as EN 62614.
IEC 61290-1-1 NOTE Harmonized as EN 61290-1-1.
IEC 61290-1-2 NOTE Harmonized as EN 61290-1-2.
IEC 61290-1-3 NOTE Harmonized as EN 61290-1-3.
IEC 61290-3-1 NOTE Harmonized as EN 61290-3-1.
2

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SIST EN IEC 61281-1:2018
EN IEC 61281-1:2018 (E)

IEC 61290-3-2 NOTE Harmonized as EN 61290-3-2.
IEC 61290-3-3 NOTE Harmonized as EN 61290-3-3.
IEC 61290-4-1 NOTE Harmonized as EN 61290-4-1.
IEC 61290-4-2 NOTE Harmonized as EN 61290-4-2.
IEC 61290-4-3 NOTE Harmonized as EN 61290-4-3.
IEC 61290-5-1 NOTE Harmonized as EN 61290-5-1.
IEC 61290-5-2 NOTE Harmonized as EN 61290-5-2.
IEC 61290-5-3 NOTE Harmonized as EN 61290-5-3.
IEC 61290-6-1 NOTE Harmonized as EN 61290-6-1.
IEC 61290-7-1 NOTE Harmonized as EN 61290-7-1.
IEC 61290-10-1 NOTE Harmonized as EN 61290-10-1.
IEC 61290-10-2 NOTE Harmonized as EN 61290-10-2.
IEC 61290-10-3 NOTE Harmonized as EN 61290-10-3.
IEC 61290-10-4 NOTE Harmonized as EN 61290-10-4.
IEC 61290-10-5 NOTE Harmonized as EN 61290-10-5.
IEC 61290-11-1 NOTE Harmonized as EN 61290-11-1.
IEC 61290-11-2 NOTE Harmonized as EN 61290-11-2.
IEC 60793-1-41 NOTE Harmonized as EN 60793-1-41.
IEC 60793-2 NOTE Harmonized as EN 60793-2.
IEC 60793-2-10 NOTE Harmonized as EN 60793-2-10.
IEC 60793-2-50 NOTE Harmonized as EN 60793-2-50.
IEC 60794-1-1 NOTE Harmonized as EN 60794-1-1.
IEC 60869-1:2012 NOTE Harmonized as EN 60869-1:2013 (not modified).
IEC 60874-1:2011 NOTE Harmonized as EN 60874-1:2012 (not modified).
IEC 60875-1:2015 NOTE Harmonized as EN 60875-1:2015 (not modified).
IEC 60876-1:2014 NOTE Harmonized as EN 60876-1:2014 (not modified).
IEC 61073-1 NOTE Harmonized as EN 61073-1.
IEC 61274-1 NOTE Harmonized as EN 61274-1
IEC 61291 (series) NOTE Harmonized as EN 61291 (series).
IEC 61291-1:2012 NOTE Harmonized as EN 61291-1:2012 (not modified).
IEC 61291-2 NOTE Harmonized as EN 61291-2.
IEC 61291-4 NOTE Harmonized as EN 61291-4.
IEC 61703 NOTE Harmonized as EN 61703.
IEC 61753 (series) NOTE Harmonized in EN 61753 (series).
IEC 62149 (series) NOTE Harmonized in EN 62149 (series).
IEC 62149-1 NOTE Harmonized as EN 62149-1.
IEC 62343-1 (series) NOTE Harmonized as EN 62343-1 (series).
IEC 62343-3 (series) NOTE Harmonized as EN 62343-3 (series).



3

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SIST EN IEC 61281-1:2018



IEC 61281-1

®


Edition 2.0 2017-12




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Fibre optic communication subsystems –

Part 1: Generic specification




Sous-systèmes de télécommunications fibroniques –

Partie 1: Spécification générique















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 33.180.01 ISBN 978-2-8322-5188-1



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 61281-1:2018
– 2 – IEC 61281-1:2017 © IEC 2017

CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and acronyms . 22
4.1 Symbols . 22
4.2 Acronyms . 22
5 Subsystem characteristics . 23
5.1 General aspects . 23
5.2 Digital fibre optic subsystems . 26
5.2.1 General description . 26
5.2.2 Digital subsystem characteristics . 26
5.2.3 Digital transmitter characteristics . 26
5.2.4 Digital receiver characteristics . 27
5.2.5 Digital regenerator characteristics . 28
5.3 Analogue fibre optic subsystems . 29
5.3.1 General description . 29
5.3.2 Analogue subsystem characteristics . 29
5.3.3 Analogue transmitter characteristics . 30
5.3.4 Analogue receiver characteristics . 31
5.3.5 Analogue repeater characteristics . 31
5.4 Fibre optic links . 32
5.4.1 General description . 32
5.4.2 Fibre optic cable plant characteristics . 32
5.4.3 Fibre optic cable section characteristics . 33
5.4.4 Optical fibre splice and connector characteristics . 33
5.4.5 Optical device characteristics . 33
5.4.6 Optical amplifier characteristics . 34
Bibliography . 36

Figure 1 – Simplest basic fibre optic system . 24
Figure 2 –More complex BFOS . 24
Figure 3 – Interconnected BFOSs forming a fibre optic subsystem . 25
Figure 4 – BFOS with multiport terminal devices . 25

Table 1 – Digital subsystem characteristics . 26
Table 2 – Digital transmitter characteristics. 27
Table 3 – Digital receiver characteristics . 28
Table 4 – Digital regenerator characteristics . 29
Table 5 – Analogue subsystem characteristics . 30
Table 6 – Analogue transmitter characteristics . 30
Table 7 – Analogue receiver characteristics . 31
Table 8 – Analogue repeater characteristics . 32

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SIST EN IEC 61281-1:2018
IEC 61281-1:2017 © IEC 2017 – 3 –
Table 9 – Fibre optic cable plant characteristics . 33
Table 10 – Optical device characteristics . 33
Table 11 – Optical fibre amplifier characteristics . 34
Table 12 – Semiconductor optical amplifier characteristics . 35

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

FIBRE OPTIC COMMUNICATION SUBSYSTEMS –

Part 1: Generic specification

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 61281-1 has been prepared by subcommittee 86C: 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. This edition
constitutes a technical revision.
This edition includes the following significant technical change with respect to the previous
edition: addition of new definitions.
The text of this International Standard is based on the following documents:
CDV Report on voting
86C/1408/CDV 86C/1468/RVC

Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.

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SIST EN IEC 61281-1:2018
IEC 61281-1:2017 © IEC 2017 – 5 –
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61281-1 series, published under the general title Fibre optic
communication subsystems, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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FIBRE OPTIC COMMUNICATION SUBSYSTEMS –

Part 1: Generic specification



1 Scope
This part of IEC 61281 is a generic specification for fibre optic communication subsystems
(FOCSs).
The parameters defined herein form a specifiable minimum set of specifications that are
common to all fibre optic subsystems. Additional parameters can be used depending on
the particular application and technology. Those additional parameters will be specified in the
relevant documents, as appropriate.
Each specified parameter is measured using one of the test procedures. The use of these
parameters for system design is given in design guides.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
ISO and IEC maintain terminological 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
NOTE Within a definition, terms defined elsewhere in Clause 3 are in italics.
3.1
active optical device
optical device, other than an optical dynamic device, exhibiting one or more of the following
functions:
• generation or detection of optical power;
• conversion of an electronic signal to a corresponding optical one or vice versa;
• optical amplification or optical regeneration (2R or 3R) of an optical signal;
• direct conversion of the optical frequency of an optical signal
Note 1 to entry: Active optical devices may comprise passive optical elements.
[SOURCE: IEC TS 62538:2008, 2.1.2, modified – The term "optical active device" has been
replaced by "active optical device".]

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3.2
amplified spontaneous emission
ASE
optical power associated to spontaneously emitted photon amplified by an active medium in
an optical amplifier
Note 1 to entry: This note applies to the French language only.
[SOURCE: IEC TR 61931:1998, 2.7.87 – The note has been added.]
3.3
analogue input signal bandwidth
bandwidth at the electrical input to the transmitter
3.4
attenuation
reduction of optical power induced by transmission through a medium, given as L (dB) where
L = 10 log (P /P ), and P and P are the power into and out of the transmission medium
10 in out in out
Note 1 to entry: P and P are typically expressed in mW.
in out
3.5
bandwidth
difference (expressed in Hz) between the highest and lowest modulation frequencies at which
the modulus of the power spectrum or of the complex transfer function is one-half of the peak
value of the modulus
3.6
basic fibre optic system
BFOS
serial combination of a transmit terminal device, a fibre optic link, and a receive terminal
device
Note 1 to entry: This note applies to the French language only.
3.7
bit-error ratio
BER
number of errored bits divided by the total number of bits, over some stipulated period of time
Note 1 to entry: This note applies to the French language only.
3.8
branching device
BD
passive device whose purpose is to transfer optical power between two or more ports in a
predetermined manner
Note 1 to entry: The ports may be connected to waveguides, sources, detectors etc.
Note 2 to entry: This note applies to the French language only.
[SOURCE: IEC 60050-731:1991, 731-05-10, modified – The other terms "optical fibre coupler"
and "optical coupler" have been deleted, and the acronym "BD" has been added. Note 2 has
also been added.]

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3.9
carrier-to-noise ratio
CNR
ratio of carrier power to noise power in a channel of defined bandwidth, prior to any non-linear
processing
Note 1 to entry: Carrier-to-noise ratio is expressed in dB.
Note 2 to entry: This note applies to the French language only.
3.10
centre wavelength
mean of the closest spaced half-power wavelengths, one above and one below the peak
wavelength of an optical spectrum
Note 1 to entry: Other spectral wavelengths are centroidal wavelengths, half-power wavelengths, and peak
wavelengths.
3.11
centroidal wavelength
mean or average wavelength of an optical spectrum
Note 1 to entry: Other spectral wavelengths are centre wavelengths, half-power wavelengths, and peak
wavelengths.
3.12
chirping
change of the wavelength or optical frequency of an intensity-modulated transmitter as a
function of the instantaneous intensity of the modulating signal
Note 1 to entry: When chirped signals are transmitted through an optical fibre, the signal waveform is distorted by
chromatic dispersion. This process may cause a degradation in the quality of performance, designated as a
chirping penalty.
3.13
chromatic dispersion
dispersion
rate of change in group delay to wavelength between the end points of the fibre optic cable
plant
Note 1 to entry: Chromatic dispersion is usually expressed in ps/nm.
3.14
encircled flux
fraction of cumulative power to total output power as a function of radial distance from the
centre of the multimode optical fibre’s core
3.15
environmental condition
characteristic of the environment that may affect performance of a device or system
Note 1 to entry: Examples of ambient conditions are pressure, temperature, humidity, radiation, and vibration.
[SOURCE: IEC 60050-151:2001, 151-16-03, modified – The other term "ambient condition"
has been deleted.]
3.16
extinction ratio
ratio of the average power level of logical "1" to the average power level of logical "0", in a
digital transmission system
Note 1 to entry: Extinction ratio is expressed in dB.

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3.17
fibre optic cable plant
FOCP
serial combination of fibre optic cable sections, connectors, and splices providing the optical
path between two terminal devices, between two optical devices, or between a terminal
device and an optical device
Note 1 to entry: This note applies to the French language only.
3.18
fibre optic cable section
single optical fibre cable which can be unjointed
3.19
fibre optic communication system
assembly of fibre optic subsystems for transmitting information
3.20
fibre optic link
FOL
serial combination of a fibre optic cable plant and optical devices, providing the optical path
between a transmit terminal device and a receive terminal device
Note 1 to entry: This is equivalent to a basic fibre optic subsystem minus the transmitter and receiver.
Note 2 to entry: This note applies to the French language only.
3.21
fibre optic subsystem
assembly of interconnected basic fibre optic subsystems
Note to entry: The assembly is specified at defined interfaces within the fibre optic system.
3.22
fibre optic terminal device
device that converts one or more electrical signals into one or more optical signals, or vice-
versa, and that is connected to at least one optical fibre
Note 1 to entry: A fibre optic terminal device always has one or more integral connectors or pigtails.
Note 2 to entry: Examples include a receive terminal device, a transmit terminal device, a transmitter, and a
receiver.
3.23
full-width at half-maximum
FWHM
positive difference of the closest spaced half-power wavelengths, one above and one below
the peak wavelength of an optical spectrum
Note 1 to entry: Other spectral widths are N-dB-down widths and root-mean-square widths.
Note 2 to entry: The FWHM equals the N-dB-down width where N = 3.
Note 3 to entry: This note applies to the French language only.
3.24
half-power wavelength
wavelength corresponding to a half peak power value of the optical spectrum
Note 1 to entry: Other spectral wavelengths are central wavelengths, centroidal wavelengths, and peak
wavelengths.

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3.25
harmonic distortion
distortion in a system or transducer characterized by the presence at the output of spectral
components which are harmonically related to the spectral components of the input signal
Note 1 to entry: See IEEE Dictionary Online.
3.26
input power range
range of optical power levels such that, for any input signal power of the OFA which lies within
this range, the corresponding output signal power lies in the specified output power range,
where the OFA performance is ensured
[SOURCE: IEC 61291-1:2012, 3.2.1.36, modified – In the definition, the two occurrences of
the term "OA" have been replaced by "OFA".]
3.27
intermodulation distortion
IMD
distortion characterized by the appearance of spectral components with frequencies equal to
the sums and differences of integral multiples of two or more component frequencies of the
input signal
Note 1 to entry: See IEEE Dictionary Online.
Note 2 to entry: This note applies to the French language only.
3.28
intersymbol interference
ISI
overlap of adjacent pulses as caused by the limited bandwidth characteristics of the optical
devices in a fibre optic link
Note 1 to entry: This note applies to the French language only.
3.29
jitter
random or data-induced short-term non-cumulative variations of the phases or of the
significant instants of a digital signal from their ideal positions in time relative to a reference
(clock) signal
Note 1 to entry: In practice, "short-term" embraces all spectral components of 10 Hz and above.
Note 2 to entry: Jitter is expressed in terms of absolute time or as a fraction of a unit interval.
3.30
jitter tolerance
maximum jitter amplitude that a digital receiver can accept for a given penalty or alternatively
without the addition of a given number of errors to the digital signal
Note 1 to entry: The maximum jitter amplitude tolerated is generally dependent on the frequency of the jitter.
3.31
jitter transfer function
ratio of the output jitter to the applied input jitter as a function of modulation frequency
3.32
light source
device or instrument that emits light that is coupled into a fibre under test

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SIST EN IEC 61281-1:2018
IEC 61281-1:2017 © IEC 2017 – 11 –
3.33
line code
sequence of symbols that the binary data is converted into for purposes of transmission
Note 1 to entry: Examples include Manchester, return-to-zero, block codes, digital scrambling.
Note 2 to entry: Line codes are used to recover timing, and in some cases they may be used to detect line errors,
and to convey additional information.
3.34
loss budget
sum of the fibre optic link loss and the power penalty
Note 1 to entry: The loss budget equals the power budget minus the working margin.
Note 2 to entry: The initial/final l
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