IEC 61280-2-1:2010

Fibre optic communication subsystem test procedures - Part 2-1: Digital systems - Receiver sensitivity and overload measurement

IEC 61280-2-1:2010 describes the test procedures applicable to digital fibre optic communication and data systems. The object of this test procedure is to measure the minimum and maximum optical powers required and allowed at the optical input port of a fibre optic system to ensure its operation within specified limits. Another objective is to verify that the guaranteed error performance is obtained at the minimum and the maximum optical input powers specified by the terminal equipment manufacturer. This second edition cancels and replaces the first edition, published in 1998, and constitutes a technical revision. The main changes with respect to the previous edition are:
- revised to include the requirements associated with data communication equipment, regenerators and amplifiers;
- the term "jumper lead" has been replaced by "test cord";
- a section for definitions has been added;
- a section on measurement uncertainties has been added. This bilingual version (2015-12) corresponds to the monolingual English version, published in 2010-03. Keywords: digital fibre optic communication and data systems, optical input port

Procédures d'essai des sous-systèmes de télécommunications à fibres optiques - Partie 2-1: Systèmes numériques - Mesure de la sensibilité et de la surcharge d'un récepteur

L'IEC 61280-2-1:2010 décrit les procédures d'essai applicables aux systèmes de télécommunications et de données à fibres optiques numériques. L'objet de cette procédure d'essai est la mesure des puissances optiques minimale et maximale requises et admissibles au port d'entrée optique d'un système à fibres optiques, pour assurer son fonctionnement dans les limites spécifiées. Un autre objet est la vérification du critère d'erreur garanti aux puissances d'entrée minimale et maximale spécifiées par le fabricant de l'équipement terminal. Cette seconde édition annule et remplace la première édition parue en 1998 et constitue une révision technique. Les principales modifications par rapport à l'édition antérieure sont indiquées ci-dessous:
- révision en vue d'inclure les exigences associées aux matériels de communications de données, régénérateurs et amplificateurs;
- the terme "câble de liaison" a été remplacé par "cordon d'essai";
- une section relative aux définitions a été ajoutée;
- une section traitant des incertitudes de mesure a été ajoutée. La présente version bilingue (2015-12) correspon à la version anglaise monolingue publiée en 2010-03. Mots clés: systèmes de télécommunications et de données à fibres optiques numériques, port d'entrée optique

General Information

• Status: Published
• Publication Date: 17-Mar-2010
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: SC 86C - Fibre optic systems, sensing and active devices
• Drafting Committee: WG 1 - TC 86/SC 86C/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 18-Mar-2010
• Completion Date: 30-Jun-2010

Relations

• Revises: IEC 61280-2-1:1998 - Fibre optic communication subsystem basic test procedures - Part 2-1: Test procedures for digital systems - Receiver sensitivity and overload measurement
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61280-2-1 ®
Edition 2.0 2010-03
INTERNATIONAL
STANDARD
Fibre optic communication subsystem test procedures –
Part 2-1: Digital systems – Receiver sensitivity and overload measurement

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
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IEC 61280-2-1 ®
Edition 2.0 2010-03
INTERNATIONAL
STANDARD
Fibre optic communication subsystem test procedures –
Part 2-1: Digital systems – Receiver sensitivity and overload measurement

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
N
ICS 33.180.01 ISBN 978-2-88910-474-1
– 2 – 61280-2-1 © IEC:2010(E)
CONTENTS
FOREWORD.3
1 Scope and object.5
2 Terms and definitions .5
3 Apparatus.6
3.1 General .6
3.2 BER test set .6
3.2.1 Data generator .7
3.2.2 Error counter .7
3.3 Optical power meter .7
3.4 Variable optical attenuator.7
3.5 Optical splitter .7
3.6 Test cords .7
3.7 Optical transmit interface.7
4 Equipment under test (EUT) .8
5 Test procedure .8
5.1 Operating conditions and test environment.8
5.2 Connector end-face cleaning.8
5.3 Measurement of input sensitivity .8
5.3.1 Optical input power calibration.10
5.3.2 BER or EBR determination.10
5.4 Measurement of overload level.11
5.4.1 Power level calibration.11
5.4.2 Overload level determination .12
5.4.3 Calculation of overload level.12
6 Measurement uncertainties.13
7 Test results .13
7.1 Required information .13
7.2 Available information.13
Bibliography.14

Figure 1 – Optical fibre system .5
Figure 2 – Setup for the measurement of input sensitivity of a receive terminal.9
Figure 3 – Setup for the measurement of input sensitivity of an amplifier or regenerator .9
Figure 4 – Setup for the measurement of overload level for a receive terminal.11
Figure 5 – Setup for the measurement of overload level for an amplifier or regenerator .12

Table 1 – Minimum monitoring time.10

61280-2-1 © IEC:2010(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 2-1: Digital systems –
Receiver sensitivity and overload measurement

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 61280-2-1 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 1998, and constitutes
a technical revision.
The main changes with respect to the previous edition are listed below:
– revised to include the requirements associated with data communication equipment,
regenerators and amplifiers;
– the term “jumper lead” has been replaced by “test cord”:
– a section for definitions has been added;
– a section on measurement uncertainties has been added.

– 4 – 61280-2-1 © IEC:2010(E)
The text of this standard is based on the following documents:
CDV Report on voting
86C/881/CDV 86C/945/RVC
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 of 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.
A bilingual version of this publication may be issued at a later date.

61280-2-1 © IEC:2010(E) – 5 –
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 2-1: Digital systems –
Receiver sensitivity and overload measurement

1 Scope and object
This part of IEC 61280 describes the test procedures applicable to digital fibre optic
communication and data systems.
The object of this test procedure is to measure the minimum and maximum optical powers
required and allowed at the optical input port of a fibre optic system to ensure its operation
within specified limits. Another objective is to verify that the guaranteed error performance is
obtained at the minimum and the maximum optical input powers specified by the terminal
equipment manufacturer.
Figure 1 shows the typical elements associated with optical fibre systems. Optical amplifiers
or regenerators may be used in long haul telecom systems, but are not usually associated
with data transport systems such as Ethernet, etc. In bi-directional systems the transmitter
and corresponding receiver are usually co-located, as indicated by the dotted lines. This
specification is concerned with the characteristics of the optical input interface of the receiver,
amplifier or regenerator shown.
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OpOpOpOpticticticticaaaallll
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TrTrTrTransansansansmmmmiiiitttt
InInInInInInteteteteteterrrrrrfafafafafafacccccceeeeee ReReReReggggeeeennnn.
SSSSSystystystystysteeeeemmmmm InInInInteteteterrrrfafafafacccceeee
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OpOpOpOpticticticticaaaallll OpOpOpticticticaaalll OpOpOpOpOpticticticticticaaaaalllll
TrTrTrTransansansansmmmmiiiitttt AmAmAmpppllliiifffiiieeerrr///
ReReReReReccccceeeeeiiiiivvvvveeeee
InInInInteteteterrrrfafafafacccceeee ReReRegggeeennn. InInInInInteteteteterrrrrfafafafafaccccceeeee
SSSSystystystysteeeemmmm SSSSystystystysteeeemmmm
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TTTTrrrransansansansmmmmitititit RecRecRecReceiveiveiveiveeee
EEEEquiquiquiquippppmmmmeeeentntntnt EEEEquiquiquiquippppmmmmeeeentntntnt
MMeeasurasureemmeenntt P Pooiinntt MMeeasurasureemmeenntt P Pooiinntt

IEC  469/10
Figure 1 – Optical fibre system
It should be noted that the performance of fibre optic receivers may differ for different signal
formats. It is therefore necessary to use the signal format that represents actual operating
conditions.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

– 6 – 61280-2-1 © IEC:2010(E)
2.1
bit error ratio (BER)
the number of errored bits divided by the total number of bits, over some stipulated period of
time
[IEC 61931, definition 2.9.33]
2.2
bit sequence
a defined sequence of ones (1) and zeros (0) in a digital signal
2.3
bit pattern
a predetermined sequence of 1’s and 0’s in a digital signal which is repeated at regular
intervals
2.4
errored block ratio (EBR)
the number of errored blocks, containing a defined number of digits, divided by the total
number of blocks received in a specified period of time. An errored block may contain more
than one errored bit
2.5
overload level
the maximum input power above which a specified quality of performance is no longer
achieved
2.6
pseudo random binary sequence (PRBS)
a repeated bit sequence which simulates a random pattern of 1’s and 0’s. It is generated by
th
the addition of the r preceding digit of a sequence of n bi
...

IEC 61280-2-1 ®
Edition 2.0 2010-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic communication subsystem test procedures –
Part 2-1: Digital systems – Receiver sensitivity and overload measurement

Procédures d'essai des sous-systèmes de télécommunications à fibres
optiques –
Partie 2-1: Systèmes numériques – Mesure de la sensibilité et de la surcharge
d'un récepteur
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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International Standards for all electrical, electronic and related technologies.

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IEC 61280-2-1 ®
Edition 2.0 2010-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic communication subsystem test procedures –

Part 2-1: Digital systems – Receiver sensitivity and overload measurement

Procédures d'essai des sous-systèmes de télécommunications à fibres

optiques –
Partie 2-1: Systèmes numériques – Mesure de la sensibilité et de la surcharge

d'un récepteur
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-3072-5

– 2 – IEC 61280-2-1:2010  IEC 2010
CONTENTS
FOREWORD . 3
1 Scope and object . 5
2 Terms and definitions . 5
3 Apparatus . 6
3.1 General . 6
3.2 BER test set . 6
3.2.1 Data generator . 7
3.2.2 Error counter . 7
3.3 Optical power meter . 7
3.4 Variable optical attenuator . 7
3.5 Optical splitter . 7
3.6 Test cords . 7
3.7 Optical transmit interface . 7
4 Equipment under test (EUT) . 8
5 Test procedure . 8
5.1 Operating conditions and test environment . 8
5.2 Connector end-face cleaning . 8
5.3 Measurement of input sensitivity . 8
5.3.1 Optical input power calibration . 10
5.3.2 BER or EBR determination . 10
5.4 Measurement of overload level . 11
5.4.1 General . 11
5.4.2 Power level calibration. 11
5.4.3 Overload level determination . 12
5.4.4 Calculation of overload level . 12
6 Measurement uncertainties . 13
7 Test results . 13
7.1 Required information . 13
7.2 Available information . 13
Bibliography . 14

Figure 1 – Optical fibre system . 5
Figure 2 – Setup for the measurement of input sensitivity of a receive terminal . 9
Figure 3 – Setup for the measurement of input sensitivity of an amplifier or regenerator . 9
Figure 4 – Setup for the measurement of overload level for a receive terminal . 11
Figure 5 – Setup for the measurement of overload level for an amplifier or regenerator . 12

Table 1 – Minimum monitoring time. 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 2-1: Digital systems –
Receiver sensitivity and overload measurement

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 61280-2-1 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 1998, and constitutes
a technical revision.
The main changes with respect to the previous edition are listed below:
– revised to include the requirements associated with data communication equipment,
regenerators and amplifiers;
– the term “jumper lead” has been replaced by “test cord”:
– a section for definitions has been added;
– a section on measurement uncertainties has been added.

– 4 – IEC 61280-2-1:2010  IEC 2010
This bilingual version (2015-12) corresponds to the monolingual English version, published in
2010-03.
The text of this standard is based on the following documents:
CDV Report on voting
86C/881/CDV 86C/945/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of 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.
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 2-1: Digital systems –
Receiver sensitivity and overload measurement

1 Scope and object
This part of IEC 61280 describes the test procedures applicable to digital fibre optic
communication and data systems.
The object of this test procedure is to measure the minimum and maximum optical powers
required and allowed at the optical input port of a fibre optic system to ensure its operation
within specified limits. Another objective is to verify that the guaranteed error performance is
obtained at the minimum and the maximum optical input powers specified by the terminal
equipment manufacturer.
Figure 1 shows the typical elements associated with optical fibre systems. Optical amplifiers
or regenerators may be used in long haul telecom systems, but are not usually associated
with data transport systems such as Ethernet, etc. In bi-directional systems the transmitter
and corresponding receiver are usually co-located, as indicated by the dotted lines. This
specification is concerned with the characteristics of the optical input interface of the receiver,
amplifier or regenerator shown.
OOOOOOppppppttttttiiiiiiccccccaaaaaallllll OOOOptptptptiiiiccccaaaallll  FFFFiiiibbbbrrrre e e e LiLiLiLinnnnkkkk OOOOppppttttiiiiccccaaaallll OOOOptptptptiiiiccccaaaallll  FFFFiiiibbbbrrrre e e e LiLiLiLinnnnkkkk
OOOOppppttttiiiiccccaaaallll
RRRRRRececececececeieieieieieivvvvvveeeeee AAAAmmmmplplplpliiiiffffiiiierererer////
TTTTrrrransansansansmmmmiiiitttt
IIIIIInnnnnntttttteeeeeerrrrrrffffffaaaaaacccccceeeeee RRRRegegegegenenenen.
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IEC  469/10
Figure 1 – Optical fibre system
It should be noted that the performance of fibre optic receivers may differ for different signal
formats. It is therefore necessary to use the signal format that represents actual operating
conditions.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

– 6 – IEC 61280-2-1:2010  IEC 2010
2.1
bit error ratio (BER)
the number of errored bits divided by the total number of bits, over some stipulated period of
time
[IEC 61931, definition 2.9.33]
2.2
bit sequence
a defined sequence of ones (1) and zeros (0) in a digital signal
2.3
bit pattern
a predetermined sequence of 1’s and 0’s in a digital signal which is repeated at regular
intervals
2.4
errored block ratio (EBR)
the number of errored blocks, containing a defined number of digits, divided by the total
number of blocks received in a specified period of time. An errored block may contain more
than one errored bit
2.5
overload level
the maximum input power above which a specified quality of performance is no longer
achieved
2.6
pseudo random binary sequence (PRBS)
a repeated bit sequence which simulates a random pattern of 1’s and 0’s. It is generated by
th
the addition of the r preceding digit of a sequence of n bits and eliminating the sequence of n
n
0’s (or n 1’s). The pattern repeats after 2 -1 bits
2.7
receiver sensitivity
the minimum power required to achieve a specified quality of performance
[IEC 61931, definition 2.7.58, modified ]
2.8
system input and output signals
for the purpose of this specification, the system input and output are defined as signals which
interface with external equipment. These signals have specified formats specific to the
application and may be electrical or optical. The signals are accessed via physical interfaces
that are specific to the equipment
3 Apparatus
3.1 General
The test setup is shown in Figure 2. It is important that test cords 3 and 4 are of a similar type
and make and are of equal length.
3.2 BER test set
The BER test set is made up of the elements described here.

3.2.1 Data generator
The data generator of the BER test set shall be capable of providing a data input to the
system which may be a pseudo-random sequence or otherwise specified bit pattern with the
signal format (pulse shape, amplitude, etc.) that is consistent with the requirements at the
system input interface of the EUT.
As a minimum requirement the data generator shall be capable of providing the following
output date formats; other data formats may be used in compliance with the system
requirements.
• a 2 -1 pseudo-random data stream;
• an all 1 data stream;
• a 1 + 15 zeros data stream.
The format (pulse shape, amplitude, etc.) of the test signal shall be compliant with that
required at the transmit input interface. The receiver portion of the test equipment shall be
able to interface with the system output for the measurement of digital errors.
3.2.2 Error counter
The error counter of the BER test set shall be able to interface with the output of the EUT. It
shall be capable counting single errors or errored blocks at the data rate of system output
interface of the EUT. If the error counter has the facility for computing the BER or EBR value
–12
it must be capable of calculating a value as low as 10 .
3.3 Optical power meter
The optical power meter used shall have a resolution of at least 0,1 dB, shall be data format
and bit rate independent and shall have been calibrated for the wavelength and power range
of operation for the equipment to be tested. All measurements shall be recorded on the dB
scale.
3.4 Variable optical attenuator
The optical attenuator shall be capable of attenuation in steps less than or equal to 0,25 dB
and should be able to provide a total attenuation that is at least 5 dB greater than the
specified input range of the receiver under test. Care should be taken to avoid back reflection
into the transmitter.
3.5 Optical splitter
The optical splitter (coupler) shall have one input port and two output ports equipped with
appropriate connectors. The splitting ratio for the output ports should be 50 % ± 0,1 dB
(unless otherwise specified).
3.6 Test cords
Single-mode or multimode fibre reference test cords and fitted with the appropriate
connectors as required by the application shall be used, unless otherwise agreed. The optical
loss of the test cords including connectors shall not exceed 1,0 dB.
3.7 Optical transmit interface
The optical transmit interface shall have electrical and optical characteristics similar to those
of transmitters that are used in the specified fibre optic terminal devices, except that the
output power shall exceed the maximum specified input power of the receiver by at least
2 dB.
– 8 – IEC 61280-2-1:2010  IEC 2010
4 Equipment under test (EUT)
The EUT shall be a fibre optic receiver, optical amplifier or optical regenerator, including all
associated signal conditioning, processing and multiplexing equipment used in the system
under normal operating conditions. The system input and output terminations shall be those
normally seen by the user of the system.
5 Test procedure
The test procedure consists of the following steps.
5.1 Operating conditions and test environment
Unless otherwise specified, normal operating conditions apply. The ambient or reference point
temperature and humidity shall be specified.
Switch on the EUT and all test equipment (apply any special operating conditions to the EUT
if required) and allow 30 min. (unless otherwise specified) for the equipment to reach a
steady-state temperature and performance condition.
5.2 Connector end-face cleaning
Whenever optical connections are changed, the end faces of the connectors shall be cleaned.
Cleaning equipment (including apparatus, materials, and substances) and the methods to be
used shall be suitable for the connectors to be cleaned. Connector suppliers’ instructions
shall be consulted where doubt exists as to the suitability of particular equipment and
cleaning methods.
5.3 Measurement of input sensitivity
Connect the equipment as shown in Figure 2, if terminal equipment is tested, or Figure 3, if an
amplifier or regenerator is tested, and set the data generator and error counter to operate with
a pseudo random sequence with word length of 2 -1 (unless otherwise specified).

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IEC  470/10
Figure 2 – Setup for the measurement of input sensitivity of a receive terminal

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IEC  471/10
Figure 3 – Setup for the measurement of input sensitivity of an amplifier or regenerator

– 10 – IEC 61280-2-1:2010  IEC 2010
5.3.1 Optical input power calibration
This procedure shall be carried out as follows:
a) Disconnect the optical power meter from the output of optical test cord 4 and disconnect
the output of optical test cord 3 from the EUT.
b) Connect the optical power meter to the output of optical test cord 3.
c) Set the attenuator to 0 dB and measure the optical power.
d) Connect the optical power meter to the output of test cord 4 and re-connect the output of
optical test cord 3 to the EUT.
e) Measure the optical power.
f) Record any difference between the two measurements.
5.3.2 BER or EBR determination
The procedure consists of the following steps:
a) Adjust the optical attenuator to provide an optical power level which is 3 dB higher than
the minimum specified input power.
b) Adjust the optical attenuator to increase the attenuation until the first errors are observed.
If the error counter has the facility to compute the BER or EBR directly, record the result
and power level.
c) If such a facility is not provided, count the number of errors occurring in a defined
monitoring time that exceeds or is equal to the minimum monitoring time given in Table 1.
Calculate the error ratio using the following formula:
N BN
BER=  or  EBR=
DT DT
where
N is the number of errors observed in monitoring time;
D is the data rate;
T is the monitoring time;
B is the number of data in a block.
Table 1 – Minimum monitoring time
Data rate Minimum monitoring time, s
1 Mb/s < data rate < 30 Mb/s (1/data rate) × 10
Data rate > 30 Mb/s (1/data rate) × 10
NOTE When the EBR is measured, the minimum monitoring time should be multiplied by the number of data
bits in the block.
d) Record the calculated error ratio together with the optical power.
e) Increase the attenuation in steps of 1 dB and record the power level and the measured or
calculated error ratio for each step until the maximum error ratio specified for the
equipment is reached. As the specified maximum error ratio is approached, it may be
necessary increase the attenuation in smaller increments.
f) The input power level observed represents the receiver sensitivity or minimum required
input power level for the equipment to meet the error performance specified for that
equipment. Any difference between the actual and observed optical power determined by
the calibration procedure shall be taken into account.
g) It should be noted that some equipment has internal error monitoring and may output a
special signal at the system output to indicate loss of input when a specified error ratio is
reached. In such case, the input sensitivity shall be taken as the input level measured at
the onset of the special signal.

5.4 Measurement of overload level
5.4.1 General
Connect the equipment as shown in Figure 4 or Figure 5 and set the data generator and error
counter to operate with pseudo random sequence with word length of 2 -1 (unless otherwise
specified). For this test, the optical transmitter shall be capable of providing optical signal
power at the receive interface of the EUT to exceeds its maximum specified input power by at
least 0,5 dB.
5.4.2 Power level calibration
The procedure consists of the following steps:
a) Disconnect the output of optical test cord 2 from the EUT and connect it to the optical
power meter.
b) Adjust the optical attenuator to give an output power level which is 3 dB below the
maximum input power level specified by the manufacturer or supplier of the equipment. If
no such specification is available, set the input power level to a value equal to the
sensitivity power level. Any difference between the actual and observed optical power
determined by the calibration procedure shall be taken into account.
c) Note and record the output level and attenuator setting.
d) Disconnect the output of optical test cord 2 from the optical power meter and re-connect it
to the EUT.
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IEC  472/10
Figure 4 – Setup for the measurement of overload level for a receive terminal

– 12 – IEC 61280-2-1:2010  IEC 2010
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IEC  473/10
Figure 5 – Setup for the measurement of overload level for an amplifier or regenerator
5.4.3 Overload level determination
a) Adjust the optical attenuator to decrease the attenuation until the first few errors are
observed. If the error counter has the facility to compute the error ratio directly, record the
result and the value of the attenuator setting.
b) If such a facility is not provided, calculate the error ratio using the procedure described in
5.3.2.
c) Decrease further the value of the attenuator setting in small steps and measure or
calculate the error ratio until the maximum error ratio specified for the EUT has been
reached. Note and record the attenuator setting which indicates the overload point.
d) The transition from no errors or a very low error ratio to a very high error ratio may occur
between a very small change in input power which may be less than minimum increment
of the attenuator setting.
e) It should be noted that some equipments are equipped with internal error monitoring and
may output a special signal at the system output when a specified error ratio is reached.
In such a case, the overload level shall be taken as the input level measured at the onset
of the special signal.
5.4.4 Calculation of overload level
The overload level is calculated by adding the numerical value of the total decrease in
attenuation from the value set during the calibration procedure to the value of the optical
power measured in that procedure.
P = A – A + P  (expressed in dB)

max 0 1 0
where
P is the overload level, expressed in dB;
max
A is the attenuator setting during calibration, expressed in dB;
A is the attenuator setting at calibration, expressed in dB;
P is the power level at calibration, expressed in dB.
6 Measurement uncertainties
The following uncertainties in the measurement of sensitivity and overload level, excluding
operator error, have to be taken into account:
a) Calibration of the attenuator (for overload measurement only).
b) Calibration of the optical power meter.
c) Difference in the connector loss of the EUT and the optical power meter. This uncertainty
can be minimized by the use of test cords fitted with reference grade connectors.
7 Test results
The test results contain required and available information.
7.1 Required information
The required information shall be as follows:
a) The EUT identification.
b) Date and title of the test.
c) Operating conditions.
d) Identification of test methods.
e) Environmental conditions.
f) Procedures used.
g) Test results.
7.2 Available information
The available information shall be as follows:
a) Identification of the test equipment used.
b) Identification of test cords and connector parameters.
c) The optical power measurement uncertainty.
d) Names of test personnel.
e) Supply voltage(s) and current(s).
f) Data rate and input signal characteristics.
g) Input/output measurement conditions: wavelength, specified receiver sensitivity, maximum
receiver input.
h) Recommended warm-up time (time required for temperature stabilization).
i) Calibration details of optical power meter and optical attenuator.

– 14 – IEC 61280-2-1:2010  IEC 2010
Bibliography
EIA/TIA-526-3:1989, Fibre optic terminal equipment receiver sensitivity and maximum
receiver input
IEC 61931:1998, Fibre optic – Terminology

___________
– 16 – IEC 61280-2-1:2010  IEC 2010
SOMMAIRE
AVANT PROPOS . 17
1 Domaine d’application et objet . 19
2 Termes et définitions . 20
3 Appareillage . 21
3.1 Généralités . 21
3.2 Installation d'essai BER . 21
3.2.1 Générateur de données . 21
3.2.2 Compteur d’erreurs . 22
3.3 Appareil de mesure de la puissance optique . 22
3.4 Affaiblisseur optique variable . 22
3.5 Répartiteur optique . 22
3.6 Cordons d’essai . 22
3.7 Interface optique d’émission . 22
4 Matériel en essai (EUT, Equipment Under Test) . 22
5 Procédure d’essai: . 23
5.1 Conditions de fonctionnement et environnement d’essai . 23
5.2 Nettoyage de l’extrémité du connecteur . 23
5.3 Mesure de la sensibilité en entrée . 23
5.3.1 Étalonnage de la puissance d’entrée optique . 24
5.3.2 Détermination de BER ou EBR . 25
5.4 Mesure du niveau de surcharge . 25
5.4.1 Généralités . 25
5.4.2 Étalonnage du niveau de puissance . 26
5.4.3 Détermination du niveau de surcharge . 28
5.4.4 Calcul du niveau de surcharge . 29
6 Incertitudes de mesure . 29
7 Résultats des essais . 29
7.1 Informations requises . 29
7.2 Informations disponibles . 29
Bibliographie . 31

Figure 1 – Système à fibres optiques . 20
Figure 2 – Montage de mesure de la sensibilité en entrée d’un terminal de réception . 23
Figure 3 – Montage de mesure de la sensibilité en entrée d’un amplificateur ou d’un
régénérateur . 24
Figure 4 – Montage de mesure du niveau de surcharge d’un terminal de réception . 27
Figure 5 – Montage de mesure du niveau de surcharge d’un amplificateur ou d’un
régénérateur . 28

Tableau 1 – Temps de surveillance minimal . 25

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
PROCÉDURES D'ESSAI DES SOUS-SYSTÈMES
DE TÉLÉCOMMUNICATIONS À FIBRES OPTIQUES –

Partie 2-1: Systèmes numériques –
Mesure de la sensibilité et de la surcharge d'un récepteur

AVANT PROPOS
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2) Les décisions ou accords officiels de l'IEC concernant les questions techniques représentent, dans la mesure
du possible, un accord international sur les sujets étudiés, étant donné que les Comités nationaux intéressés
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