SIST EN 61280-2-12:2014

Fibre optic communication subsystem test procedures - Part 2-12: Digital systems - Measuring eye diagrams and Q-factor using a software triggering technique for transmission signal quality assessment

EN IEC 61280-2-12 defines the procedure for measuring eye diagrams and Q-factor of optical transmission (RZ and NRZ) signals using software triggering technique as shown in 4.1

Prüfverfahren für Lichtwellenleiter-Kommunikationssysteme - Teil 2-12: Digitale Systeme - Messungen von Augendiagrammen und des Q-Faktors mit einem Software-Triggerverfahren für die Qualitätsbewertung von Übertragungssignalen

Procédures d'essai des sous-systèmes de télécommunication à fibres optiques - Partie 2-12: Systèmes numériques - Mesure des diagrammes de l'oeil et du facteur de qualité à l'aide d'une technique par déclenchement logiciel pour l'évaluation de la qualité de la transmission de signaux

L'IEC 61280-2-12:2014 définit la procédure de mesure des diagrammes de l'oeil et du facteur de qualité de la transmission de signaux optique (RZ et NRZ) à l'aide d'une technique par déclenchement logiciel, présentée en 4.1.
Mots clés: mesure des diagrammes de l'oeil et du facteur de qualité de la transmission de signaux optique (RZ et NRZ), technique par déclenchement logiciel

Postopki preskušanja optičnega komunikacijskega podsistema - 2-12. del: Digitalni sistemi - Merjenje očesnih diagramov in Q-faktorja s tehniko programskega proženja za ocenjevanje kakovosti prenosnih signalov (IEC 61280-2-12:2014)

Standard EN IEC 61280-2-12 določa postopek za merjenje očesnih diagramov in Q-faktorja optičnih prenosnih signalov (RZ in NRZ) s tehniko programskega proženja iz točke 4.1

General Information

• Status: Published
• Publication Date: 12-Aug-2014
• 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-Jul-2014
• Due Date: 18-Sep-2014
• Completion Date: 13-Aug-2014
• Ref Project: EN 61280-2-12:2014 - Fibre optic communication subsystem test procedures - Part 2-12: Digital systems - Measuring eye diagrams and Q-factor using a software triggering technique for transmission signal quality assessment

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 61280-2-12:2014
01-september-2014
3RVWRSNLSUHVNXãDQMDRSWLþQHJDNRPXQLNDFLMVNHJDSRGVLVWHPDGHO
'LJLWDOQLVLVWHPL0HUMHQMHRþHVQLKGLDJUDPRYLQ4IDNWRUMDVWHKQLNR
SURJUDPVNHJDSURåHQMD]DRFHQMHYDQMHNDNRYRVWLSUHQRVQLKVLJQDORY,(&

Fibre optic communication subsystem test procedures - Part 2-12: Digital systems -
Measuring eye diagrams and Q-factor using a software triggering technique for
transmission signal quality assessment
Ta slovenski standard je istoveten z: EN 61280-2-12:2014
ICS:
33.180.01 6LVWHPL]RSWLþQLPLYODNQLQD Fibre optic systems in
VSORãQR general
SIST EN 61280-2-12:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 61280-2-12:2014

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SIST EN 61280-2-12:2014


EUROPEAN STANDARD EN 61280-2-12

NORME EUROPÉENNE

EUROPÄISCHE NORM
July 2014
ICS 33.180.10

English Version
Fibre optic communication subsystem test procedures - Part 2-
12: Digital systems - Measuring eye diagrams and Q-factor using
a software triggering technique for transmission signal quality
assessment
(IEC 61280-2-12:2014)
Procédures d'essai des sous-systèmes de Prüfverfahren für Lichtwellenleiter-Kommunikationssysteme
télécommunication à fibres optiques - Partie 2-12: - Teil 2-12: Digitale Systeme - Messungen von
Systèmes numériques - Mesure des diagrammes de l'oeil et Augendiagrammen und des Q-Faktors mit einem Software-
du facteur de qualité à l'aide d'une technique par Triggerverfahren für die Qualitätsbewertung von
déclenchement logiciel pour l'évaluation de la qualité de la Übertragungssignalen
transmission de signaux (IEC 61280-2-12:2014)
(CEI 61280-2-12:2014)
This European Standard was approved by CENELEC on 2014-06-10. 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, 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: Avenue Marnix 17, B-1000 Brussels
© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN 61280-2-12:2014 E

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SIST EN 61280-2-12:2014
EN 61280-2-12:2014 - 2 -
Foreword
The text of document 86C/1150/CDV, future edition 1 of IEC 61280-2-12, prepared by SC 86C “Fibre
optic systems and active devices” of IEC/TC 86 “Fibre optics” was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN 61280-2-12:2014.

The following dates are fixed:
(dop) 2015-03-10
• 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) 2017-06-10
standards conflicting with the
document have to be withdrawn

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

Endorsement notice
The text of the International Standard IEC 61280-2-12:2014 was approved by CENELEC as a
European Standard without any modification.

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SIST EN 61280-2-12:2014
- 3 - EN 61280-2-12:2014
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

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.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu

Publication Year Title EN/HD Year

IEC 61280-2-2 - Fibre optic communication subsystem test EN 61280-2-2 -
procedures -
Part 2-2: Digital systems - Optical eye
pattern, waveform and extinction ratio
measurement
ITU-T 2012 Optical transport network physical layer - -
Recommendation interfaces
G.959.1

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SIST EN 61280-2-12:2014

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SIST EN 61280-2-12:2014




IEC 61280-2-12

®


Edition 1.0 2014-05




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Fibre optic communication subsystem test procedures –

Part 2-12: Digital systems – Measuring eye diagrams and Q-factor using a

software triggering technique for transmission signal quality assessment




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

optiques –


Partie 2-12: Systèmes numériques – Mesure des diagrammes de l'œil et du

facteur de qualité à l'aide d'une technique par déclenchement logiciel pour

l'évaluation de la qualité de la transmission de signaux










INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX R


ICS 33.180.10 ISBN 978-2-8322-1545-6



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 61280-2-12:2014
– 2 – IEC 61280-2-12:2014 © IEC 2014
CONTENTS

FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Abbreviated terms . 6
4 Software synchronization method and Q-factor . 6
4.1 Example of asynchronous waveform and eye diagram reconstructed by
software triggering technique . 6
4.2 Q-factor formula . 7
5 Apparatus . 9
5.1 General . 9
5.2 Optical bandpass filter . 10
5.3 High frequency receiver . 10
5.4 Clock oscillator . 11
5.5 Electric pulse generator . 11
5.6 Sampling module . 11
5.7 Electric signal processing circuit . 12
5.8 Optical clock pulse generator . 12
5.9 Optical sampling module . 12
5.10 Optical signal processing circuit . 12
5.11 Synchronization bandwidth . 12
5.12 Monitoring system parameters . 13
6 Procedure . 13
6.1 General . 13
6.2 Measuring eye diagrams and Q calculations . 13
Annex A (informative) Example of the signal processing required to reconstruct the
synchronous eye diagram . 15
Annex B (informative) Adequate sampling time width (gate width) . 17
Bibliography . 18

Figure 1 – Asynchronous waveform and synchronous eye diagram of 40 Gbps RZ-
signal reconstructed by software triggering technique . 7
Figure 2 – RZ synchronous eye diagram reconstructed by software triggering
technique, time window, and histogram . 8
Figure 3 – Example of relationship between Q-factor and window width . 8
Figure 4 – Test system 1 for measuring eye diagrams and Q-factor using the software
triggering technique . 9
Figure 5 – Test system 2 for measuring eye diagrams and Q-factor using the software
triggering technique . 10
Figure A.1 – Block diagram of the software triggering module . 15
Figure A.2 – Example of interpolating a discrete spectrum and determining beat
frequency . 16
Figure B.1 – The typical calculated relationship between the adequate sampling time
width (gate width) and the bit rate of the optical signal . 17

Table 1 – Monitoring system parameters . 13

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SIST EN 61280-2-12:2014
IEC 61280-2-12:2014 © IEC 2014 – 3 –

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 2-12: Digital systems –
Measuring eye diagrams and Q-factor using a software triggering
technique for transmission signal quality assessment

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.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is
claimed that compliance with this document may involve the use of patents concerning
software synchronization given in Clause 4 and procedure for calculating eye-diagrams and
Q-factor given in Clause 6.
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured the IEC that they are willing to negotiate
licences either free of charge or under reasonable and non-discriminatory terms and
conditions with applicants throughout the world. In this respect, the statements of these
holders of these patent rights are registered with IEC.

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SIST EN 61280-2-12:2014
– 4 – IEC 61280-2-12:2014 © IEC 2014
For US patent 6,744,496, information may be obtained from:
Alcatel-Lucent
Intellectual Property Business Group
16 Brookside Dr.
Sutton, MA 01590 USA
For Japanese patent 3987001 and US patent 7190752, information may be obtained from:
Nippon Telegraph and Telephone Corporation
9-11, Midori-cho, 3-Chrome Musashino-Shi
Tokyo 180-8585 Japan
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights other than those identified above. IEC shall not be held responsible for
identifying any or all such patent rights.
ISO (www.iso.org/patents) and IEC (http://patents.iec.ch) maintain on-line data bases of
patents relevant to their standards. Users are encouraged to consult the data bases for the
most up to date information concerning patents.
International Standard IEC 61280-2-12 has been prepared by subcommittee 86C: Fibre optic
systems and active devices, of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
CDV Report on voting
86C/1150/CDV 86C/1220/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 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.

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SIST EN 61280-2-12:2014
IEC 61280-2-12:2014 © IEC 2014 – 5 –
INTRODUCTION
Signal quality monitoring is important for operation and maintenance of optical transport
networks (OTN). From the network operator’s point of view, monitoring techniques are
required to establish connections, protection, restoration, and/or service level agreements. In
order to establish these functions, the monitoring techniques used should satisfy some
general requirements:
• in-service (non-intrusive) measurement
• signal deterioration detection (both SNR degradation and waveform distortion)
• fault isolation (localize impaired sections or nodes)
• transparency and scalability (irrespective of the signal bit rate and signal formats)
• simplicity (small size and low cost).
There are several approaches, both analogue and digital techniques, which make it possible
to detect various impairments:
1
• bit error rate (BER) estimation [1,2]
• error block detection
• optical power measurement
• optical SNR evaluation with spectrum measurement [3,4]
• pilot tone detection [5,6]
• Q-factor monitoring [7]
• pseudo BER estimation using two decision circuits [8,9]
• histogram evaluation with synchronous eye diagram measurement [10].
A fundamental performance monitoring parameter of any digital transmission system is its
end-to-end BER. However, the BER can be correctly evaluated only with out of service BER
measurements, using a known test bit pattern in place of the real signal. On the other hand,
in-service measurement can only provide rough estimates through the measurement of digital
parameters (e.g., BER estimation, error block detection, and error count in forward error
correction) or analogue parameters (e.g., optical SNR and Q-factor).
An in-service optical Q-factor monitoring can be used for accurate quality assessment of
transmitted signals on wavelength division multiplexed (WDM) networks. Chromatic dispersion
(CD) compensation is required for Q monitoring at measurement point in CD uncompensated
optical link. However, conventional Q monitoring method is not suitable for signal evaluation
of transmission signals, because it requires timing extraction by complex equipment that is
specific to each BER and each format.
The software triggering technique [11-14] reconstructs synchronous eye-diagram waveforms
without an external clock signal synchronized to optical transmission signal from digital data
obtained through asynchronous sampling. It does not rely on an optical signal’s transmission
rate and data formats (RZ or NRZ). Measuring method of eye diagrams and Q-factor using the
software triggering technique is a cost-effective alternative to BER estimations. With eye
diagrams and Q-factor using software triggering test method, signal quality degradations due
to optical signal-to-noise ratio (OSNR) degradation, to jitter fluctuations and to waveform
distortion can be monitored.
This is one of the promising performance-monitoring approaches for intensity modulated
direct detection (IM-DD) optical transmission systems.

1
 Numbers in square brackets refer to the Bibliography.

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SIST EN 61280-2-12:2014
– 6 – IEC 61280-2-12:2014 © IEC 2014
FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 2-12: Digital systems – Measuring eye diagrams and Q-factor using a
software triggering technique for transmission signal quality assessment



1 Scope
This part of IEC 61280 defines the procedure for measuring eye diagrams and Q-factor of
optical transmission (RZ and NRZ) signals using software triggering technique as shown in
4.1 [14].
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 61280-2-2, Fibre optic communication subsystem basic test procedures – Part 2-2: Test
procedure for digital systems – Optical eye pattern, waveform, and extinction ratio
measurement
ITU-T Recommendation G.959.1: 2012, Optical transport network physical layer interfaces
3 Abbreviated terms
ASE amplified spontaneous emission
BER bit error rate
CD chromatic dispersion
EDFA Er-doped fibre amplifier
IM-DD intensity modulated direct detection
RZ return-to-zero
NRZ non-return-to-zero
OBPF optical bandpass filter
OSNR optical signal-to-noise ratio
OTN optical transport networks
PMD polarization mode dispersion
SNR signal-to-noise ratio
WDM wavelength division multiplexing
4 Software synchronization method and Q-factor
4.1 Example of asynchronous waveform and eye diagram reconstructed by software
triggering technique
Figure 1 shows an example of a 40 Gb/s RZ-synchronous eye diagram constructed from
asynchronous sampled data using the software triggering technique. The inset in Figure 1
shows an asynchronous waveform obtained from the same asynchronous sampled data.

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SIST EN 61280-2-12:2014
IEC 61280-2-12:2014 © IEC 2014 – 7 –
Asynchronous
4
waveform
Sampling frequency: 40,379 MHz (asynchronous)
Eye diagram reconstructed
3
by the software triggering
technique
2
Sampled data
1
0
−1
0 5 10 15 20 25
Time  (ps)

IEC  1198/14
Figure 1 – Asynchronous waveform and synchronous eye diagram of
40 Gbps RZ-signal reconstructed by software triggering technique
4.2 Q-factor formula
As shown in Figure 2, the Q-factor can be calculated from a histogram of “mark” (“1”) and
“space” (“0”) levels in the time window, in which an appropriate time window is established in
a large part of the eye opening. The time window is separated into “mark” (“1”) and “space”
(“0”) levels, the average µ and standard deviation σ of the “space” (“0”) level data and the
0 0
average µ and standard deviation σ of the “mark” (“1”) level data are calculated, and the Q-
1 1
factor is calculated by substituting the obtained µ , σ , µ , and σ into Formula (1).
0 0 1 1
The Q-factor depends on the position of the centre of the time window. For optical
transmission signal quality evaluation, the maximum value obtained by calculating Formula (1)
while changing the position of centre of the time window is defined as the Q-factor.
µ −µ
1 0
(1)
Q=
σ +σ
1 0

The Q-factor also depends on width of the time window. Assuming that the signal waveform is
sinusoidal RZ with duty ratio of 50 % (Figure 3(a)) or sinusoidal NRZ (Figure 3(b)) and σ = σ ,
0 1
calculated relationships between Q-factor and window width are shown in Figure 3(c). A
suitable window width is 0,1 UI or less for an RZ signal and 0,2 UI or less for an NRZ signal.

Amplitude  (arb. unit)

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SIST EN 61280-2-12:2014
– 8 – IEC 61280-2-12:2014 © IEC 2014
6
Mark
Histogram
Time window
5
4
σ
1
µ
1
3
Space
2
1
σ
0
µ
0
0
−1
Time

IEC  1199/14
Figure 2 – RZ synchronous eye diagram reconstructed by
software triggering technique, time window, and histogram
NRZ
RZ
1
1
0,5
0,5
0
0
0 0,2 0,5 0,7 1
0 0,2 0,5 0,7 1


Time  (UI)
Time  (UI)
IEC  1201/14
IEC  1200/14


Figure 3a – Sinusoidal RZ
Figure 3b – Sinusoidal NRZ
with duty 50 %


RZ
20
NRZ


18

16

14

12

10

0 0,1 0,2 0,3 0,4 0,5

Window width
IEC  1202/14

Figure 3c – Calculated relationships between Q-factor and window width
Figure 3 – Example of relationship between Q-factor and window width
Amplitude  (a.u.)
Amplitude  (a.u.)
Q factor  (dB)
Amplitude  (a.u.)

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SIST EN 61280-2-12:2014
IEC 61280-2-12:2014 © IEC 2014 – 9 –
5 Apparatus
5.1 General
Test systems are mainly composed of an optical bandpass filter, a high frequency receiver, a
clock oscillator, an electric pulse generator, a sampling module, an electric signal processing
circuit with an AD converter and a software triggering module (Figure 4); or, an optical
bandpass filter, an optical clock pulse generator, an optical sampling module, an optical signal
processing circuit with an AD converter, a low frequency receiver and software triggering
module (Figure 5).
In the typical case, eye diagram and Q-factor measurements are performed after the optical
amplifier of the repeaters, optical-cross connects, and other nodes, because sufficient signal
power level and CD compensation are required for the Q-factor monitoring.
Repeater or optical switching node
High frequency
receiver
Software triggering
Measurement
module
result
Sampling module
AD converter
Electric signal
Optical
processing circuit
band-pass filter
Electric pulse
generator
Clock oscillator
Eye pattern waveform and Q-factor measuring circuit using
the software triggering technique
Transmission line
IEC  1203/14

Figure 4 – Test system 1 for measuring eye diagrams and
Q-factor using the software triggering technique

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SIST EN 61280-2-12:2014
– 10 – IEC 61280-2-12:2014 © IEC 2014
Repeater or optical switching node
Optical sampling
Software triggering
module
module
Measurement
result
AD converter
Optical band- Optical clock pulse
pass filter generator
Low frequency receiver
Optical signal
processing circuit
Eye pattern waveform and Q-factor measuring circuit
using the software triggering technique
Transmission line

IEC  1204/14
Figure 5 – Test system 2 for measuring eye diagrams and
Q-factor using the software triggering technique
5.2 Optical bandpass filter
The optical bandpass filter (OBPF) should be used to remove unnecessary ASE noise from
the optical amplifier or/and to extract the necessary channel from the WDM signals. The
bandwidth of the optical filter B should be broader than the bit rate of the optical signal. The
opt
shape of the OBPF is shown in ITU-T Recommendation G.959.1: 2012, Figure B.2, where two
parameters, the power suppression ratio of adjacent channel and the central frequency
deviation, are defined.
5.3 High frequency receiver
The high frequency receiver is typically a high-speed photodiode, followed by electrical
amplification. The high frequency receiver is equipped with an appropriate optical connector
to allow connection to the optical interface point, either directly or via an optical jumper cable.
Precise specifications are precluded by the wide variety of possible implementations.
However, the high frequency receiver shall follow the general guideline based on IEC 61280-
2-2 as follows:
a) acceptable input wavelength range, adequate to cover the intended application;
b) responsivity, adequate to produce an eye-pattern;
For example, assume that a non-return-to-zero (NRZ) optical data stream with an average
power of −15 dBm is to be measured. If the sensitivity of the signal processing
...