SIST EN IEC 61280-2-13:2024

SLOVENSKI STANDARD
01-november-2024
Postopki preskušanja optičnega komunikacijskega podsistema - 2-13. del:
Digitalni sistemi - Merjenje velikosti vektorja napake (IEC 61280-2-13:2024)
Fibre optic communication subsystem test procedures - part 2-13: Digital systems -
measurement of error vector magnitude (IEC 61280-2-13:2024)
Prüfverfahren für Lichtwellenleiter-Kommunikationssysteme - Teil 2-13: Digitale Systeme
- Größenmessungen von Fehlervektoren (IEC 61280-2-13:2024)
Procédures d’essai des sous-systèmes de télécommunication fibroniques - Partie 2-13:
Systèmes numériques - Mesure de l’amplitude du vecteur d’erreur (IEC 61280-2-
13:2024)
Ta slovenski standard je istoveten z: EN IEC 61280-2-13:2024
ICS:
33.180.01 Sistemi z optičnimi vlakni na Fibre optic systems in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61280-2-13

NORME EUROPÉENNE
EUROPÄISCHE NORM September 2024
ICS 33.180.10
English Version
Fibre optic communication subsystem test procedures - Part 2-
13: Digital systems - Measurement of error vector magnitude
(IEC 61280-2-13:2024)
Procédures d'essai des sous-systèmes de Prüfverfahren für Lichtwellenleiter-Kommunikationssysteme
télécommunication fibroniques - Partie 2-13: Systèmes - Teil 2-13: Digitale Systeme - Größenmessungen von
numériques - Mesure de l'amplitude du vecteur d'erreur Fehlervektoren
(IEC 61280-2-13:2024) (IEC 61280-2-13:2024)
This European Standard was approved by CENELEC on 2024-08-21. 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
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European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
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CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61280-2-13:2024 E

European foreword
The text of document 86C/1900/CDV, future edition 1 of IEC 61280-2-13, 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 IEC 61280-2-13:2024.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2025-05-21
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-08-21
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 shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61280-2-13:2024 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 61280-2-8 NOTE Approved as EN IEC 61280-2-8

IEC 61280-2-13 ®
Edition 1.0 2024-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic communication subsystem test procedures −

Part 2-13: Digital systems − Measurement of error vector magnitude

Procédures d’essai des sous-systèmes de télécommunication fibroniques –

Partie 2-13: Systèmes numériques – Mesure de l’amplitude du vecteur d’erreur

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10  ISBN 978-2-8322-9403-1

– 2 – IEC 61280-2-13:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Background and terminology . 8
4.1 General . 8
4.2 Vector modulated signals . 9
4.3 Constellation diagram . 10
4.4 Normalization of the reference constellation . 11
4.5 Scaling of the measured vectors . 12
4.6 Error vector magnitude of individual symbols . 12
4.7 Root-mean-square EVM . 13
4.8 Calculation of the scale factor . 14
4.9 Iterative calculation of the scale factor . 15
4.10 EVM for polarization multiplexed signals . 16
5 EVM measurement procedure . 16
5.1 Apparatus . 16
5.2 Preparation of data samples . 17
5.3 Calculation of the RMS EVM . 17
5.3.1 General . 17
5.3.2 Procedure with known reference states . 18
5.3.3 Procedure with unknown reference states . 18
5.4 Reporting . 19
Annex A (informative) Relationship between RMS EVM and Q-factor . 20
Bibliography . 25

Figure 1 – Constellation diagrams of measured QPSK and 16-QAM symbols . 11
Figure 2 – Error vector magnitude D(k) of a single QPSK symbol . 13
Figure A.1 – In-phase and quadrature histograms of a QPSK signal . 22
Figure A.2 – In-phase and quadrature histograms of a 16-QAM signal . 23

Table A.1 – Q-factor parameters for a QPSK signal . 22
Table A.2 – Q-factor parameters for a 16-QAM signal . 24

IEC 61280-2-13:2024 © IEC 2024 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 2-13: Digital systems – Measurement of error vector magnitude

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61280-2-13 has been prepared by subcommittee 86C: Fibre optic systems and active
devices, of IEC technical committee 86: Fibre optics. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
86C/1900/CDV 86C/1924/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

– 4 – IEC 61280-2-13:2024 © IEC 2024
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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 document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IEC 61280-2-13:2024 © IEC 2024 – 5 –
INTRODUCTION
The error vector magnitude (EVM) is a single, real-valued parameter that characterizes the
signal quality of n-state amplitude phase shift keyed (n-APSK) signals, which are also known
as vector modulated signals. Similar to the Q-factor used for intensity-modulated
directly-detected optical signals, it measures the average deviations of the transmitted signal
states from their ideal values. These deviations can be caused by noise and by linear and
nonlinear waveform distortions. The EVM is therefore a useful quantity to characterize the
quality of transmitted source signals at the input of a transmission system or the quality of
received signals at the output of a transmission system [1] .
Despite the fact that the EVM is often reported by commercial optical modulation analysers,
there are only a few standards that define a procedure for calculating the EVM of optical signals.
ITU-T Recommendation G.698.2 [2], for example, specifies a maximal EVM value for
polarization-multiplexed 100 Gbit/s QPSK signals generated by an optical transmitter at the
input of a DWDM transmission system. These recommendations provide detailed instructions
for numerical signal processing steps that are to be performed on the received signal before
the EVM is calculated. The steps include removal of undesired frequency and phase offsets,
spectral filtering, DC offset removal, and even the addition of artificial noise to the signal.
Similarly, OIF Implementation Agreement OIF-400ZR-01.0 [3] describes a set of signal
processing steps for determining the EVM in polarization-multiplexed 400 Gbit/s 16-QAM
signals, which include the addition of artificial noise, but does not specify a maximal EVM value
for the transmitted signals at the input of the transmission system.
The detailed signal processing steps defined in ITU-T G.698.2 and in OIF-400ZR-01.0 are
specific to the particular modulation formats and to the applications considered in these
documents. They are not applicable to arbitrary n-APSK signals or to other applications.
This document specifies a general procedure for calculating the EVM of optical n-APSK signals
from a set of transmitted and properly received symbols. It does not specify any signal
processing steps necessary to extract the symbols from the raw received signals or optional
processing steps impacting the signal quality. This document rather defines the normalization
of the reference states used in the EVM calculations as well as a procedure for proper scaling
of the measured signal states. It is intended to serve as a reference for instrument vendors,
transmission equipment manufacturers, and users of such instruments and transmission
equipment.
The procedures described in this document apply to single-polarized optical signals as well as
to conventional polarization-multiplexed signals with independently modulated polarization
tributaries, which are often referred to as three-dimensionally (3-D) coded signals. In general,
it is not advisable to apply these procedures without modifications to four-dimensionally (4-D)
coded signals, in which optical amplitude, phase and polarization state are simultaneously
modulated to encode the information data [4]. At the time of writing, procedures for calculating
the EVM of 4-D coded signals were still under study.

___________
Numbers in brackets refer to the Bibliography.

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FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 2-13: Digital systems – Measurement of error vector magnitude

1 Scope
This part of the IEC 61280-2 series defines a procedure for calculating the root-mean-square
error vector magnitude of optical n-APSK signals from a set of measured symbols. It specifically
defines the normalization of the reference states and a procedure for optimal scaling of the
measured symbol states.
The procedure described in this document applies to single-polarized optical signals as well as
to conventional polarization-multiplexed signals with independently modulated polarization
tributaries. In general, it is not advisable to apply these procedures without modification to
signals, in which optical amplitude, phase, and polarization state are simultaneously modulated
to encode the information data.
This document does not specify any signal processing steps for extracting the symbols from
the received optical signals, because these steps depend on the optical receiver and can vary
with the type of the transmitted n-APSK signal. These and optional additional signal processing
steps are defined in application-specific documents.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
digital modulation
modulation of an optical sinusoidal carrier by a digital signal
Note 1 to entry: Digital modulation is generally an amplitude shift keying, a frequency shift keying, a phase shift
keying or their combination.
[SOURCE: IEC 60050-713:1998, 713-07-12, modified – addition of "optical".]
3.2
binary (digital) signal
digital signal in which each signal element has one of two permitted discrete values
[SOURCE: IEC 60050-704:1993, 704-16-03]

IEC 61280-2-13:2024 © IEC 2024 – 7 –
3.3
n-ary (digital) signal
digital signal in which each signal element has one of n permitted discrete values
[SOURCE: IEC 60050-704:1993, 704-16-05]
3.4
n-state amplitude phase shift keying
n-APSK
digital modulation in which each element of a modulating signal is represented by one of n
specified combinations of phase and amplitude of a sinusoidal oscillation
[SOURCE: IEC 60050-713:1998, 713-07-13, modified – Note 1 to entry deleted.]
3.5
quadrature phase shift keying
QPSK
quadrature phase modulation phase shift keying in which the phase shift takes four values
that are multiples of 90°
[SOURCE: IEC 60050-702:2018, 702-06-43]
3.6
n-state quadrature amplitude modulation
n-QAM
an n-state amplitude phase shift keying which can be obtained by amplitude shift keying of two
carriers in quadrature, the modulated signals being added
2p
Note 1 to entry: In some cases, n is equal to 2 , where p is an integer, and the signal constellation points form a
square (e.g. for square n-QAM).
[SOURCE: IEC 60050-713:1998, 713-07-14, modified – Note 1 to entry added.]
3.7
signal constellation (in digital modulation)
scatter of n points representing in an amplitude-phase diagram the modulated signal in n-state
amplitude phase shift keying
Note 1 to entry: The signal constellation is often plotted in a two-dimensional IQ diagram, in which the two axes
represent the in-phase and quadrature components of the amplitude phase shift keyed signals.
[SOURCE: IEC 60050-713:1998, 713-07-15, modified – Note 1 to entry added.]
3.8
input signal (of a transmission system)
transmitted source signal
signal applied to the input port of the sending terminal equipment of a transmission system
[SOURCE: IEC 60050-704:1993, 704-04-11]
3.9
reference signal (of a transmission system)
ideal undistorted version of the transmitted source signal

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3.10
output signal (of a transmission system)
received source signal
signal emitted from an output port of the receiving terminal equipment of a transmission system
Note 1 to entry: Ideally, the output signal of a transmission system should be an undistorted version of the
corresponding input signal.
[SOURCE: IEC 60050-704:1993, 704-04-12]
3.11
polarization multiplex transmission
polarization multiplexed transmission
method of transmission employing multiplexing of two orthogonally polarized signals at the input
terminal of a transmission path and complementary demultiplexing at the output terminal
[SOURCE: IEC 60050-704:1992, 704-08-09, modified – "polarization" added to the term; "of
two orthogonally polarized signals" added to the definition.]
3.12
decision circuit (for a digital signal)
circuit that decides the probable value of a signal element of a received digital signal
[SOURCE: IEC 60050-704:1992, 704-16-12]
3.13
symbol (in digital modulation)
one of the n states of the modulated signal in n-state amplitude phase shift keying
3.14
error vector magnitude
EVM
difference between the measured signal and a reference
Note 1 to entry: A reference is a perfectly modulated signal.
[SOURCE: ISO/IEC 24769-2:2013, 3.1.1]
3.14.1
RMS error vector magnitude
EVM
rms
E
rms
root-mean-square average of the error vector magnitudes of N symbols of an n-APSK signal
Note 1 to entry: The value of the RMS EVM is greater than zero and is usually expressed in percent.
4 Background and terminology
4.1 General
Clause 4 provides background information on the EVM calculations and defines the terminology
used in this document.
The error vector magnitude (EVM) is a single, real-valued parameter that measures the average
deviations of the various signal states in n-state amplitude phase shift keyed (n-APSK) signals
from their ideal values. Its value is zero for an ideal n-APSK signal and larger than zero for real
(i.e. distorted) n-APSK signals. The EVM is frequently expressed in percent.

IEC 61280-2-13:2024 © IEC 2024 – 9 –
Frequently, n-APSK signals are also referred to as vector modulated signals (see 4.2), because
they can be represented as vectors in a two-dimensional constellation diagram, as described
in 4.3. The average EVM of a transmitted signal is determined from a fairly large number of
transmitted symbols (e.g. larger than 1 000) by first calculating the deviation of the transmitted
state (i.e. the measured state) from its corresponding ideal state individually for each
transmitted symbol, as described in 4.6, and then averaging these deviations as the root-mean-
square of the individual deviations, as described in 4.7.
The resulting quantity is usually referred to as the root-mean-square EVM and abbreviated as
RMS EVM or EVM . The RMS EVM can be viewed as a generalization of the Q-factor, which
rms
is often used to characterize the quality of binary and n-ary intensity-modulated signals. In fact,
RMS EVM and Q-factor are closely related, as described in Annex A.
Important elements of the EVM calculation are the normalization of the reference states, which
is specified in 4.4, and the scaling of the measured states, which is specified in 4.5 and 4.8.
4.2 Vector modulated signals
In general, vector modulated signals are composed of an in-phase component, characterized
by a time-varying amplitude A (t), and a quadrature component, characterized by a time-varying
I
amplitude A (t). Both components are modulated on the same optical carrier frequency, with
Q
the optical phase of the quadrature component being shifted by 90° relative to the in-phase
component. Hence, the time-varying optical amplitude of vector modulated signals can be
represented by a complex function A (t), as shown in Formula (1).
c
j ωt+φ ()t
[ ]
ss

A t P At+ jeA t
( ) ( ) ( ) (1)
c SI Q

where
P is the average optical power of the signal;
S
A (t) is the in-phase component of the modulated signal;
I
A (t) is the quadrature component of the modulated signal;
Q
ω = 2πf is the angular frequency of the unmodulated optical signal (i.e. optical carrier);
s s
φ (t) represents additional optical phase variations.
s
2 2
NOTE 1 In Formula (1), the amplitudes A (t) and A (t) are normalized so that the time average is
I Q I Q
equal to 1. This normalization is different from the one used for calculating the EVM.
Equivalently, A (t) can be represented by a 2-dimensional vector A (t), as shown in Formula (2),
c v
where A (t) and A (t) define the components of this vector.
I Q

At( )
I
j ωt+φ ()t
[ ]
ss
A tP= e
( )  (2)
vS
At
( )

Q

In quadrature phase shift keying (QPSK), for example, A (t) and A (t) are independent binary
I Q
amplitude modulated signals (whose symbol periods are properly synchronized), whereas in
16-state quadrature amplitude modulation (16-QAM), A (t) and A (t) are both quaternary
I Q
amplitude modulated signals.
=
– 10 – IEC 61280-2-13:2024 © IEC 2024
NOTE 2 Vector modulated signals are often generated by two independent optical amplitude modulators (e.g. Mach-
Zehnder modulators) that are connected in parallel to the same light source and operated in such a way that the
optical phase in one of the modulators is delayed by 90° relative to that in the other modulator. More information on
the generation and detection of vector modulated signals can be found in IEC TR 61282-16 [6].
4.3 Constellation diagram
The time varying signal components A (t) and A (t) of a vector modulated signal can be plotted
I Q
in a two-dimensional graph, according to Formula (2). Typically, the abscissa represents the in-
phase component A (t) and the ordinate the quadrature component A (t). In general, these plots
I Q
display only one pair of amplitude values A t ,A t for each transmitted symbol, which
( ) ( )
I k Q k

corresponds to a two-dimensional state vector S(k), as shown in Formula (3).
A t
( )
I k
S k =
( ) (3)

At
( )
Q k
where
k is an integer, with k = 1, 2, 3, …, N.
The time t at which the amplitudes A (t) and A (t) are sampled shall be chosen to best represent
k I Q
the state of the transmitted n-APSK symbol. However, no decision shall be made on the
probable value of the transmitted symbol (i.e. the samples shall be taken prior to a decision
circuit). Moreover, the signal amplitudes of all analysed symbols shall be sampled at the same
position within each symbol period T , so that all sampling times are spaced by an integer
s
multiple of T , as described by Formula (4).
s
t kT+Δ t
(4)
k s
where
Δt is the time offset in each symbol period;
k is an integer, with k = 1, 2, 3, …, N.
The scatter plot of the state vectors S(k) of a vector modulated signal is called a constellation
diagram. Figure 1 displays the constellation diagrams of two widely used n-APSK signals: a
transmitted QPSK signal and a transmitted square 16-QAM signal.
NOTE The signal amplitudes displayed in Figure 1 are scaled according to the procedures described in 4.5 and 4.8.
=
IEC 61280-2-13:2024 © IEC 2024 – 11 –

a) QPSK b) Square 16-QAM
Key
Solid black dots Measured signal states (scaled as described in 4.5 and 4.8)
White crosses Reference states (see 4.4)
Dashed lines Midpoints between the in-phase and quadrature components of the reference states
Figure 1 – Constellation diagrams of measured QPSK and 16-QAM symbols
4.4 Normalization of the reference constellation
The signal constellation of an ideal n-APSK signal is represented by n different points in the
constellation diagram, which correspond to n different reference vectors R(m), m = 1, 2, …, n.
The reference vectors shall be normalized so that the longest vector has unity length, as sh
...