IEC TR 61282-10:2013

Fibre optic communication system design guides - Part 10: Characterization of the quality of optical vector-modulated signals with the error vector magnitude

IEC/TR 61282-10:2013(E) defines the error vector magnitude (EVM) as a metric for quantifying the quality of an optical vector-modulated (modulation of phase and possibly magnitude) signal from a transmitter or optical transmission link. The considerations required for reproducible measurement results are detailed. The relationships with other related parameters from constellation diagram analysis like error vector, phase error, magnitude error, I-Q offset and time-resolved EVM are described, as well as the relationship between EVM and Q-factor. Key words: error vector magnitude (EVM), quality of an optical vector-modulated signal The contents of the corrigendum of April 2013 have been included in this copy.

General Information

• Status: Published
• Publication Date: 09-Jan-2013
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: SC 86C - Fibre optic systems and active devices
• Current Stage: PPUB - Publication issued
• Start Date: 15-Mar-2013
• Completion Date: 10-Jan-2013

Relations

• Corrected By: IEC TR 61282-10:2013/COR1:2013 - Corrigendum 1 - Fibre optic communication system design guides - Part 10: Characterization of the quality of optical vector-modulated signals with the error vector magnitude
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC/TR 61282-10 ®
Edition 1.0 2013-01
TECHNICAL
REPORT
colour
inside
Fibre optic communication system design guides –
Part 10: Characterization of the quality of optical vector-modulated signals
with the error vector magnitude

IEC/TR 61282-10:2013(E)
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IEC/TR 61282-10 ®
Edition 1.0 2013-01
TECHNICAL
REPORT
colour
inside
Fibre optic communication system design guides –

Part 10: Characterization of the quality of optical vector-modulated signals

with the error vector magnitude

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
V
ICS 33.180.01 ISBN 978-2-83220-567-9

– 2 – TR 61282-10 © IEC:2013(E)
CONTENTS
FOREWORD . 4
0 Introduction . 6
0.1 Introduction to vector modulated signals . 6
0.2 Digital coding with vector modulation . 6
0.2.1 General . 6
0.2.2 Constellation diagram . 7
0.2.3 IQ diagram . 7
0.3 Polarization multiplexing . 8
0.4 Error vector . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 Error vector magnitude calculations and conditions . 10
4.1 Reference vector assignment . 10
4.2 Normalization of the measured data . 10
4.3 Conditions to be specified with EVM . 11
rms
5 Apparatus for measuring vector modulated signals . 11
5.1 Coherent detector. 11
5.2 Local oscillator . 12
5.2.1 Detection based on electrical real-time sampling . 12
5.2.2 Detection based on optical equivalent-time sampling . 13
5.2.3 One-symbol delayed interferometer . 16
5.2.4 Constellations of non-differential and differential phase modulation
formats . 17
5.3 Digital postprocessing . 18
5.3.1 Impairment compensation . 18
5.3.2 Relative timing skew . 19
5.3.3 IQ phase angle distortion . 19
5.3.4 Offset and relative gain distortion . 20
5.3.5 Polarization alignment . 21
5.3.6 Corrected results . 21
5.3.7 Phase tracking (intradyne detection) . 21
5.3.8 Demodulation (optional) . 22
6 Additional measurement parameters to characterize special details of the signal . 23
6.1 Time-resolved EVM . 23
6.2 EVM with reference filter . 25
6.3 Magnitude error . 26
6.4 Phase error . 26
6.5 I-Q gain imbalance . 27
6.6 I-Q offset . 27
6.7 Quadrature error . 27
Annex A (informative) Relationship between EVM and Q factor . 29
Annex B (informative) Details and implementations of vector signal measurement . 30
Bibliography . 31

TR 61282-10 © IEC:2013(E) – 3 –
Figure 1 – Constellation diagram for QPSK coding . 7
Figure 2 – IQ diagram for the same QPSK coding . 8
Figure 3 – Relationship of error vector to reference vector and measured signal vector
in the constellation diagram . 8
Figure 4 – Block diagram of the main functions for vector signal measurement . 11
Figure 5 – Configuration based on coherent detection with a local oscillator . 12
Figure 6 – Configuration for linear optical sampling. 14
Figure 7 – Schematic comparison of real-time sampling and equivalent-time sampling
to observe a repetitive signal pattern . 16
Figure 8 – One-symbol delayed interferometer for detecting differential phase
modulation . 17
Figure 9 – Simulation of an ideal (D)QPSK signal, represented as a constellation
diagram displaying the absolute phase and amplitude of the optical field (left) . 18
Figure 10 – Simulation of a (D)QPSK signal distorted with 10° IQ-quadrature error . 18
Figure 11 – Calculated influence of impairment . 19
Figure 12 – Error in I and Q determination from phase angle deviation . 19
Figure 13 – Calculated influence of impairment . 20
Figure 14 – Calculated influence of impairment . 21
Figure 15 – IQ-diagram with indicated reference constellation and exemplary error
vectors (left) and time domain plot of the EVM values for each measured sample (right). 23
Figure 16 – Measured time-resolved EVM plots of a 28 GBd QPSK signal affected by
8 ps skew . 24
Figure 17 – Noise-averaged IQ-diagrams and time-resolved EVM plots of a 28 GBd
QPSK signal with 0 p skew (top) and 8 ps skew (bottom) . 25
Figure 18 – Eye-diagram of reference with steep transitions; measured signal I-Q
diagram with symbols at decision time; EVM at symbol decision time (red) and EVM for
all sample points (blue) . 26
Figure 19 – Eye-diagram of reference with raised-cosine filtering; measured signal I-Q
diagram with symbols at decision time; EVM at symbol decision time (red) and EVM for
all sample points (blue) . 26

Table B.1 – Methods for measuring vector modulated optical signals . 30

– 4 – TR 61282-10 © IEC:2013(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES –

Part 10: Characterization of the quality of optical vector-modulated
signals with the error vector magnitude

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