Consideration on the use of OTDRs to measure return loss of single-mode optical fibre connections

The purpose of this document is to describe a round robin on return loss of single mode optical fibre connections. This includes the description of the samples, the test procedures and test instrumentation, results and conclusions.

Überlegungen zur Verwendung von OTDRs zur Messung der Rückflussdämpfung von Einmoden-LWL-Verbindungen

Examen de l'utilisation de la réflectométrie optique dans le domaine temporel (OTDR) pour la mesure de l'affaiblissement de réflexion des connexions en unimodal

Vidiki uporabe OTDR za meritve povratnega slabljenja na povezavah enorodovnih optičnih vlaken

Namen tega dokumenta je opisati medlaboratorijski preskus povratne izgube enorodovnih optičnih povezav.  To vključuje opis vzorcev, preskusne postopke ter preskusne instrumente, rezultate in zaključke.

General Information

Status
Published
Publication Date
31-May-2018
Current Stage
6060 - Document made available
Due Date
01-Jun-2018
Completion Date
01-Jun-2018

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SLOVENSKI STANDARD
SIST-TP CLC/TR 50682:2018
01-september-2018
9LGLNLXSRUDEH27'5]DPHULWYHSRYUDWQHJDVODEOMHQMDQDSRYH]DYDKHQRURGRYQLK
RSWLþQLKYODNHQ

Consideration on the use of OTDRs to measure return loss of single-mode optical fibre

connections

Examen de l'utilisation de la réflectométrie optique dans le domaine temporel (OTDR)

pour la mesure de l'affaiblissement de réflexion des connexions en unimodal
Ta slovenski standard je istoveten z: CLC/TR 50682:2018
ICS:
33.180.01 6LVWHPL]RSWLþQLPLYODNQLQD Fibre optic systems in
VSORãQR general
SIST-TP CLC/TR 50682:2018 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CLC/TR 50682:2018
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SIST-TP CLC/TR 50682:2018
TECHNICAL REPORT CLC/TR 50682
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
June 2018
ICS 33.180.01
English Version
Consideration on the use of OTDRs to measure return loss of
single-mode optical fibre connections

Examen de l'utilisation de la réflectométrie optique dans le Überlegungen zur Verwendung von OTDRs zur Messung

domaine temporel (OTDR) pour la mesure de der Rückflussdämpfung von Einmoden-LWL-Verbindungen

l'affaiblissement de réflexion des connexions en unimodal
This Technical Report was approved by CENELEC on 2018-04-16.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,

Switzerland, Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. CLC/TR 50682:2018 E
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Contents Page

European foreword ....................................................................................................................................... 3

Introduction ................................................................................................................................................... 4

1 Scope ................................................................................................................................................... 5

2 Normative references ......................................................................................................................... 5

3 Terms and definitions ........................................................................................................................ 5

4 Description of Samples ..................................................................................................................... 5

5 Test ...................................................................................................................................................... 6

6 Test results ......................................................................................................................................... 6

7 Conclusions ...................................................................................................................................... 12

Annex A (informative) Test data obtained in the Round Robin .............................................................. 13

Bibliography ................................................................................................................................................ 19

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European foreword

This document (CLC/TR 50682:2018) has been prepared by CLC/TC 86BXA "Fibre optic interconnect, passive

and connectorised components".

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.

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Introduction

The introduction of new types of optical fibre (i.e. ITU-T G.657, EN 60793-2-50 B6 type) and the differences

between manufacturers’ products cause a spread of up to 3 dB in the backscatter values (Bs) of available

telecommunications single mode fibre. The variation in this parameter can lead to large differences in measured

return loss (RL) of connections. This can give issues in field measurement where the fibre type and manufacturer

may be unknown and the Bs may not be updated for each measurement in the OTDR.

To evaluate the real impact of this spread of backscatter vales on return loss measurement, a Round Robin

Test (RRT) was designed by CLC TC86BXA in 2015. “Black-box” connections (i.e. closed boxes with a

connection of two plugs and fibre with similar or different Bs values) were circulated for testing in 2016 and 2017

around several laboratories. The result of this Round Robin is intended to contribute to future specification of

return loss requirements on optical components.
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1 Scope

The purpose of this document is to describe a round robin on return loss of single mode optical fibre connections.

This includes the description of the samples, the test procedures and test instrumentation, results and

conclusions.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes

requirements of this document. For dated references, only the edition cited applies. For undated references, the

latest edition of the referenced document (including any amendments) applies.

EN 61300-3-6:2009, Fibre optic interconnecting devices and passive components - Basic test and measurement

procedures - Part 3-6: Examinations and measurements - Return loss
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
return loss

ratio of the power (Pi) incident on, or entering, the DUT to the total power reflected (Pr) by the DUT, expressed

in decibels
3.2
backscatter value

backscattering level of the OTDR trace is a constant (K) that includes both the Rayleigh backscattering of the

fibre and the OTDR pulse duration
4 Description of Samples

The Device Under Test (DUT) was an optical fibre-to-fibre connection, protected by a box, making the

connection inaccessible to the user. The patch cords used in the DUTs were provided by different manufacturers

to ensure a mix of fibres. The plugs in the connection were either SC/APC or SC/PC style which were terminated

on single fibre cable 50 m in length, and the free ends were terminated with SC/APC plugs in order to create

input/output ports. All the combinations were chosen in order to have a connection RL between 55 dB and

60 dB. Some of these connections were made by mixing fibres with similar BS and others using different BS.

Ten DUTs (black boxes) were made in total. The samples were packed and transported in such a way as to

minimize performance changes during the round robin test and retested at the end of the RRT.

In Table 1, the fibre manufacturers, fibre types and mode field diameters (MFD) of the samples used in the RRT

are listed, together with the backscatter values at 1 310 nm and 1 550 nm. It can be noted that the difference

among BS values is higher at 1 310 nm (~ 2,6 dB), than at 1 550 nm (~ 0,7 dB).
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Table 1 — B and mode field diameter (MFD) values of fibres obtained from manufacturers’ publicly

available datasheets
Fibre Mode Field Diameter B (dB @ B (dB @
S S
Fibre type
Manufacturer (µm) 1310 nm) 1550 nm)
SMF-28e+ LL (G.652.D)
SMF-28 Ultra (G.652.D & 9,2 ± 0,4 at 1 310 nm
-77,0 -82,0
G.657.A1) 10,4 ± 0,5 at 1 550 nm
SMF-28e+ (G.652.D)
CORNING
9,2 ± 0,4 at 1 310 nm
SMF-28 (G.652.D) -77,0 -82,0
10,4 ± 0,8 at 1 550 nm
Elite Bendbright-XS 8,8 ± 0,4 at 1 310 nm
DRAKA -79,1 -81,4
(G.657.A2&B2) 9,8 ± 0,5 at 1 550 nm
9,0 ± 0,4 at 1 310 nm
DRAKA ESMF (G.652.D) -79,4 -81,7
10,1 ± 0,5 at 1 550 nm
AllWave FLEX ZWP 8,9 ± 0,4 at 1 310 nm
OFS -79,6 -82,1
(G.652.D & G.657.A1) 9,9 ± 0,5 at 1 550 nm
5 Test

16 different laboratories (Table 2) tested the return loss of the DUTs. Not every laboratory performed all of the

tests. Each of them was required to set their commercial OTDRs to the B values reported in EN 61300-3-6:2009

(i.e. B ≅ 80 dB for 1 310 nm, B ≅ 82,5 dB for 1 550 nm).
s s

Each connection (i.e. each box) was tested from both entry ports and data was reported on a dedicated form.

The pulse width was not prescribed and could be chosen by each laboratory, depending on the OTDR available.

Where possible, it was recommended to avoid the use of a launch fibre, to limit further uncertainty factors.

Table 2 — Laboratories involved in testing the samples
CommScope, Belgium LEMO F.O.U.R, UK
CommScope, Netherlands Optokon, a.s., Czech Republic
Corning Cable Systems Polska Sp. z o.o., Poland Optotec, Italy
Diamond SA, Switzerland Orange Poland, Poland
EXATEL S.A., Poland Reichle de Massari, Switzerland
FibreFab Ltd, UK SQS Vlaknova optika a.s., Czech Republic
HARTING AG & Co. KG, Germany TDE, Germany
Huber+Suhner AG, Switzerland TIM, Italy
Instytut Łączności, Poland
6 Test results

The combination of the variability in B and the typical commercial OTDR return loss accuracy of +/- 2 dB can

lead to a measurement variation of up to 5 dB.

The samples were retested at the end of the RRT by the originating laboratory and were found to have few

significant changes in characteristics. See Table 3. Boxes 5, 9 and 10 had the highest changes.

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Table 3 — Test results before and after the round robin
Sample Connection Measured RL [dB] Measured RL [dB] RL Difference [dB]
No — OTDR Type Before Testing After Testing
(Before-After)
Launching Port
1 310 nm 1 550 nm 1 310 nm 1 550 nm 1 310 nm 1 550 nm
Box 1 - Port A SC/APC 55,2 57,0 55,7 56,1 -0,6 0,9
Box 1 - Port B SC/APC 56,0 57,4 56,3 56,9 -0,3 0,5
Box 2 - Port A SC/APC 57,8 59,4 57,4 58,3 0,4 1,1
Box 2 - Port B SC/APC 58,1 59,4 57,4 58,3 0,7 1,1
Box 3 - Port A SC/APC 57,9 59,4 57,3 58,8 0,6 0,6
Box 3 - Port B SC/APC 56,8 59,5 56,5 57,7 0,3 1,8
Box 4 - Port A SC/APC 57,5 59,6 57,3 58,1 0,2 1,5
Box 4 - Port B SC/APC 56,4 58,2 56,3 57,7 0,1 0,5
Box 5 - Port A SC/APC 58,3 59,8 58,2 58,5 0,1 1,3
Box 5 - Port B SC/APC 58,4 60,2 58,4 57,5 0,0 2,7
Box 6 - Port A SC/APC 56,9 58,3 57,3 58,5 -0,4 -0,2
Box 6 - Port B SC/APC 57,2 58,0 56,4 57,9 0,8 0,1
Box 7 - Port A SC/APC 58,9 60,7 59,1 60,0 -0,2 0,7
Box 7 - Port B SC/APC 59,0 60,5 58,8 60,4 0,2 0,1
Box 8 - Port A SC/APC 57,2 58,4 56,6 58,4 0,6 0,0
Box 8 - Port B SC/APC 56,2 57,3 55,4 57,5 0,8 -0,2
Box 9 - Port A SC/PC 55,9 56,8 56,2 57,8 -0,3 -1,0
Box 9 - Port B SC/PC 55,2 56,1 56,3 57,0 -1,2 -1,0
Box 10 - Port A SC/PC 63,1 61,1 59,5 61,2 3,6 -0,1
Box 10 - Port B SC/PC 61,2 60,2 60,0 61,0 1,2 -0,8

The aim of using the same BS value was not achieved, since some of the OTDRs used were not capable of

setting this parameter. The collected data has been divided into two different groups, depending on the pulse

width (short or long). Table 4 gives the main test parameters, as declared by each laboratory.

NOTE In this document, short pulse width is defined as ≤ 10 ns, long pulse width is defined as > 10 ns.

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Table 4 — Main test parameters set on each OTDR by the laboratories.
a b
Short Pulse Width Long Pulse Width
Pulse Fibre Pulse Fibre
Bs @ Bs @ Bs @ Bs @
OTDR Model Width launch Width launch
1 310 nm 1 550 nm 1 310 nm 1 550 nm
[ns] [m] [ns] [m]
Ando AQ 7250 10 3 No info No info
Anritsu MW9040B 100 No info 80,0 82,5
Anritsu 9060A 100 - 80,0 82,5
Anritsu 9076 D1 20 - 80 82,5
Anritsu 9076 D1 50 - 80 82,5
Anritsu MT-9083A 3 3 78,5 81,5 20 3 78,5 81,5
Anritsu MT-9083B 10 - 81,5 20 - 78,5
EXFO AXS-100 10 500 79,4 81,9
EXFO AXS-100 10 4 79,4 81,9
EXFO FTB-100B 10 4 79,4 81,9
EXFO FTB-200 10 4 79,4 81,9
EXFO FTB-7200D 100 250 80,0 82,5
EXFO FTB-730 50 - 80,0 82,5
EXFO FTB-1 FTB-730C-SM2-EA 10 - 80 82,5 30 - 80 82,5
EXFO FTB-1 FTB-730-23B-04B-OPM-EA 10 - 80 82,5 50 - 80 82,5
EXFO Maxtester 730C-SM2-EA 10 - 80 82,5 50 - 80 82,5
JDSU 3168 10 100 80,0 82,5
JDSU MTS 6000 30 - 80,0 82,5
JDSU MTS 8000 30 3 81,0 81,0
Luciol LOR 200 2 - 80,0 82,5 30 3 80,0 82,5
NOYES OFL-250 10 4 79,4 81,9
OPTOKON MOT-700D 10 1 000 80 80
TEKTRONIX TFP2 20 382/913 80,0 82,5
Wavetek MTS5100 5 1 000 80,2 81,7 20 1 000 80,2 81,7
Yokogawa AQ1205F 10 - 80 82,5 50 - 80 82,5
Yokogawa AQ7270 10 1 000 No info No info
Yokogawa AQ7275 3 500 80,0 82,5
Short Pulse Width: 2, 3, 5 and 10 ns.
Long Pulse Width: 20, 30, 50 and 100 ns.

In Table 5, the minimum and maximum values and the calculated mean and standard deviation values are given

for each port of the test boxes.
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Table 5 — Minimum, maximum, mean values — Standard deviation
SHORT PULSE WIDTH — SHORT PULSE WIDTH — LONG PULSE WIDTH — LONG PULSE WIDTH —
1 310 nm 1 550 nm 1 310 nm 1 550 nm
MIN MAX MEAN STDEV MIN MAX MEAN STDEV MIN MAX MEAN STDEV MIN MAX MEAN STDEV

[dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB] [dB]

Box 1 Port A
53,4 60,3 55,7 2,07 54,6 60,5 56,3 1,65 53,7 58,2 54,8 1,00 54,3 59,2 55,9 1,14

Box 1 Port B 54,5 61,7 56,5 2,00 55,3 62,9 57,3 1,99 53,5 58,9 55,5 1,13 55,2 60,3 56,7 1,18

Box 2 Port A
56,5 61,7 58,4 1,59 57,6 64,6 59,3 1,73 55,4 61,5 57,5 1,33 57,7 62,8 58,9 1,26

Box 2 Port B 56,7 66,1 58,6 2,24 57,7 63,4 59,5 1,64 55,5 61,4 57,6 1,32 57,7 62,9 59,0 1,30

Box 3 Port A 56,3 63,4 58,4 1,86 57,4 62,4 59,2 1,49 55,3 61,2 57,5 1,35 55,5 62,8 58,8 1,54

Box 3 Port B 55,8 63,0 57,8 1,90 57,2 61,7 58,8 1,39 54,9 60,7 56,8 1,27 57,2 62,3 58,5 1,33

Box 4 Port A
56,0 61,3 57,9 1,62 57,4 65,8 59,2 2,02 55,1 60,9 57,1 1,30 57,3 62,4 58,8 1,25

Box 4 Port B 55,8 61,8 57,6 1,82 57,1 61,9 58,5 1,38 54,6 60,3 56,6 1,21 57,0 61,8 58,1 1,16

Box 5 Port A
55,5 62,6 57,9 2,06 56,0 63,7 58,7 2,10 55,1 60,2 56,8 1,19 56,9 61,1 58,2 1,13

Box 5 Port B 55,3 61,9 57,8 1,97 56,6 63,3 58,5 1,79 51,1 60,1 56,5 1,96 55,8 61,1 57,9 1,33

Box 6 Port A 55,3 65,4 57,8 2,44 56,3 62,8 58,2 1,80 55,3 60,0 56,8 1,11 56,0 61,8 57,9 1,30

Box 6 Port B 55,1 60,8 57,1 1,84 55,8 63,9 57,9 2,03 54,8 59,7 56,4 1,10 56,3 60,6 57,5 1,03

Box 7 Port A
58,3 67,8 60,2 2,20 59,3 65,4 61,3 1,56 57,5 63,1 59,2 1,26 59,2 64,7 60,8 1,24

Box 7 Port B 57,9 65,2 59,8 1,87 59,0 67,0 61,3 1,79 57,4 63,1 59,0 1,32 59,0 64,8 60,8 1,34

Box 8 Port A
54,7 60,8 57,3 1,86 55,6 61,8 57,8 1,81 54,7 59,7 56,3 1,14 56,1 61,1 57,4 1,22

Box 8 Port B 54,3 62,6 56,6 2,25 55,4 61,8 57,6 1,70 54,6 58,9 55,6 1,00 54,2 60,1 56,6 1,32

Box 9 Port A 55,5 64,9 57,2 2,27 56,0 62,3 57,8 1,70 54,5 60,2 56,1 1,30 56,3 60,7 57,4 1,13

Box 9 Port B 54,9 61,3 56,9 1,88 55,7 64,5 57,7 2,25 54,2 59,7 56,0 1,43 55,6 60,6 56,9

...

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