1、BRITISH STANDARDBS EN 4533-002:2006Aerospace series Fibre optic systems Handbook Part 002: Test and measurementThe European Standard EN 4533-002:2006 has the status of a British StandardICS 49.060g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g
2、38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 4533-002:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2006 BSI 2006ISBN 0 580 49347 4National forewordThis British Standa
3、rd was published by BSI. It is the UK implementation of EN 4533-002:2006. The UK participation in its preparation was entrusted by Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology, to Subcommittee ACE/6/-/10, Aerospace Fibre optic systems and equipment.A list of org
4、anizations represented on ACE/6/-/10 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations
5、.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 4533-002July 2006ICS 49.060English VersionAerospace series - Fibre optic systems - Handbook - Part 002:Test and measurementSrie arospatiale - Systmes des fibres optiques - Manueldutilisation -
6、 Partie 002 : Essais et mesuresLuft- und Raumfahrt - Faseroptische Systemtechnik -Handbuch - Teil 002: Tests und MessungenThis European Standard was approved by CEN on 28 April 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving th
7、is EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (Eng
8、lish, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czec
9、h Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN
10、DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 4533-002:2006: E2 Contents Page Foreword3 Introduction .4 1 Scope 5 2 Normative
11、 references 5 3 Problem areas and limitations5 3.1 The problem of testing avionic, multi-mode fibre installations 5 3.2 Limitations of current insertion loss prediction and measurement techniques.6 3.2.1 General6 3.2.2 Harness design 6 3.2.3 Insertion loss measurements.6 3.2.4 Optical time domain re
12、flectometry.7 3.3 The way forward.7 4 Techniques for system design.8 4.1 General8 4.2 Interpretation of component data sheets8 4.3 Computer modelling9 4.4 Matrices . 10 5 Practical testing techniques 13 5.1 General. 13 5.2 Launch conditioning of test sources 13 5.2.1 Distributions 13 5.2.2 How are p
13、ower distributions defined? . 13 5.2.3 What is the launch condition of a source? 13 5.2.4 Why do we need to condition the test source?. 14 5.2.5 Why do we need to condition the light entering the power meter? 15 5.2.6 Optimum launch conditions 15 5.2.7 How can we condition the test source? . 17 5.2.
14、8 Usable power. 19 5.3 Test configurations 20 5.3.1 Preferred methods 20 5.3.2 Similar connectors 20 5.3.3 Dissimilar connectors 21 5.3.4 Accuracies and resolutions. 24 5.3.5 Calibration . 24 5.4 Detector characteristics. 25 5.5 Testing networks 26 5.6 Network testing OTDRs. 27 6 Reporting arrangeme
15、nts 29 Bibliography. 30 EN 4533-002:20063 Foreword This European Standard (EN 4533-002:2006) has been prepared by the European Association of Aerospace Manufacturers - Standardization (AECMA-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard
16、has received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by
17、 January 2007, and conflicting national standards shall be withdrawn at the latest by January 2007. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such p
18、atent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Ita
19、ly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 4533-002:20064 Introduction a) The handbook The handbook draws on the work of the Fibre-Optic Harness Study, part sponsored by the Unite
20、d Kingdoms Department of Trade and Industry, plus other relevant sources. It aims to provide general guidance for experts and non-experts alike in the area of designing, installing, and supporting multi-mode fibre-optic systems on aircraft. Where appropriate more detailed sources of information are
21、referenced throughout the text. It is arranged in 4 parts, which reflect key aspects of an optical harness life cycle, namely: Part 001: Termination methods and tools Part 002: Test and measurement Part 003: Looming and installation practices Part 004: Repair, maintenance and inspection b) Backgroun
22、d It is widely accepted in the aerospace industry that photonic technology offers a number of significant advantages over conventional electrical hardware. These include massive signal bandwidth capacity, electrical safety, and immunity of passive fibre-optic components to the problems associated wi
23、th electromagnetic interference (EMI). To date, the latter has been the critical driver for airborne fibre-optic communications systems because of the growing use of non-metallic aerostructures. However, future avionic requirements are driving bandwidth specifications from 10s of Mbits/s into the mu
24、lti-Gbits/s regime in some cases, i.e. beyond the limits of electrical interconnect technology. The properties of photonic technology can potentially be exploited to advantage in many avionic applications, such as video/sensor multiplexing, flight control signalling, electronic warfare, and entertai
25、nment systems, as well as in sensing many of the physical phenomena on-board aircraft. The basic optical interconnect fabric or optical harness is the key enabler for the successful introduction of optical technology onto commercial and military aircraft. Compared to the mature telecommunications ap
26、plications, an aircraft fibre-optic system needs to operate in a hostile environment (e.g. temperature extremes, humidity, vibrations, and contamination) and accommodate additional physical restrictions imposed by the airframe (e.g. harness attachments, tight bend radii requirements, and bulkhead co
27、nnections). Until recently, optical harnessing technology and associated practices were insufficiently developed to be applied without large safety margins. In addition, the international standards did not adequately cover many aspects of the life cycle. The lack of accepted standards thus lead to a
28、irframe specific hardware and support. These factors collectively carried a significant cost penalty (procurement and through-life costs), that often made an optical harness less competitive than an electrical equivalent. c) The fibre-optic harness study The Fibre-Optic Harness Study concentrated on
29、 developing techniques, guidelines, and standards associated with the through-life support of current generation fibre-optic harnesses applied in civil and military airframes (fixed and rotary wing). Some aspects of optical system design were also investigated. This programme has been largely succes
30、sful. Guidelines and standards based primarily on harness study work are beginning to emerge through a number of standards bodies. Because of the aspects covered in the handbook, European prime contractors are in a much better position to utilise and support available fibre optic technology. EN 4533
31、-002:20065 1 Scope Insertion loss is the most frequent measurement performed on a fibre optic link. The avionic system designer will want to know or predict the insertion loss of a link to determine its performance. Aircraft manufacturers will want to measure the insertion loss of harness components
32、 during assembly and before it is delivered to the customer to highlight faults and to provide a record of the performance of the harness at the beginning of its lifetime (footprinting). The insertion loss will be measured at intervals during the lifetime of the aircraft to discover or identify faul
33、ts and any gradual degradation in performance of the harness. There is, however, one problem. It is difficult to collect reliable and consistent measurements of the insertion loss on any multi-mode fibre optic harness where the distance between components is relatively small (less than 100 metres).
34、The reason is that the insertion loss of a component or a harness depends on the power distribution of the light injected into it. This leads to very large differences in the measured value of the insertion loss 1 depending on the power distribution of the source used to make the measurement. This P
35、art of EN 4533 will explain the measurement problem and the techniques used to overcome them in greater detail. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated referenc
36、es, the latest edition of the referenced document (including any amendments) applies. EN 4533-004, Aerospace series Fibre optic systems Handbook Part 004: Repair, maintenance and inspection. ARP5061, Guidelines for Testing and Support of Aerospace, Fiber Optic, Inter-Connect Systems. 1)3 Problem are
37、as and limitations 3.1 The problem of testing avionic, multi-mode fibre installations The insertion loss of a fibre optic harness can be divided into two contributions. The first is the intrinsic loss of the harness caused by the properties of the materials such as the absorption of the silica of th
38、e fibre core. In the case of multi-mode fibres, this would include the variation in the loss of the component caused by changes in the power distribution. When discussing insertion loss, the term power distribution will be used to describe the spatial and angular variation of the power across the fi
39、bres core rather than the temporal variation of the power along the length of the fibre. The second contribution is the additional loss that is introduced into the harness from extrinsic losses such as misalignment errors in connectors and contamination. The insertion loss of components used in any
40、fibre optic link depends on the power distribution of the light that passes through them. However, in some types of fibre harness, the shape of the power distribution does not change as the light propagates through it and the component insertion loss is independent of its position within the harness
41、. For example, the power distribution in single-mode fibre harnesses is fixed by the fibre parameters and the sources wavelength. Long-haul (a few kilometres between components), multi-mode fibre harnesses also effectively have a fixed power distribution because the distance between components is su
42、fficient for the power distribution to reach an equilibrium state that depends only on the fibre parameters. The insertion loss of a long-haul multi-mode harness component is defined by this equilibrium power distribution. 1) Published by: Society of Automotive Engineers (SAE), 400 Commonwealth Driv
43、e, Warrendale, PA 15096-0001. EN 4533-002:20066 In contrast, short-haul multi-mode fibre harnesses (less than 200 metres), like those found in avionic systems, do not have sufficient distance between components to allow the equilibrium power distribution to be attained. The power distribution enteri
44、ng a component within such a harness will now depend on the original power distribution from the source and changes to this distribution caused by the preceding components of the harness. There are two consequences of this power distribution dependent insertion loss: a) The insertion loss will depen
45、d on the source used to make the measurement. b) The insertion loss of a particular component will depend on its position within the harness. A way of reducing the variation in the measured insertion loss is to use modal filters on the source and power meter that alter the sources power distribution
46、 to a known or standard distribution. If all measurements are made with the same power distribution, the insertion loss value will be much more repeatable. Clause 5 will describe some of these standard distributions and the various techniques that can be used to measure the insertion loss of harness
47、es and their components. 3.2 Limitations of current insertion loss prediction and measurement techniques 3.2.1 General This section outlines some of the limitations of the current design and measurement techniques that are used to determine the insertion loss of multi-mode fibre optic harnesses. (Se
48、e Figure 1) 3.2.2 Harness design It is difficult for fibre optic harness designers to predict with accuracy the harness performance. It is unlikely that insertion loss values of commercially available components will have been measured with a specific power distribution based on the parameters of an
49、y avionic fibre. The designer will therefore usually apply a pessimistic estimate for the insertion loss and obtain a much poorer prediction of the harness performance than may necessarily be the case. This may not be important in simple point-to-point communication links between transmitter and receiver where there can be a very large power budget. However, it will be significant in more complex networks, where there are many connector breaks, or in networks that contain components such as passive star-couplers where the power budget
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