1、BS EN3475-810:2009ICS 49.06NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAerospace series Cables, electrical,aircraft use TestmethodsPart 810: Structural return loss0This British Standardwas published under theauthority of the StandardsPolicy and StrategyCommi
2、ttee on 31 March2009 BSI 2009ISBN 978 0 580 62412 4Amendments/corrigenda issued since publicationDate CommentsBS EN 3475-810:2009National forewordThis British Standard is the UK implementation of EN 3475-810:2009.The UK participation in its preparation was entrusted to TechnicalCommittee ACE/6, Aero
3、space avionic electrical and fibre optictechnology.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance wit
4、h a British Standard cannot confer immunityfrom legal obligations.BS EN 3475-810:2009EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 3475-810February 2009ICS 49.060English VersionAerospace series - Cables, electrical, aircraft use - Testmethods - Part 810: Structural return lossSrie arospatiale -
5、Cbles lectriques usagearonautique - Mthodes dessais - Partie 810:Affaiblissement de rflexion structurelLuft- und Raumfahrt - Elektrische Leitungen frLuftfahrtverwendung - Prfverfahren - Teil 810:RckfludmpfungThis European Standard was approved by CEN on 11 July 2008.CEN members are bound to comply w
6、ith the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this 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 CEN Management Ce
7、ntre or to any CEN member.This European Standard exists in three official versions (English, 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 CEN Management Centre has the same status as theofficial
8、 versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia,
9、 Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Me
10、mbers.Ref. No. EN 3475-810:2009: EBS EN 3475-810:2009EN 3475-810:2009 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Definition 44 Preparation of specimens .45 Apparatus .46 Methods 47 Requirements .5BS EN 3475-810:2009EN 3475-810:2009 (E) 3 Foreword This document (EN 3475-810:2009
11、) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has received the approval of the National Associations and the Official Services of th
12、e member countries of ASD, 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 August 2009, and conflicting national standards shall be withdrawn at the latest by Aug
13、ust 2009. 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 patent rights. According to the CEN/CENELEC Internal Regulations, the national standards or
14、ganizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
15、 Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 3475-810:2009EN 3475-810:2009 (E) 4 1 Scope This standard specifies methods for measuring structural return loss for digital data transmission cable. It shall be used together with EN 3475-100. 2 Normative referen
16、ces The following referenced documents are indispensable for the application 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 3475-100, Aerospace series Cables, electri
17、cal, aircraft use Test methods Part 100: General EN 3475-805, Aerospace series Cables, electrical, aircraft use Test methods Part 805: Characteristic impedance 3 Definition The structural return loss is used for quantifying the level of the reflected signal and to represent the structural effects of
18、 the cable itself relative to its own impedance (Zc). The SRL result is sensitive to how the characteristic impedance is centred about the load impedance. 4 Preparation of specimens Test specimen shall be of 100 metres minimum length. The ends of the cable under test must be prepared in such way tha
19、t the assembly of the pairs/quads is maintained. The measurements may be performed on production drums and/or on the final delivery package from one direction. 5 Apparatus HF Network Analyser. One impedance transformer (balun) with the appropriate frequency range, impedance and balanced at least as
20、well as the pair under test facilitates making measurements on symmetric pairs under balanced conditions. 6 Methods The SRL is a calculated parameter. The SRL is obtained from the measured complex impedance open and short circuit, see EN 3475-805 Method C and the calculation of the fitted characteri
21、stic impedance. BS EN 3475-810:2009EN 3475-810:2009 (E) 5 Fitted characteristic impedance calculation: The following formula gives the cable characteristic impedance module in function of the frequency f (Hz). 2/3322/110fKfKfKKZf += The K0to K3coefficients are extracted from the following expression
22、: =32101312/51212/312/51212/311212/31112/31112/3/1/1/1/111111111111111KKKKfffffffffffffffNfZfZfZZNiiNiiNiiNiiNiiNiiNiiNi iNiiNiiNi iNiiNiiNi iNiiNiisoNi isoNiisoNisowhere Zo/s is the measured complex impedance obtained from open and short circuit measurement Zf (); Zf is the fitted characteristic im
23、pedance (); f is the frequency (Hz); N is the number of measured points. Structural return loss calculation: The SRL for cable pairs is obtained by the formula: fsofsoZZZZSRL+=/log 20 where SRLis expressed in dB. 7 Requirements The SRL values obtained shall not exceed the values specified in the pro
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