1、ASD STANDARD NORME ASD ASD NORM prEN 3475-810 Edition P 1 July 2007 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATION Avenue de Tervuren, 270 - B-1150 Brussels - Tel. + 32 2 775 8126 - Fax. + 32 2 763 3565 - www.asd-stan.orgICS: 49.060 Descriptors: ENGLISH VER
2、SION Aerospace series Cables, electrical, aircraft use Test methods Part 810: Structural return loss Srie arospatiale Cbles lectriques usage aronautique Mthodes dessais Partie 810 : Affaiblissement de rflexion structurel Luft- und Raumfahrt Elektrische Leitungen fr Luftfahrtverwendung Prfverfahren T
3、eil 810: Rckfludmpfung This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for the needs of the European Aerospace Industry. It has been technically approved by the
4、experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and revi
5、ew by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN national members have then to implement the EN at national level by giving
6、 the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 31 July 2007 Comments should be sent within six months after the date of publication to ASD-STAN Electrical Domain Copyright 2007 by ASD-STAN prEN 3475-810:20
7、072 Contents Page Foreword2 1 Scope 3 2 Normative references 3 3 Definition 3 4 Preparation of specimens.3 5 Apparatus .3 6 Methods 3 7 Requirements.4 Foreword This standard was reviewed by the Domain Technical Coordinator of ASD-STANs Electrical Domain. After inquiries and votes carried out in acco
8、rdance with the rules of ASD-STAN defined in ASD-STANs General Process Manual, this standard has received approval for Publication. prEN 3475-810:20073 1 Scope This standard specifies methods for measuring structural return loss for digital data transmission cable. It shall be used together with EN
9、3475-100. 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 references, the latest edition of the referenced document (including any amendments) applies. EN 3475-100, Aer
10、ospace series Cables, electrical, 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 repr
11、esent the structural effects of the cable itself relative to its own impedance (Zc). The SRL result is sensitive to how the characteristic impedance is centered about the load impedance. 4 Preparation of specimens Test specimen shall be of 100 metres minimum length. The ends of the cable under test
12、must be prepared in such way that 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 approp riate frequency range, im
13、pedance and balanced at least as 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 cal
14、culation of the fitted characteristic impedance. prEN 3475-810:20074 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
15、 expression: =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 charac
16、teristic impedance (); 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 product standard.
