1、ASD STANDARD NORME ASD ASD NORM prEN 3475-811 Edition P 1 October 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: Descriptors: Aerospace indus
2、try, aircraft equipment, terminal lugs, splices ENGLISH VERSION Aerospace series Cables, electrical, aircraft use Test methods Part 811: Unbalance attenuation Srie arospatiale Cbles lectriques usage aronautique Mthode dessai Partie 811 : Affaiblissement de dissymtrie Luft- und Raumfahrt Elektrische
3、Leitungen fr Luftfahrtverwendung Prfverfahren Teil 811: Unsymmetriedmpfung 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 Aerospac
4、e Industry. It has been technically approved by the 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-identi
5、fication of the standard. After examination and review 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
6、then to implement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 31 October 2007 Comments should be sent within six months after the date of publication to ASD-STAN Electr
7、ical Domain Copyright 2007 by ASD-STAN prEN 3475-811:20072 Contents Page Foreword2 1 Scope 3 2 Normative references 3 3 Terms and definitions .3 4 Preparation of specimens.4 5 Apparatus .4 6 Methods 5 6.1 Calibration 5 6.2 LCL measurement5 6.3 LCTL measurement .6 7 Requirements.6 Foreword This stand
8、ard was reviewed by the Domain Technical Coordinator of ASD-STANs Electrical Domain. After inquiries and votes carried out in accordance with the rules of ASD-STAN defined in ASD-STANs General Process Manual, this standard has received approval for Publication. prEN 3475-811:2007 3 1 Scope This stan
9、dard specifies methods for measuring unbalance attenuation signal in common mode converted into differential mode caused by the characteristics of symmetry of transmission cables. Terms relative to this attenuation are defined in Clause 3. It shall be used together with EN 3475-100. 2 Normative refe
10、rences 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, elec
11、trical, aircraft use Test methods Part 100: General. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 longitudinal conversion loss (LCL) the longitudinal conversion loss is defined as being the logarithmic ratio of the signal injected in commo
12、n mode at the near end with the resulting differential signal at the near end from a symmetrical pair The LCL is equal to the attenuation of dissymmetry to the near end when the cable under test is finished with the same impedance that defines for the measurement of the asymmetrical attenuation. (Se
13、e Figure 1) Z DUT Z/4Z VTELLCL = 20 log10TLVEdB NOTE DUT Device Under Test Figure 1 3.2 longitudinal conversion transfer loss (LCTL) the longitudinal conversion transfer loss is defined as being the logarithmic ratio of the signal injected in common mode at the near end with the resulting differenti
14、al signal at the far end distant from a symmetrical pair The LCTL is equal to the attenuation of dissymmetry at the far end added with the attenuation from the cable under test when this one is terminated with the same impedance that defines for the measurement of the attenuation of dissymmetry. (Se
15、e Figure 2) prEN 3475-811:20074 DUT Z/4 Z EL1ZVT2Z/4 VL211 22LCTL = 20 log1021TLVEdB Figure 2 4 Preparation of specimens Test specimen shall be of (100 1) meters length. The ends of the cable under test must be prepared in such way that the assembly of the pairs/quads is maintained. For unscreened t
16、wisted pair cables, it is mandatory to create a defined return common-mode path. This is normally achieved by earthing all other pairs. However, the cable under test may be wound onto a metal drum. In this case the drum, the adjacent pairs and screens, if present, should be earthed. 5 Apparatus HF N
17、etwork Analyser Two impedance transformers with centre tap on the secondary windings available (3 ports baluns) Coaxial cables Different resistors terminations The baluns should have the following characteristics: primary impedance: 50 unbalanced secondary impedance: 100 balanced common-mode port im
18、pedance: high impedance insertion loss: 3 dB maximum return loss secondary: 20 dB minimum return loss, common mode: 10 dB minimum longitudinal balance: 60 dB minimum output signal balance: 50 dB minimum common-mode rejection: 50 dB minimum prEN 3475-811:20075 6 Methods 6.1 Calibration a) For the ref
19、erence line calibration over the whole specified frequency range the same coaxial cables used for the measurements shall be used by connecting them between the analyser output and the input. b) Two identical baluns shall be used for the measurements. The baluns shall be connected back to back on the
20、 symmetrical output side and their attenuation measured over the specified frequency range. A short length connection shall be used (see Figure 3). The calculated insertion loss is recorded as Ilbal,DM. U0Udiff U150 50 Figure 3 c) The attenuation of the common signals of the test balun is measured b
21、y connecting the common-mode port terminals to the differential output terminals of the test balun (see Figure 4). The output terminals of the test balun are short-circuited and connected to the inner conductor of the coaxial test lead. The outer shield of the coaxial test lead should be bonded to t
22、he ground plane. The measured insertion loss is recorded as Ilbal,CM. U0U150 50 Figure 4 Finally the computing correction is: Cor_LCLcal = 3 dB Ilbal,DM Ilbal,CM 6.2 LCL measurement The DUT pair under test should be connected to the differential mode balun output terminals. All unused pairs should b
23、e terminated with the suitable resistors as shown in Figure 5. The loads and the cable shielding should be connected on the same ground plane. prEN 3475-811:20076 Figure 5 6.3 LCTL measurement The DUT pair under test should be connected to the differential mode balun output terminals, and the far-en
24、d to the second differential mode balun. All unused pairs should be terminated with the suitable resistors as shown in Figure 6. The loads and the cable shielding should be connected on the same ground plane. Figure 6 7 Requirements The LCL or LCTL values obtained shall not exceed the values specified in the product standard.
