BS EN IEC 60793-1-49:2018 – TC:2020 Edition
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Tracked Changes. Optical fibres – Measurement methods and test procedures. Differential mode delay
| Published By | Publication Date | Number of Pages |
| BSI | 2020 | 97 |
IEC 60793-49:2018 applies only to multimode, graded-index glass-core (category A1) fibres. The test method is commonly used in production and research facilities, but is not easily accomplished in the field. This document describes a method for characterizing the modal structure of a graded-index multimode fibre. This information is useful for assessing the bandwidth performance of a fibre especially when the fibre is intended to support a range of launch conditions, for example, those produced by standardized laser transmitters. This third edition cancels and replaces the second edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) better alignment with original intent by filling some omissions and therefore improving measurement rigor; b) the measurement of fibres with smaller differential mode delay (and higher modal bandwidth) such as type A1a.3 fibres of IEC 60793-2-10 that are used in constructing OM4 performance category cables; new requirements on specifying detector amplitude and temporal response, specimen deployment conditions, four-quadrant scanning, and uniformity of radial locations for calculating bandwidth. Keywords: modal structure of a graded-index multimode fibre, bandwidth performance
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 55 | undefined |
| 58 | Annex ZA(normative)Normative references to international publicationswith their corresponding European publications |
| 59 | English CONTENTS |
| 61 | FOREWORD |
| 63 | 1 Scope 2 Normative references |
| 64 | 3 Terms and definitions |
| 65 | 4 Apparatus 4.1 Overview |
| 66 | 4.2 Optical source Figures Figure 1 – Example apparatus |
| 67 | 4.3 Probe fibre 4.4 Scanning stage 4.5 Probe to test sample coupling 4.6 Cladding mode stripper 4.7 Detection system |
| 68 | 4.8 Sampler and digitizer 4.9 Computational equipment 4.10 System performance 4.10.1 General |
| 69 | 4.10.2 Pulse temporal stability 4.10.3 System stability frequency limit (SSFL) |
| 70 | 5 Sampling and specimens 5.1 Test sample 5.2 Specimen end-faces 5.3 Specimen length 5.4 Specimen deployment 5.5 Specimen positioning 6 Procedure 6.1 Fibre coupling and system setup |
| 71 | 6.2 Determination of centre 6.3 Measurement of the test sample 6.3.1 Selection of radii and quadrant 6.3.2 Collection of scan data 6.4 Determination of ∆TPULSE and ∆TREF 6.5 Reference test method |
| 72 | 7 Calculations and interpretation of results 7.1 General 7.2 Differential mode delay (DMD) 7.2.1 General 7.2.2 Deconvolution 7.2.3 Pulse folding |
| 73 | 7.2.4 Determination of DMD |
| 74 | 7.3 Minimum calculated effective modal bandwidth 7.3.1 General 7.3.2 Time domain pulse computation |
| 75 | 7.3.3 Calculate the transfer function 7.3.4 Compute the power spectrum 7.3.5 Compute EMBc and minEMBc 7.4 Length normalization 8 Documentation 8.1 Information to be reported |
| 76 | 8.2 Information available upon request 9 Specification information |
| 77 | Annex A (normative)Source spectral width limitation A.1 Limiting the effect of chromatic dispersion (CD) on the value of DMD A.1.1 General A.1.2 Limit CD contribution to DMD to be measured A.1.3 Limit CD contribution to reference width |
| 78 | A.1.4 Adjust ∆TREF to account for CD contribution A.1.5 High-performance DMD fibres and spectral requirements |
| 79 | A.2 Chromatic dispersion in multimode fibres Tables Table A.1 – Worst-case chromatic dispersion |
| 80 | Annex B (informative)Determination of fibre optical centre B.1 General B.2 Method |
| 81 | Figure B.1 – Typical area data from centring waveforms |
| 83 | Annex C (normative)Detection system modal measurement C.1 General C.2 Determination of coupling function C.2.1 Overview C.2.2 Fibre sample and coupling C.2.3 Detector response |
| 84 | C.2.4 Reference response Table C.1 – Theoretical normalized coupling efficiency |
| 85 | C.2.5 Coupling function determination |
| 86 | Annex D (informative)Discussion of measurement details D.1 DMD Figure D.1 – Idealized DMD data |
| 87 | D.2 EMBc calculation |
| 90 | Annex E (informative)Determining DMD weights for EMBc calculation E.1 Selecting a set of weightings E.2 Procedure for generating DMD weightings given encircled flux data |
| 92 | Annex F (informative)EMBc calculation information F.1 Default DMD weightings for transmitters conforming to IEC 60793-2-10 Table F.1 – DMD weightings |
| 93 | F.2 Example method to determine if an adjusted bandwidth (BW) metric is adequate Table F.2 – DMD weightings |
| 95 | Bibliography |
