1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsWB9423_BSI_StandardColCov_noK_AW:BSI FRONT COVERS 5/9/08 12:55 Page 1Fibre optic communicationsubsystem test procedures Part 2-9: Digital systems Optical signal-to-noiseratio measure
2、ment for dense wavelength-divisionmultiplexed systemsBS EN 61280-2-9:2009National forewordThis British Standard is the UK implementation of EN 61280-2-9:2009. It isidentical to IEC 61280-2-9:2009. It supersedes BS EN 61280-2-9:2002 whichis withdrawn.The UK participation in its preparation was entrus
3、ted by Technical CommitteeGEL/86, Fibre optics, to Subcommittee GEL/86/3, Fibre optic systems andactive devices.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 provisions of acontract. Use
4、rs are responsible for its correct application. BSI 2009ISBN 978 0 580 60148 4ICS 33.180.20Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 31 May 2009Amendments is
5、sued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 61280-2-9:2009EUROPEAN STANDARD EN 61280-2-9 NORME EUROPENNE EUROPISCHE NORM April 2009 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektr
6、otechnische Normung Central Secretariat: avenue Marnix 17, B - 1000 Brussels 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61280-2-9:2009 E ICS 33.180.20 Supersedes EN 61280-2-9:2002English version Fibre optic communication
7、 subsystem test procedures - Part 2-9: Digital systems - Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems (IEC 61280-2-9:2009) Procdures dessai des sous-systmes de tlcommunications fibres optiques - Partie 2-9: Systmes numriques - Mesure du rapport signal s
8、ur bruit optique pour les systmes multiplexs rpartition en longueur donde dense (CEI 61280-2-9:2009) Prfverfahren fr Lichtwellenleiter-Kommunikationsuntersysteme - Teil 2-9: Digitale Systeme - Messung des optischen Signal-Rausch-Verhltnisses fr dichte Wellenlngen-Multiplex-Systeme (IEC 61280-2-9:200
9、9) This European Standard was approved by CENELEC on 2009-04-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographic
10、al references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a C
11、ENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungar
12、y, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 61280-2-9:2009EN 61280-2-9:2009 - 2 - Foreword The text of document 86C/823/CDV, future edition 2 of IEC
13、61280-2-9, prepared by SC 86C, Fibre optic systems and active devices, of IEC TC 86, Fibre optics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61280-2-9 on 2009-04-01. This European Standard supersedes EN 61280-2-9:2002. The main changes from EN 61280-2-9:2002 ar
14、e as follows: a paragraph has been added to the scope describing the limitations due to signal spectral width and wavelength filtering; Annex B has been added to further explain error in measuring noise level due to signal spectral width and wavelength filtering. The following dates were fixed: late
15、st date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2010-01-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2012-04-01 Annex ZA has been added by CENELEC. _ Endorsem
16、ent notice The text of the International Standard IEC 61280-2-9:2009 was approved by CENELEC as a European Standard without any modification. _ BS EN 61280-2-9:2009- 3 - EN 61280-2-9:2009 Annex ZA (normative) Normative references to international publications with their corresponding European public
17、ations 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. NOTE When an international publication has
18、 been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 61290-3-1 -1)Optical amplifiers - Test methods - Part 3-1: Noise figure parameters - Optical spectrum analyzer method EN 61290-3-1 20032)IEC 62129 -1)Calibration of optical s
19、pectrum analyzers EN 62129 + corr. December 20062)2006 1)Undated reference. 2)Valid edition at date of issue. BS EN 61280-2-9:2009 2 61280-2-9 IEC:2009 CONTENTS INTRODUCTION.6 1 Scope.7 2 Normative references .8 3 Definition8 4 Apparatus.9 4.1 General .9 4.2 Diffraction grating-based OSA .9 4.3 Mich
20、elson interferometer-based OSA 10 4.4 Fabry-Perot-based OSA 10 4.5 OSA performance requirements 11 4.5.1 General .11 4.5.2 Wavelength range .11 4.5.3 Sensitivity11 4.5.4 Resolution bandwidth (RBW) .11 4.5.5 Resolution bandwidth accuracy .12 4.5.6 Dynamic range 12 4.5.7 Scale fidelity13 4.5.8 Polariz
21、ation dependence .13 4.5.9 Wavelength data points .13 5 Sampling and specimens13 6 Procedure 13 7 Calculations .14 8 Measurement uncertainty .14 9 Documentation .14 Annex A (informative) Error in measuring signal level due to signal spectral width.16 Annex B (informative) Error in measuring noise le
22、vel due to signal spectral width and wavelength filtering.19 Bibliography21 Figure 1 A typical optical spectrum at an optical interface in a multichannel transmission system .8 Figure 2 The OSNR for each channel as derived from direct measurements of the optical spectrum .9 Figure 3 A diffraction gr
23、ating-based OSA .10 Figure 4 A Michelson interferometer-based OSA10 Figure 5 A Fabry-Perot-based OSA11 Figure 6 Illustration of insufficient dynamic range as another source of measurement uncertainty13 Figure A.1 The power spectrum of a 10 Gb/s, 27 1 PRBS signal showing the considerable amount of po
24、wer not captured in a 0,1 nm RBW with 0,64 nm filtering after the signal17 Figure A.2 The spectrum of a 2,5 Gb/s 27 1 PRBS with 0,36 nm filtering with considerably less power outside the 0,1 nm OSA RBW .17 Figure A.3 Signal power error versus RBW for a 10 Gb/s modulated signal18 BS EN 61280-2-9:2009
25、61280-2-9 IEC:2009 3 Figure A.4 Signal power error versus RBW for a 2,5 Gb/s modulated signal.18 Figure B.1 Example for noise filtering between channels for a 200 GHz grid 20 Table A.1 Filtering used in simulation to determine signal power level error.16 Table A.2 RBW to achieve less than 0,1 dB err
26、or in signal power 18 BS EN 61280-2-9:2009 6 61280-2-9 IEC:2009 INTRODUCTION At the optical interfaces within wavelength-division multiplexed (WDM) networks, it is desirable to measure parameters that provide information about the integrity of the physical plant. Such parameters are necessary to mon
27、itor network performance as an integral part of network management. They are also necessary to assure proper system operation for installation and maintenance of the network. Ideally, such parameters would directly correspond to the bit error ratio (BER) of each channel of a multichannel carrier at
28、the particular optical interface. Related parameters such as Q-factor or those calculated from optical eye patterns would provide similar information, that is, they would correlate to the channel BER. However, it is difficult to obtain access to these parameters at a multichannel interface point. It
29、 is necessary to demultiplex the potentially large number of channels and make BER, Q-factor, or eye-diagram measurements on a per-channel basis. In contrast, useful information about the optical properties of the multichannel carrier is readily obtained by measuring the optical spectrum. Wavelength
30、-resolved signal and noise levels provide information on signal level, signal wavelength, and amplified spontaneous emission (ASE) for each channel. Spectral information, however, does not show signal degradation due to wave-shape impairments resulting from polarization-mode dispersion (PMD), and ch
31、romatic dispersion. Also, intersymbol interference and time jitter are not revealed from an optical signal to noise ratio (OSNR) measurement. In spite of these limitations, OSNR is listed as an interface parameter in ITU-T Rec. G.692 11, as an optical monitoring parameter in ITU-T Rec. G.697 2 and i
32、n ITU-T G Rec. Sup. 39 3. _ 1Figures in brackets refer to the bibliography. BS EN 61280-2-9:200961280-2-9 IEC:2009 7 FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES Part 2-9: Digital systems Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems 1 Scope This
33、part of IEC 61280 provides a parameter definition and a test method for obtaining optical signal-to-noise ratio (OSNR) using apparatus that measures the optical spectrum at a multichannel interface. Because noise measurement is made on an optical spectrum analyzer, the measured noise does not includ
34、e source relative intensity noise (RIN) or receiver noise. Three implementations for an optical spectrum analyser (OSA) are discussed: a diffraction-grating-based OSA, a Michelson interferometer-based OSA, and a Fabry-Perot-based OSA. Performance characteristics of the OSA that affect OSNR measureme
35、nt accuracy are provided. A typical optical spectrum at a multichannel interface is shown in Figure 1. Important characteristics are as follows. The channels are placed nominally on the grid defined by ITU Recommendation G.694.1.4 Individual channels may be non-existent because it is a network desig
36、ned with optical add/drop demultiplexers or because particular channels are out of service. Both channel power and noise power are a function of wavelength. For calculating the OSNR, the most appropriate noise power value is that at the channel wavelength. However, with a direct spectral measurement
37、, the noise power at the channel wavelength is included in the signal power and is difficult to extract. An estimate of the channel noise power can be made by interpolating the noise power value between channels. The accuracy of estimating the noise power at the signal wavelength by interpolating th
38、e noise power at an offset wavelength can be significantly reduced when the signal spectrum extends into the gap between the signals and when components such as add-drop multiplexers along the transmission span modify the spectral shape of the noise. These effects are discussed in further detail in
39、Annex B, and can make the method of this document unusable for some situations. In such cases, where signal and noise cannot be sufficiently separated spectrally, it is necessary to use more complex separation methods, like polarization or time-domain extinction, or to determine signal quality with
40、a different parameter, such as RIN. This is beyond the scope of the current document. BS EN 61280-2-9:2009 8 61280-2-9 IEC:2009 WavelengthOptical powerMissing channelsChannels onthe ITU gridNoiseIEC 2407/02Figure 1 Typical optical spectrum at an optical interface in a multichannel transmission syste
41、m 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. IEC 61290-3-1, Optical a
42、mplifiers Test methods Part 3-1: Noise figure parameters Optical spectrum analyzer method IEC 62129, Calibration of optical spectrum analyzers 3 Terms and definitions For the purposes of this document, the following terms and definition apply. 3.1 optical signal-to-noise ratio OSNR ratio in decibels
43、, from the optical spectrum, defined by the equation rmiLog10Log10OSNRBBNPi+= dB, (1) where Piis the optical signal power, in watts, at the i-th channel, Bris the reference optical bandwidth, and BS EN 61280-2-9:200961280-2-9 IEC:2009 9 Niis the interpolated value of noise power, in watts, measured
44、in the noise equivalent bandwidth, Bm, given by 2)()(i +=iiNNN (2) at the i-th channel, where iis the wavelength of the i-th channel, and is the interpolation offset equal to or less than one-half of the ITU grid spacing. (The units for Bmand Brmay be in frequency or wavelength but must be consisten
45、t.) Typically, the reference optical bandwidth is 0,1 nm. See Figure 2. NOTE The noise equivalent bandwidth of a filter is such that it would pass the same total noise power as a rectangular passband that has the same area as the actual filter, and the height of which is the same as the height of th
46、e actual filter at its centre wavelength. N(i )Ni N(i+ )Pi+ NiIEC 2408/02Figure 2 OSNR for each channel as derived from direct measurements of the optical spectrum 4 Apparatus 4.1 General The required apparatus is an optical spectrum analyzer (OSA) with the performance necessary to measure the signa
47、l and noise powers required for Equation (1). Three common ways to implement an OSA are with a diffraction grating, a Michelson interferometer, and a Fabry-Perot etalon. 4.2 Diffraction grating-based OSA A simplified diagram of a diffraction grating-based OSA is shown in Figure 3. The expanded input
48、 light is incident on a rotatable diffraction grating. The diffracted light comes off at an angle proportional to wavelength and passes through an aperture to a photodetector. The size of the input and output apertures and the size of the beam on the diffraction grating determine the spectral width
49、of the resulting filter and therefore the resolution of the OSA. A/D conversion and digital processing provide the familiar OSA display. BS EN 61280-2-9:2009 10 61280-2-9 IEC:2009 PhotodiodeDiffractiongratingDisplayLight inputSlitA/DconverterDigitalprocessingIEC 2409/02Figure 3 Diffraction grating-based OSA 4.3 Michelson interferometer-based OSA Another type of OSA is based on the Michelson
