1、 TIA STANDARD FOTP-236 IEC 61280-2-9 Fibre Optic Communication Subsystem Test Procedures Digital Systems Part 2-9: Optical Signal-to-Noise Ratio Measurement for Dense Wave-Length Multiplexed Systems TIA-455-236 FEBRUARY, 2004 TELECOMMUNICATIONS INDUSTRY ASSOCIATION Representing the telecommunication
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19、 1 Scope 1 2 Normative references .2 3 Definitions2 4 Apparatus 3 4.1 Diffraction grating-based OSA .3 4.2 Michelson interferometer-based OSA.4 4.3 Fabry-Perot-based OSA 4 4.4 OSA performance requirements.5 4.4.1 Wavelength range5 4.4.2 Sensitivity5 4.4.3 Resolution bandwidth (RBW)5 4.4.4 Resolution
20、 bandwidth accuracy6 4.4.5 Dynamic range.6 4.4.6 Scale fidelity7 4.4.7 Polarization dependence7 4.4.8 Wavelength data points7 5 Sampling and specimens8 6 Procedure 8 7 Calculations .8 8 Measurement uncertainty .8 9 Documentation .9 Annex A (informative) Error in measuring signal level due to signal
21、spectral width 10 Bibliography .14 61280-2-9/CDV adopted as TIA-455-236 iiINTERNATIONAL ELECTROTECHNICAL COMMISSION _ FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES Part 2-9: Digital systems Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems FOREWORD 1)
22、The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote international co-operation on all questions concerning standardization in the electri
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28、 rendered responsible for any equipment declared to be in conformity with one of its standards. 6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. The IEC shall not be held responsible for identifying any or all such
29、 patent rights. International Standard IEC 61280-2-9 has been prepared by subcommittee 86C: Fibre optic systems and active devices, of IEC technical committee 86: Fibre optics The text of this standard is based on the following documents: FDIS Report on voting 86C/457/FDIS 86C/479/RVD Full informati
30、on on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 3. Annex A is for information only. The committee has decided that the contents of this publication
31、will remain unchanged until 2008. At this date, the publication will be reconfirmed; withdrawn; 61280-2-9/CDV adopted as TIA-455-236 iii replaced by a revised edition, or amended. IEC 61280-2 consists of the following parts, under the general title Fibre optic communication subsystem test procedures
32、1): Part 2-1: Test procedures for digital systems Receiver sensitivity and overload measurement Part 2-2: Test procedures for digital systems Optical eye pattern, waveform, and extinction ratio Part 2-4: Test procedures for digital systems Bit-rate tolerance measurement Part 2-5: Test procedures for
33、 digital systems Jitter transfer function measurement Part 2-9: Digital systems Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems _ 1)The general title of the IEC 61280 series has changed. Parts 2-1, 2-2, 2-4 and 2-5 were published under the general title Fi
34、bre optic communication subsystem basic test procedures 61280-2-9/CDV adopted as TIA-455-236 ivINTRODUCTION 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
35、parameters are necessary to monitor 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 channe
36、l of a multichannel carrier at 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 m
37、ultichannel interface point. It 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 t
38、he optical spectrum. Wavelength-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 waveshape impairments resulting from polarization
39、-mode dispersion (PMD), and chromatic dispersion. Also, intersymbol interface 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 Recommendation G.692; “Optical interfaces for mult
40、ichannel systems with optical amplifiers.”12)OSNR is also listed in ITU-T Recommendation G.959.1, “Optical transport network physical layer interfaces.” _ 2)Figures in brackets refer to the bibliography. 61280-2-9/CDV adopted as TIA-455-236 1FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES Part 2
41、-9: Digital systems Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems 1 Scope This 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
42、multichannel interface. Because noise measurement is made on an optical spectrum analyzer, the measured noise does not include source relative intensity noise (RIN) or receiver noise. Three implementations for an optical spectrum analyser (OSA) are discussed: a diffraction-grating-based OSA, a Miche
43、lson interferometer-based OSA, and a Fabry-Perot-based OSA. Performance characteristics of the OSA that affect OSNR measurement 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 nomina
44、lly on the grid defined by ITU Recommendation G.694.1. Individual channels may be non-existent because it is a network designed 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 OSN
45、R, the most appropriate noise power value is that at the channel wavelength. However, with a direct spectral measurement, the noise power at the channel wavelength is included in signal power and is difficult to extract. An estimate of the channel noise power can be made by interpolating the noise p
46、ower value between channels. 61280-2-9/CDV adopted as TIA-455-236 2WavelengthOptical powerMissing channelsChannels onthe ITU gridNoiseIEC 2407/02Figure 1 A typical optical spectrum at an optical interface in a multichannel transmission system 2 Normative references None. 3 Definitions 3.1 optical si
47、gnal-to-noise ratio (OSNR) ratio in decibels, from the optical spectrum, defined by the equation rmLog10Log10OSNRBBNPii+= dB (1) where: Piis the optical signal power in watts at the i-th channel. Br is the reference optical bandwidth. Niis the interpolated value of noise power in watts measured in n
48、oise equivalent bandwidth, Bm, 2)()(i +=iiNNN (2) at the i-th channel; i is the wavelength of the I-th channel; is the interpolation offset equal to or less than one-half the ITU grid spacing. 61280-2-9/CDV adopted as TIA-455-236 3(The units for Bm andBrmay be in frequency or wavelength but must be
49、consistent.) 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 the actual filter at its center wavelength. N(i )Ni N(i+ )Pi+ NiIEC 2408/02Figure 2 The OSNR for each channel is derived from direct measurements of the optical spectrum 4 Apparatus The req
