1、BSI Standards PublicationFibre optic communication subsystem test proceduresPart 2-12: Digital systems Measuring eye diagrams and Q-factor using a software triggering technique for transmission signal quality assessmentBS EN 61280-2-12:2014National forewordThis British Standard is the UK implementat
2、ion of EN 61280-2-12:2014. It isidentical to IEC 61280-2-12:2014.The UK participation in its preparation was entrusted by TechnicalCommittee GEL/86, Fibre optics, to Subcommittee GEL/86/3, Fibre optic systems and active devices.A list of organizations represented on this committee can be obtained on
3、request to its secretary.This publication does not purport to include all the necessary provisions ofa contract. Users are responsible for its correct application. The British Standards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 78803 1ICS 33.180.10Compliance with a Briti
4、sh Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 July 2014.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN 61280-2-12:2014EUROPEAN STANDARD NORME
5、EUROPENNE EUROPISCHE NORM EN 61280-2-12 July 2014 ICS 33.180.10 English Version Fibre optic communication subsystem test procedures - Part 2-12: Digital systems - Measuring eye diagrams and Q-factor using a software triggering technique for transmission signal quality assessment (IEC 61280-2-12:2014
6、) Procdures dessai des sous-systmes de tlcommunication fibres optiques - Partie 2-12: Systmes numriques - Mesure des diagrammes de loeil et du facteur de qualit laide dune technique par dclenchement logiciel pour lvaluation de la qualit de la transmission de signaux (CEI 61280-2-12:2014) Prfverfahre
7、n fr Lichtwellenleiter-Kommunikationssysteme - Teil 2-12: Digitale Systeme - Messungen von Augendiagrammen und des Q-Faktors mit einem Software-Triggerverfahren fr die Qualittsbewertung von bertragungssignalen (IEC 61280-2-12:2014) This European Standard was approved by CENELEC on 2014-06-10. CENELE
8、C 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 bibliographical references concerning such national standards may be obtained on app
9、lication to the CEN-CENELEC Management Centre 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 CENELEC member into its own language and notified to the CEN-C
10、ENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary,
11、Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Eu
12、ropisches Komitee fr Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members. Ref. No. EN 61280-2-12:2014 E BS EN 61280-2-12:2014EN 61280-2-12:2014 - 2 - For
13、eword The text of document 86C/1150/CDV, future edition 1 of IEC 61280-2-12, 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 approved by CENELEC as EN 61280-2-12:2014. The following dates are fixed: latest dat
14、e by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2015-03-10 latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2017-06-10 Attention is drawn to the possibility th
15、at some of the elements of this document may be the subject of patent rights. CENELEC and/or CEN shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 61280-2-12:2014 was approved by CENELEC as a European Standard w
16、ithout any modification. BS EN 61280-2-12:2014- 3 - EN 61280-2-12:2014 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in whole or in part, are normatively referenced in this document and are indispensabl
17、e for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
18、EN/HD applies. NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu Publication Year Title EN/HD Year IEC 61280-2-2 - Fibre optic communication subsystem test procedures - Part 2-2: Digital systems - Optical eye pattern
19、, waveform and extinction ratio measurement EN 61280-2-2 - ITU-T Recommendation G.959.1 2012 Optical transport network physical layer interfaces - - BS EN 61280-2-12:2014 2 IEC 61280-2-12:2014 IEC 2014 CONTENTS INTRODUCTION . 5 1 Scope 6 2 Normative references 6 3 Abbreviated terms . 6 4 Software sy
20、nchronization method and Q-factor 6 4.1 Example of asynchronous waveform and eye diagram reconstructed by software triggering technique 6 4.2 Q-factor formula 7 5 Apparatus 9 5.1 General . 9 5.2 Optical bandpass filter 10 5.3 High frequency receiver 10 5.4 Clock oscillator . 11 5.5 Electric pulse ge
21、nerator 11 5.6 Sampling module 11 5.7 Electric signal processing circuit . 12 5.8 Optical clock pulse generator 12 5.9 Optical sampling module . 12 5.10 Optical signal processing circuit 12 5.11 Synchronization bandwidth . 12 5.12 Monitoring system parameters 13 6 Procedure 13 6.1 General . 13 6.2 M
22、easuring eye diagrams and Q calculations . 13 Annex A (informative) Example of the signal processing required to reconstruct the synchronous eye diagram . 15 Annex B (informative) Adequate sampling time width (gate width) 17 Bibliography 18 Figure 1 Asynchronous waveform and synchronous eye diagram
23、of 40 Gbps RZ-signal reconstructed by software triggering technique . 7 Figure 2 RZ synchronous eye diagram reconstructed by software triggering technique, time window, and histogram . 8 Figure 3 Example of relationship between Q-factor and window width 8 Figure 4 Test system 1 for measuring eye dia
24、grams and Q-factor using the software triggering technique 9 Figure 5 Test system 2 for measuring eye diagrams and Q-factor using the software triggering technique 10 Figure A.1 Block diagram of the software triggering module . 15 Figure A.2 Example of interpolating a discrete spectrum and determini
25、ng beat frequency 16 Figure B.1 The typical calculated relationship between the adequate sampling time width (gate width) and the bit rate of the optical signal 17 Table 1 Monitoring system parameters . 13 BS EN 61280-2-12:2014IEC 61280-2-12:2014 IEC 2014 5 INTRODUCTION Signal quality monitoring is
26、important for operation and maintenance of optical transport networks (OTN). From the network operators point of view, monitoring techniques are required to establish connections, protection, restoration, and/or service level agreements. In order to establish these functions, the monitoring techniqu
27、es used should satisfy some general requirements: in-service (non-intrusive) measurement signal deterioration detection (both SNR degradation and waveform distortion) fault isolation (localize impaired sections or nodes) transparency and scalability (irrespective of the signal bit rate and signal fo
28、rmats) simplicity (small size and low cost). There are several approaches, both analogue and digital techniques, which make it possible to detect various impairments: bit error rate (BER) estimation 1,21 error block detection optical power measurement optical SNR evaluation with spectrum measurement
29、 3,4 pilot tone detection 5,6 Q-factor monitoring 7 pseudo BER estimation using two decision circuits 8,9 histogram evaluation with synchronous eye diagram measurement 10. A fundamental performance monitoring parameter of any digital transmission system is its end-to-end BER. However, the BER can be
30、 correctly evaluated only with out of service BER measurements, using a known test bit pattern in place of the real signal. On the other hand, in-service measurement can only provide rough estimates through the measurement of digital parameters (e.g., BER estimation, error block detection, and error
31、 count in forward error correction) or analogue parameters (e.g., optical SNR and Q-factor). An in-service optical Q-factor monitoring can be used for accurate quality assessment of transmitted signals on wavelength division multiplexed (WDM) networks. Chromatic dispersion (CD) compensation is requi
32、red for Q monitoring at measurement point in CD uncompensated optical link. However, conventional Q monitoring method is not suitable for signal evaluation of transmission signals, because it requires timing extraction by complex equipment that is specific to each BER and each format. The software t
33、riggering technique 11-14 reconstructs synchronous eye-diagram waveforms without an external clock signal synchronized to optical transmission signal from digital data obtained through asynchronous sampling. It does not rely on an optical signals transmission rate and data formats (RZ or NRZ). Measu
34、ring method of eye diagrams and Q-factor using the software triggering technique is a cost-effective alternative to BER estimations. With eye diagrams and Q-factor using software triggering test method, signal quality degradations due to optical signal-to-noise ratio (OSNR) degradation, to jitter fl
35、uctuations and to waveform distortion can be monitored. This is one of the promising performance-monitoring approaches for intensity modulated direct detection (IM-DD) optical transmission systems. 1Numbers in square brackets refer to the Bibliography. BS EN 61280-2-12:2014 6 IEC 61280-2-12:2014 IEC
36、 2014 FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES Part 2-12: Digital systems Measuring eye diagrams and Q-factor using a software triggering technique for transmission signal quality assessment 1 Scope This part of IEC 61280 defines the procedure for measuring eye diagrams and Q-factor of op
37、tical transmission (RZ and NRZ) signals using software triggering technique as shown in 4.1 14. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited app
38、lies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 61280-2-2, Fibre optic communication subsystem basic test procedures Part 2-2: Test procedure for digital systems Optical eye pattern, waveform, and extinction ratio measurement ITU-T
39、Recommendation G.959.1: 2012, Optical transport network physical layer interfaces 3 Abbreviated terms ASE amplified spontaneous emission BER bit error rate CD chromatic dispersion EDFA Er-doped fibre amplifier IM-DD intensity modulated direct detection RZ return-to-zero NRZ non-return-to-zero OBPF o
40、ptical bandpass filter OSNR optical signal-to-noise ratio OTN optical transport networks PMD polarization mode dispersion SNR signal-to-noise ratio WDM wavelength division multiplexing 4 Software synchronization method and Q-factor 4.1 Example of asynchronous waveform and eye diagram reconstructed b
41、y software triggering technique Figure 1 shows an example of a 40 Gb/s RZ-synchronous eye diagram constructed from asynchronous sampled data using the software triggering technique. The inset in Figure 1 shows an asynchronous waveform obtained from the same asynchronous sampled data. BS EN 61280-2-1
42、2:2014IEC 61280-2-12:2014 IEC 2014 7 Figure 1 Asynchronous waveform and synchronous eye diagram of 40 Gbps RZ-signal reconstructed by software triggering technique 4.2 Q-factor formula As shown in Figure 2, the Q-factor can be calculated from a histogram of “mark” (“1”) and “space” (“0”) levels in t
43、he time window, in which an appropriate time window is established in a large part of the eye opening. The time window is separated into “mark” (“1”) and “space” (“0”) levels, the average 0and standard deviation 0of the “space” (“0”) level data and the average 1and standard deviation 1 of the “mark”
44、 (“1”) level data are calculated, and the Q-factor is calculated by substituting the obtained 0, 0, 1, and 1into Formula (1). The Q-factor depends on the position of the centre of the time window. For optical transmission signal quality evaluation, the maximum value obtained by calculating Formula (
45、1) while changing the position of centre of the time window is defined as the Q-factor. 0101+=Q(1)The Q-factor also depends on width of the time window. Assuming that the signal waveform is sinusoidal RZ with duty ratio of 50 % (Figure 3(a) or sinusoidal NRZ (Figure 3(b) and 0= 1, calculated relatio
46、nships between Q-factor and window width are shown in Figure 3(c). A suitable window width is 0,1 UI or less for an RZ signal and 0,2 UI or less for an NRZ signal. IEC 1198/14 Eye diagram reconstructed by the software triggering technique Asynchronous waveform Sampling frequency: 40,379 MHz (asynchr
47、onous) Sampled data 4 3 2 1 0 1 Amplitude (arb.unit)10 5 0 15 20 25 Time (ps) BS EN 61280-2-12:2014 8 IEC 61280-2-12:2014 IEC 2014 Figure 2 RZ synchronous eye diagram reconstructed by software triggering technique, time window, and histogram Figure 3a Sinusoidal RZ with duty 50 % Figure 3b Sinusoida
48、l NRZ Figure 3c Calculated relationships between Q-factor and window width Figure 3 Example of relationship between Q-factor and window width IEC 1202/14 Qfactor(dB)RZ NRZ20 18 16 14 12 10 0 0,1 0,2 0,3 0,4 0,5 Window width IEC 1201/14 NRZ Amplitude (a.u.)1 0,5 0 0 0,20,5 0,71 Time (UI) IEC 1200/14
49、RZ Amplitude (a.u.)1 0,5 0 0 0,20,5 0,71 Time (UI) IEC 1199/14 Space 00Histogram 1Amplitude (a.u.)Time Mark Time window 16 5 4 3 2 1 0 1 BS EN 61280-2-12:2014IEC 61280-2-12:2014 IEC 2014 9 5 Apparatus 5.1 General Test systems are mainly composed of an optical bandpass filter, a high frequency receiver, a clock oscillator, an electric pulse generator, a sampling module, an electric signal processin
