1、PUBLISHED DOCUMENTPD CLC/TR 50460:2005Cable networks for television signals, sound signals and interactive services System guidelines for analogue optical transmission systemsICS 33.060.40g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51
2、g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58PD CLC/TR 50460:2005This Published Document was published under the authority of the Standards Policy and Strategy Committee on 14 November 2005 BSI 14 November 2005ISBN 0 580 46605 1National forewordThis Publish
3、ed Document is the official English language version of CLC/TR 50460:2005.The UK participation in its preparation was entrusted to Technical Committee EPL/100, Audio, video and multimedia systems and equipment, which has the responsibility to: A list of organizations represented on this committee ca
4、n be obtained on request to its secretary.NOTE On receipt of the ratified text of CLC/TR 50460:2005 from CENELEC it was noted that some of the figures and tables were incorrectly numbered. These typographical errors have been corrected in PD CLC/TR 50460:2005 and CENELEC TC 209 has been notified of
5、the errors.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Ca
6、talogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the in
7、terpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover, an inside front cover, the CLC/TR title page, pages 2 to 40, an inside back cover and a
8、back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsTECHNICAL REPORT CLC/TR 50460 RAPPORT TECHNIQUE TECHNISCHER BERICHT August 2005 CENELEC European Committee for Electrotechnical Standard
9、ization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. CLC/TR 50460:200
10、5 E ICS 33.060.40 English version Cable networks for television signals, sound signals and interactive services System guidelines for analogue optical transmission systems Rseaux de distribution par cbles pour signaux de tlvision, signaux de radiodiffusion sonore et services interactifs Lignes direc
11、trices pour les systmes de transmission optique analogiques Kabelnetze fr Fernsehsignale, Tonsignale und interaktive Dienste System-Leitfaden fr analoge optische bertragungssysteme This Technical Report was approved by CENELEC on 2005-05-21. CENELEC members are the national electrotechnical committe
12、es of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. CLC/TR 50460:2005 2 Fo
13、reword Standards are very important sources of information on terms, definitions and minimum requirements for technical products. EN 60728-6 is such a standard for optical equipment used in cable networks for television signals, sound signals and interactive services. However, a lot of additional in
14、formation and knowledge is needed for designing and planning complete optical transmission systems. This kind of information is not suitable for a standard because system engineers need freedom in their methods of finding economical solutions for special needs. CENELEC TC 209 therefore decided to de
15、velop this Technical Report which provides guidelines in how to use EN 60728-6 for planning analogue optical transmission systems. This Technical Report was prepared by the Technical Committee CENELEC TC 209, Cable networks for television signals, sound signals and interactive services. The text of
16、the draft was submitted to the formal vote and was approved by CENELEC as CLC/TR 50460 on 2005-05-21. 3 CLC/TR 50460:2005 Contents 1 Scope 5 1.1 General5 1.2 Scope of this Technical Report .5 2 Normative references 5 3 Terms, definitions, symbols and abbreviations .6 3.1 Symbols.6 3.2 Abbreviations
17、6 4 Topologies used for optical transmission systems in cable networks.6 4.1 Point to point system.7 4.2 Point to multi-point system7 4.3 Multi-point to point system 7 4.4 Real wavelength division multiplex system.8 4.5 Combinations 8 5 Influences of equipment and fibre parameters on the system perf
18、ormance.8 6 Optical modulation index.9 6.1 Single wavelength system 10 6.2 WDM systems 11 6.3 Choosing the right input level at the transmitter 11 7 Carrier to noise ratio. 12 7.1 Short haul links with a single transmitter 12 7.2 Long haul point to point link .13 7.2.1 Long haul links with DFB laser
19、s. 13 7.2.2 Long haul links with externally modulated transmitters . 13 7.3 Multiple transmitter systems (WDM) 14 7.4 Transmission systems with optical fibre amplifier 14 8 Linearity 15 8.1 Composite Second Order (CSO) . 15 8.1.1 CSO of 1 310 nm systems. 16 8.1.2 CSO of 1 550 nm systems. 17 8.2 Comp
20、osite Triple Beat (CTB). 17 9 Flatness 18 10 Output level 19 Annex A (informative) Brillouin scattering in optical fibres .20 Annex B (informative) Noise sources of optical transmission systems 22 B.1 Intensity noise 22 B.2 Shot noise of the receiver 25 B.3 Thermal noise 25 B.4 Carrier to noise rati
21、o. 25 CLC/TR 50460:2005 4 Annex C (informative) Non-linear distortion in optical transmission systems 26 C.1 Non-linear products definition 26 C.2 Non-linear products weighting . 27 C.3 Distortion generators in direct modulation cable network transmissions. 28 C.4 Third order modelling . 37 C.5 “Sum
22、mation“ of distortion products 38 Bibliography. 40 Figure 1 - Point to point (PTP) system .7 Figure 2 - Point to multi-point (PMP) system7 Figure 3 - Multipoint-to-point (WDM) system7 Figure 4 - Real WDM system .8 Figure 5 - Definition of OMI for an optical transmitter 10 Figure C.1 - (a) second and
23、 (b) third order distortion of Volterra series expansion.27 Figure C.2 - Weighted second and third order distortions repartition for the 42 carriers frequency allocation map defined in EN 50083-3 (software window capture)28 Figure C.3 - Polarisation-mode dispersion in single-mode fibre 29 Figure C.4
24、 - static curve of a laser showing the clipping effect30 Figure C.5 - Transmitted and backscattered power in the range of the Brillouin threshold .31 Figure C.6 - Cause of self phase modulation.32 Figure C.7 - CSO caused by laser chirping and chromatic dispersion 33 Figure C.8 - CSO degradation with
25、out PDL .34 Figure C.9 - CSO degradation with PDL = 0,5 dB 12.34 Figure C.10 - Simulated and measured intermodulation due to laser clipping 35 Figure C.11 - Zoom on a CTB 39 Table 1 - Interdependencies between equipment and system properties and the performance parameters 9 Table C.1 - Weightings of
26、 HD2, HD3, IMD2 and IMD327 5 CLC/TR 50460:2005 1 Scope 1.1 General Standards of the EN 50083 and EN 60728 series deal with cable networks for television signals, sound signals and interactive services including equipment, systems and installations - for headend-reception, processing and distribution
27、 of sound and television signals and their associated data signals and - for processing, interfacing and transmitting all kinds of signals for interactive services using all applicable transmission media. All kinds of networks like - CATV-networks - MATV- and SMATV-networks - individual receiving ne
28、tworks and all kinds of equipment, systems and installations installed in such networks, are within this scope. The extent of this standardisation work is from the antennas, special signal source inputs to the headend or other interface points to the network up to the terminal input. The standardisa
29、tion of any user terminals (i.e. tuners, receivers, decoders, multimedia terminals etc.) as well as of any coaxial and optical cables and accessories thereof is excluded. 1.2 Scope of this Technical Report This Technical Report provides guidelines and procedures for determining the overall performan
30、ce of optical transmissions systems used in cable networks for television signals, sound signals and interactive services. It is based on the requirements for optical equipment defined in the standard EN 60728-6 (Cable networks for television signals, sound signals and interactive services Part 6: O
31、ptical equipment) and should be used together with this standard. The information provided is meant to help field engineers and network planners (system designers) in planning and designing optical systems. Though this content is less dense than in a standard, basic knowledge about system parameters
32、 of cable networks is needed. 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) appli
33、es. EN 50083-3 2002 Cable networks for television signals, sound signals and interactive services - Part 3: Active wideband equipment for coaxial cable networks EN 50083-7 + A1 1996 2000 Cable networks for television signals, sound signals and interactive services - Part 7, System performance EN 607
34、28-6 2003 Cable networks for television signals, sound signals and interactive services - Part 6, Optical equipment (IEC 60728-6:2003) EN 60793-2 2004 Optical fibres - Part 2: Product specifications - General (IEC 60793-2:2003) IEC/TR 61931 1998 Fibre optics Terminology CLC/TR 50460:2005 6 3 Terms,
35、definitions, symbols and abbreviations For the purposes of this technical report, the terms, definitions, symbols and abbreviations given in EN 50083-7, EN 60728-6 and IEC/TR 61931 apply. 3.1 Symbols Additionally to the symbols given in the above mentioned references, the following graphical symbol
36、is used in the figures of this technical report: WDMwavelength division multiplexer 3.2 Abbreviations Additionally to the abbreviations given in the above mentioned references, the following abbreviations are used in this technical report: 2HD second harmonic distortion 3HD third harmonic distortion
37、 DFB distributed feedback DWDM Dense wavelength division multiplex IIN induced intensity noise IMD2 second order intermodulation IMD3 third order intermodulation IM-DD intensity modulation direct detection Irequivalent input noise current density of an optical receiver OMI optical modulation index M
38、PI multi-path interference PMD polarisation mode dispersion PMP point to mulit-point PTP point to point RMS root mean square SBS stimulated Brillouin scattering WDM wavelength division multiplexer 4 Topologies used for optical transmission systems in cable networks The overall performance of optical
39、 transmission systems depends on many parameters and conditions. Separating the applications into different categories simplifies the step by step analysis and leads to a better overview. A logical way to build up these categories is to distinguish different network topologies because it can be assu
40、med that the network architecture is always known in advance. Starting from this point of view the following five topologies can be identified as relevant for the user. 7 CLC/TR 50460:2005 4.1 Point to point system Point-to-point (PTP) systems consist of a single optical transmitter and a single opt
41、ical receiver connected by a single line of fibre (Figure 1). EO EOFigure 1- Point to point (PTP) system This configuration can typically be found in trunk lines feeding areas cabled with coax (HFC networks). Both wavelengths, 1 310 nm and 1 550 nm, are used for these systems. Most of the optical bu
42、dget is consumed by the fibres attenuation (long distance system). At 1 550 nm, optical amplifiers can be used to extend the range of this kind of system. 4.2 Point to multi-point system In point to multi-point (PMP) systems a single optical transmitter feeds more than one optical receiver. The rece
43、ivers are connected to a main fibre via optical couplers and tap fibres as shown in Figure 2. EOEOEOEOFigure 2 - Point to multi-point (PMP) system An alternative configuration for feeding more than one receiver from a single transmitter is to use an optical splitter at the transmitter node and indiv
44、idual fibres from the transmitter node to each receiver. This leads to a star topology which should be treated as multiple PTP systems with a single transmitter. PMP systems are typically used when different coaxial parts of a network shall be supplied with the same signal saving as much fibre as po
45、ssible (optical distribution systems). Depending on the fibre lengths, both wavelengths are used. At 1 550 nm, optical amplifiers can be used to compensate for the fibre and splitting losses. 4.3 Multi-point to point system Multi-point-to-point systems consist of at least two transmitters with diffe
46、rent wavelengths sending their signals to a common receiver. The transmitter signals may be combined by an optical coupler or if the link loss is critical, by a wavelength multiplexer (Figure 3). WDMEOEOEOFigure 3 - Multipoint-to-point (WDM) system CLC/TR 50460:2005 8 Since optical receivers usually
47、 have a very broad input wavelength range, the central wavelengths of the transmitters may be extremely different (e.g. 1 310 nm and 1 550 nm). In order to avoid signal mixing in the receiver the optical spectrums of the transmitters have to differ at least by the upper limit of the receivers electr
48、ical frequency range. If only signals in the 1 550 nm wavelength range are used, optical amplifiers can be employed for extending the fibre length. Since all input signals of the system are provided at the same system output, different frequency ranges have to be used for modulating the transmitters
49、. This kind of topology is typically chosen if part of a network shall be provided with signals from different locations. 4.4 Real wavelength division multiplex system Real wavelength division multiplex systems consist of at least two PTP systems operating on the same fibre. The transmitter signals are combined at the transmitter node with a wavelength multiplexer or if the link loss is not critical, by an optical coupler. At the receiver node the different signals are separated by another wavelength multiplexer and led to individual
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