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1、 - - - - - - P - - - - - c - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - TECHNICAL REPORT CLC/TR 50083-10-1 RAPPORT TECHNIQUE TECHNISCHER BERICHT February 2009 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Ko
2、mitee fr Elektrotechnische 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. CLC/TR 50083-10-1:2009 E ICS 33.060.40 English version Cable networks for television sig
3、nals, sound signals and interactive services - Part 10-1: Guidelines for the implementation of return paths in cable networks Rseaux de distribution par cbles pour signaux de tlvision, signaux de radiodiffusion sonore et services interactifs - Partie 10-1: Lignes directrices relatives la mise en oeu
4、vre de la voie de retour dans les rseaux cbls Kabelnetze fr Fernsehsignale, Tonsignale und interaktive Dienste - Teil 10-1: Leitfaden fr die Einrichtung von Rckkanlen in Kabelnetzen This Technical Report was approved by CENELEC on 2008-12-05. CENELEC members are the national electrotechnical committ
5、ees of Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United
6、 Kingdom. PD CLC/TR 50083-10-1:2009 CLC/TR 50083-10-1:2009 - 2 - Foreword 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 the draft was submitted to the vote in accordance with th
7、e Internal Regulations, Part 2, Subclause 11.4.3.3 (simple majority) and was approved by CENELEC as CLC/TR 50083-10-1 on 2008-12-05. _ PD CLC/TR 50083-10-1:2009 - 3 - CLC/TR 50083-10-1:2009 Contents 1 Scope . 7 1.1 General 7 1.2 Specific scope of this Technical Report 7 2 Normative references . 7 3
8、Terms, definitions, symbols and abbreviations 8 3.1 Terms and definitions 9 3.2 Symbols 11 3.3 Abbreviations 12 4 Network architecture 14 4.1 HFC architecture .14 4.2 Upgrade alternatives .16 4.3 Active or passive return path 26 4.4 In building network 26 4.5 In home network 27 5 Network design .28
9、5.1 Considerations 28 5.2 Return path loss, path loss difference and return path slope .28 5.3 Noise and nonlinearity, optimising signal levels .32 5.4 Isolation between outlets.35 5.5 Equalisation and filtering in return paths .35 6 Channel planning 38 6.1 Purpose of this section 38 6.2 Introductio
10、n .38 6.3 Summary .38 6.4 Considerations for channel planning .39 6.5 Common path distortion products .44 6.6 European upstream bandwidths .44 6.7 Channel width .44 6.8 QPSK/16QAM operation and channel widths .44 6.9 Available return path spectrum (Table 8) 45 6.10 Channel plans .46 6.11 Network rad
11、iation 48 7 Equipment for return path implementation 48 7.1 General48 7.2 Return path amplifiers .48 7.3 Equipment for fibre optic return links 51 8 Installation and maintenance 51 8.1 Signal level adjustment .51 8.2 Monitoring and measurements .56 PD CLC/TR 50083-10-1:2009 CLC/TR 50083-10-1:2009 -
12、4 - Annex A (informative) Interference on return path 59 A.1 Multiple interference 59 A.2 Impulse interference 69 A.3 Interference from home terminals .71 A.4 Hum modulation 71 A.5 Common path distortion (CPD) .72 Annex B (informative) Methods of measurement 82 B.1 Noise power ratio (NPR) measuremen
13、t on return path 82 B.2 10-Tone measurement 88 B.3 Modulation error ratio (MER) measurement on return path 91 B.4 Null packet and PRBS definitions .93 Annex C (informative) ITU DWDM grid 95 Bibliography 97 Figures Figure 1 Typical HFC topology . 14 Figure 2 Regional network . 15 Figure 3 Trunk-and-d
14、istribution architecture using only coaxial equipment . 16 Figure 4 HFC system 17 Figure 5 Generic diagram showing the mapping of nodes and CMTS(s) to segments . 18 Figure 6 Segment comprising a single CMTS to six optical nodes 18 Figure 7 Spectrum allocation bandwidth 19 Figure 8 Basic node archite
15、cture 20 Figure 9 Re-arranged feeds (two CMTS serving four nodes) 21 Figure 10 Optical node with frequency stacking 22 Figure 11 Divided node 22 Figure 12 Return path segmentation 23 Figure 13 Division of the node areas using additional fibres. . 23 Figure 14 DWDM (CWDM) return path transmission . 2
16、4 Figure 15 Digital return technology basic concept . 25 Figure 16 Two return paths multiplexed to the transmission stream . 25 Figure 17 Optical node segmentation 26 Figure 18 In house structures for transparent return path transmission 27 Figure 19 Example of forward and return path network with o
17、perating levels for the drop and in home parts of the network . 29 Figure 20 Example of a block diagram of return path amplifier 49 Figure 21 Commissioning of the forward path 52 Figure 22 Commissioning of the return path amplifiers using the same method as on the forward path 52 Figure 23 Problem w
18、hen commissioning return path amplifiers following the method used for downstream amplifiers (standard output levels) . 53 Figure 24 Unity gain method 54 Figure 25 Optical reverse path . 54 PD CLC/TR 50083-10-1:2009 - 5 - CLC/TR 50083-10-1:2009 Figure 26 Optical node with reverse transmitter 55 Figu
19、res in annexes Figure A.1 Typical spectrum of a return path . 59 Figure A.2 Noise funnelling 60 Figure A.3 Average noise level vs. the number of subscribers and the return path frequency 6 . 61 Figure A.4 Simplified equivalent circuit of a drop cable . 61 Figure A.5 Screening effectiveness of a coax
20、ial cable vs. frequency 63 Figure A.6 Spectrogram of noise level vs. frequency and time (example) . 65 Figure A.7 Maximum, minimum and average noise levels vs. frequency (example) . 66 Figure A.8 Centile analysis of noise levels vs. frequency (example) . 67 Figure A.9 Temporal evolution of the -10 d
21、B(mV) threshold crossing occurrence (example) . 68 Figure A.10 Frequency evolution of the -10 dB(mV) threshold crossing occurrence (example) . 68 Figure A.11 Illustration of impulse noise measurement according to the method described in EN 60728-10 . 70 Figure A.12 Example for the use of the return
22、path frequency range 72 Figure A.13 Test set-up for CPD simulation . 74 Figure A.14 Intermodulation products with 8 MHz spacing 75 Figure A.15 Contact resistance as function of contact pressure 76 Figure A.16 Upstream pass-band characterisation 77 Figure A.17 Set-up of test signals 78 Figure A.18 Te
23、st set-up for passive devices 78 Figure A.19 Test set-up for power passing devices . 79 Figure A.20 Thermal cycle profile . 79 Figure A.21 Spectral response with CPD in the return path 80 Figure B.1 Band-pass and band-stop filters response . 82 Figure B.2 NPR test set up . 83 Figure B.3 NPR versus R
24、F power density applied at input of optical transmitter and determination of OMI 100 % 84 Figure B.4 Example of the frequency response of the optional band-pass filter 85 Figure B.5 Correction factor versus level difference 86 Figure B.6 Example of NPR dynamic range. 88 Figure B.7 Dynamic Range (dB)
25、 plotted versus NPR (dB) 88 Figure B.8 Alternative NPR measurement principle . 89 Figure B.9 Relationship between classical NPR method and multi-tone method 90 Figure B.10 Test set-up for Modulation Error Ratio (MER) measurement . 91 Figure B.11 Example of constellation diagram for a 64QAM modulatio
26、n format . 92 Tables Table 1 Summary of in home return path losses . 31 Table 2 Calculation of return path versus temperature 32 Table 3 Broadcasting allocations between 5 MHz and 42 MHz . 41 Table 4 Amateur and Citizens Band allocations between 5 MHz and 42 MHz 41 Table 5 DOCSIS/EuroDOCSIS symbol r
27、ates and channel widths . 42 Table 6 Data carriers in the gaps between broadcasting bands 43 PD CLC/TR 50083-10-1:2009 CLC/TR 50083-10-1:2009 - 6 - Table 7 Data carriers in the gaps between broadcasting, amateur and CB bands . 43 Table 8 Available spectrum between 5 MHz and 65 MHz . 45 Table 9 Examp
28、le of a 1,6 MHz wide channel plan (avoiding CPD products) . 46 Table 10 Example of a 3,2 MHz wide channel plan . 47 Table 11 Permitted radiation 0,3 MHz to 30 MHz (A-Deviation for Great Britain) 48 Table 12 Permitted radiation 30 MHz to 68 MHz (A-Deviation for Great Britain) 48 Table 13 Split freque
29、ncies used in Europe . 50 Table 14 Alarm thresholds for upstream monitoring (example) . 58 Tables in annexes Table A.1 European EMC standards applicable to home terminals 71 Table B.1 Band-stop filter notch frequencies . 82 Table B.2 Noise correction factor . 86 Table B.3 Null transport stream packe
30、t definition 93 Table C.1 ITU DWDM grid 95 PD CLC/TR 50083-10-1:2009 - 7 - CLC/TR 50083-10-1:2009 1 Scope 1.1 General Standards of the EN 50083 and EN 60728 series deal with cable networks including equipment and associated methods of measurement for headend reception, processing and distribution of
31、 television signals, sound signals and their associated data signals and for processing, interfacing and transmitting all kinds of signals for interactive services using all applicable transmission media. This includes CATV1)-networks; MATV-networks and SMATV-networks; individual receiving networks;
32、 and all kinds of equipment, systems and installations installed in such networks. The extent of this standardization work is from the antennas and/or special signal source inputs to the headend or other interface points to the network up to the terminal input. The standardization of any user termin
33、als (i.e., tuners, receivers, decoders, multimedia terminals, etc.) as well as of any coaxial, balanced and optical cables and accessories thereof is excluded. 1.2 Specific scope of this Technical Report This document is intended to provide guidance to network designers on the issues which should be
34、 addressed, when considering the design of a CATV (HFC) return path. Items such as return path architecture Telecommunication network equipment; Electromagnetic Compatibility (EMC) requirements ETSI ES 201 488-1 Access and Terminals (AT); Data Over Cable Systems; Part 1: General ETSI ES 201 488-2 Ac
35、cess and Terminals (AT); Data Over Cable Systems; Part 2: Radio Frequency Interface Specification ETSI ES 202 488-1 Access and Terminals (AT); Second Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 1: General ETSI ES 202 488-2 Access and Terminals (A
36、T); Second Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 2: Radio frequency interface specification ETSI ETS 300 800 Digital Video Broadcasting (DVB);Interaction channel for Cable TV distribution systems (CATV) IEC 60050 International Electrotechni
37、cal Vocabulary (IEV) IEC 60617 database Graphical symbols for diagrams IEC/TR 61931 Fibre optic - Terminology ISO/IEC 13818-1 Information technology - Generic coding of moving pictures and associated audio information: Systems PD CLC/TR 50083-10-1:2009 - 9 - CLC/TR 50083-10-1:2009 3 Terms, definitio
38、ns, symbols and abbreviations 3.1 Terms and definitions For the purposes of this technical report, the terms and definitions listed hereafter apply. As far as possible the available terms and definitions are taken from IEC 60050 series and are repeated below. The relevant IEV-numbers or other refere
39、nces are given in rectangular brackets after the definition text. 3.1.1 common path distortion intermodulation distortion of downstream signals, mainly due to nonlinearities found at metallic junctions. The distortions are manifest as a series of beats (caused by analogue downstream channels) or a b
40、and(s) of noise (caused by digital downstream channels) most noticeably in the upstream path. CPD may also be present in the downstream path, but since it adds with other downstream distortions (i.e. CTB and CSO), caused by active components, it is difficult to differentiate between the two. The non
41、linear behaviour found at passive junctions may be due to a number of reasons including corrosion, typically from exposure to the elements, dissimilar metals, contact pressure, and junctions involving connectors contaminated with carbonaceous materials 3.1.2 downstream direction direction of signal
42、flow in a cable network from the headend or any other central point (node) of a cable network towards the subscriber EN 60728-10, modified 3.1.3 forward path (downstream) physical part of a cable network by which signals are distributed in the downstream direction from the headend or any other centr
43、al point (node) of a cable network towards the subscriber EN 60728-10, modified 3.1.4 gateway functional unit that connects two computer networks with different network architectures EXAMPLES LAN gateway, mail gateway NOTE The computer networks may be either local area networks, wide area networks o
44、r other types of networks. IEV 732-01-16 3.1.5 headend assembly of equipment feeding signals into a cable network from local or external sources, including equipment for reception and signal processing IEV 723-09-11, modified NOTE The headend may, for example, comprise antenna amplifiers, frequency
45、converters, combiners, separators and generators. 3.1.6 hub local area distribution point for the insertion and recovery of two-way narrowcast signals such as DOCSIS/EuroDOCSIS with broadcast transmissions from the headend in the RF domain (frequency multiplexing) 3.1.7 hybrid fibre coaxial network
46、HFC network cable network which comprises optical equipment and cables and coaxial equipment and cables in different parts EN 60728-10 PD CLC/TR 50083-10-1:2009 CLC/TR 50083-10-1:2009 - 10 - 3.1.8 ingress noise noise which is caused by electromagnetic interference into cable networks. Its power decreases with increasing frequency. It is permanently