1、 International Telecommunication Union ITU-T J.186TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2008) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Digital transmission of television signals Transmission equipment for multi-channel televi
2、sion signals over optical access networks by sub-carrier multiplexing (SCM) Recommendation ITU-T J.186 Rec. ITU-T J.186 (06/2008) i Recommendation ITU-T J.186 Transmission equipment for multi-channel television signals over optical access networks by sub-carrier multiplexing (SCM) Summary Recommenda
3、tion ITU-T J.186 describes a transmission method for multi-channel television signals over optical access networks. J.186 transmission equipment is capable of transmitting multi-channelAM-VSB, and digital video signals by using sub-carrier multiplexing (SCM). Source Recommendation ITU-T J.186 was ap
4、proved on 13 June 2008 by ITU-T Study Group 9 (2005-2008) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T J.186 (06/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication techno
5、logies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecom
6、munication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some area
7、s of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized oper
8、ating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“
9、 or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the pract
10、ice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation develop
11、ment process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefor
12、e strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.186 (06/2008) iii CONTENTS Page 1 Scope 1 2 References.
13、 1 2.1 Normative References 1 2.2 Informative References 2 3 Abbreviations and acronyms 2 3.1 Symbols 4 3.2 Conventions 4 4 System description 4 5 Performance of analogue and/or digital video transmission system 5 5.1 Specified transmission quality for analogue video signal 5 5.2 Specified transmiss
14、ion quality for digital video signal 5 Annex A Optical Systems for Broadcast Signal Transmission: system A . 7 A.1 System description 7 A.2 Transmitter (TX) 9 A.3 AMP/BRC 11 A.4 Optical network terminal for video signals (V-ONT) 12 Annex B SCM transmission equipment: system B. 14 B.1 System descript
15、ion 14 B.2 Transmitter (TX) 16 B.3 Amplifier and branch unit (AMP/BRC) . 17 B.4 Optical network terminal for video signals (V-ONT) 19 Appendix I Modulation index and minimum received optical power 21 iv Rec. ITU-T J.186 (06/2008) Introduction For an undetermined period before digital transmission fu
16、lly replaces analogue transmission, it will be necessary for optical access networks to carry both formats. Digital signals should be transmitted using Frequency-Division Multiplexing (FDM) in addition to analogue signals in order to assure an effective transition from analogue to digital transmissi
17、on. Rec. ITU-T J.186 (06/2008) 1 Recommendation ITU-T J.186 Transmission equipment for multi-channel television signals over optical access networks by sub-carrier multiplexing (SCM) 1 Scope This Recommendation describes a method of transmitting multi-channel television signals over optical access n
18、etworks through the use of Sub-Carrier Multiplexing (SCM). In the SCM technique, the main carrier is the optical frequency signal carrier; the sub-carriers transfer the electrically multiplexed FDM video signals in the optical sideband. The format of the signals output by the Photo Detector (PD) of
19、the Optical Network Terminal (ONT) is the same as that of the signals input to the modulator of the optical transmitter. The SCM method is used in the trunk line of Hybrid Fibre-Coax (HFC) systems. The system described in this Recommendation transmits FDM analogue AM-VSB and digital video signals by
20、 SCM technology. The optical modulation format is Intensity Modulation (IM). Optical amplifiers are used to compensate the losses of the optical transmission/splitters used to create the access network. Dispersion compensation fibres (DCF) are used to compensate the chromatic dispersion of access ne
21、twork fibres. DCF imposes the reverse chromatic dispersion in advance in order to offset the degradation due to CSO created by the transmission of 1.55 m optical signals over 1.3 m zero-dispersion access fibres. SCM technology is simple, and is based on an electrical/optical (E/O) converter and opti
22、cal amplifiers in the transmitter side, and an optical/electrical (O/E) converter in the receiver side. However, the allowable optical transmission/splitter loss is smaller than that in the FM converted system. Moreover, optical reflections in the transmission lines may degrade video quality. This s
23、ystem can be integrated with the G.983 series B-PON system by using G.983.3 WDM technology, with the G.984 series G-PON system by using G.984.5 WDM technology, and with the IEEE 802.3ah EPON systems. This allows the PON system to offer broadcast services and also data and voice communication service
24、s over the same optical access network. By using the bidirectional data PON system, upstream signals, e.g., control functionality and data to indicate user requirements, can be transmitted as well. NOTE The structure and content of this Recommendation have been organized for ease of use by those fam
25、iliar with the original source material; as such, the usual style of ITU-T recommendations has not been applied. 2 References 2.1 Normative References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Reco
26、mmendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other refer
27、ences listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 2 Rec. ITU-T J.186 (06/2008) 1 Recommendation ITU-T J.83 (2007), Digital
28、 multi-programme systems for television, sound and data services for cable distribution. 2 Recommendation ITU-T J.87 (2001), Use of hybrid cable television links for the secondary distribution of television into the users premises. 3 ANSI/SCTE 85-1 (2003), HMS HE Optics Management Information Base (
29、MIB) Part 1: SCTE-HMS-HE-OPTICAL TRANSMITTER MIB. 4 ANSI/SCTE 85-2 (2003), HMS HE Optics Management Information Base (MIB) Part 2: SCTE-HMS-HE-OPTICAL RECEIVER-MIB. 5 ANSI/SCTE 85-3 (2004), HMS HE Inside Plant Management Information Base (MIB) SCTE-HMS-HE-OPTICAL-AMPLIFIER-MIB. 6 Recommendation ITU-
30、T G.984.4 (2008), Gigabit-capable Passive Optical Networks (G-PON): ONT management and control interface specification. 7 Recommendation ITU-R BT.1306-3 (2006), Error-correction, data framing, modulation and emission methods for digital terrestrial television broadcasting. 8 Recommendation ITU-R BO.
31、1408-1 (2002), Transmission system for advanced multimedia services provided by integrated services digital broadcasting in a broadcasting-satellite channel. 9 IEC 60728-1 (2007), Cable networks for television signals, sound signals and interactive services-Part 1; System performance of forward path
32、s. 2.2 Informative References Recommendation ITU-T G.983.1 (2005), Broadband optical access systems based on Passive Optical Networks (PON). Recommendation ITU-T G.983.3 (2001), A broadband optical access system with increased service capability by wavelength allocation; Amendment 2 (2005). Recommen
33、dation ITU-T G.984.1 (2008), Gigabit-capable Passive Optical Networks (GPON): General characteristics. Recommendation ITU-T G.984.2 (2003), Gigabit-capable Passive Optical Networks (GPON): Physical Media Dependent (PMD) layer specification; Amendment 1 (2006). Recommendation ITU-T G.984.3 (2008), Gi
34、gabit-capable Passive Optical Networks (GPON): Transmission convergence layer specification. Recommendation ITU-T G.984.5 (2007), Gigabit-capable Passive Optical Networks (GPON): Enhancement band. IEEE Standard 802.3 (2005), Information technology Telecommunications and Information Exchange Between
35、Systems Local and metropolitan area networks Specific Requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications. 3 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AGC Automatic G
36、ain Controller ALC Automatic Level Controller AM-VSB Amplitude Modulation Vestigial Sideband Rec. ITU-T J.186 (06/2008) 3 AMP/BRC-U Amplifier and Branch Unit A-RA Receiver Amplifier for Analogue video transmission A-TA Transmitter Amplifier for Analogue video transmission CNR Carrier-to-Noise Ratio
37、CSO Composite Second Order distortion CTB Composite Triple Beat distortion D/U Desired-to-Undesired distortion ratio DCF Dispersion Compensation Fibre DI Discrete Interference D-RA Receiver Amplifier for Digital video transmission D-TA Transmitter Amplifier for Digital video transmission E/O Electri
38、cal to Optical FDM Frequency-Division Multiplexing HE Head End HFC Hybrid Fibre Coax IM Intensity Modulation ISDB-T Integrated Services Digital Broadcasting for Terrestrial LE Line Extender O/E Optical to Electrical ONT Optical Network Terminal PD Photo Detector QAM Quadrature Amplitude Modulation Q
39、PSK Quadrature Phase-Shift Keying RA Receiver Amplifier RIN Relative Intensity Noise SCM Sub-Carrier MultiplexingSNMP Simple Network Management Protocol STB Set-Top Box TA Transmitter Amplifier TC8PSK Trellis Coded 8-Phase Shift Keying TX Transmitter V-OLT Optical Line Terminal for Video signals V-O
40、NT Optical Network Terminal for Video signals VSWR Voltage Standing Wave Ratio WDM Wavelength-Division Multiplexing XM Cross Modulation distortion 4 Rec. ITU-T J.186 (06/2008) 3.1 Symbols This Recommendation uses the following symbols: N Total number of FDM carriers mjIntensity modulation index of t
41、he jth carrier 3.2 Conventions If this Recommendation is implemented, the key words “MUST“ and “SHALL“ as well as “REQUIRED“ are to be interpreted as indicating a mandatory aspect of this Recommendation. The keywords indicating a certain level of significance of particular requirements which are use
42、d throughout this Recommendation are summarized below. “MUST“ This word or the adjective “REQUIRED“ means that the item is an absolute requirement of this Recommendation. “MUST NOT“ This phrase means that the item is an absolute prohibition of this Recommendation. “SHOULD“ This word or the adjective
43、 “RECOMMENDED“ means that there may be valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course. “SHOULD NOT“ This phrase means that there may exist valid reasons in particular circ
44、umstances when the listed behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label. “MAY“ This word or the adjective “OPTIONAL“ means that this item is truly optional. One vendor ma
45、y choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item. 4 System description Figure 1 System description of the SCM multi-channel video signal transmission system Figure 1 is a system descriptio
46、n of multi-channel television signals transmission using Sub-Carrier Multiplexing (SCM). To minimize the deterioration in video signal quality, this system was optimized in two steps: trunk line transmission and access network transmission. The trunk line transmission system consists of digitally en
47、coded signals transmission or analogue signal transmission. In the second step, all video signals (both analogue and digital modulation formats) are mixed in the V-OLT, and then transmitted from the V-OLT to the V-ONT across the access network. Rec. ITU-T J.186 (06/2008) 5 5 Performance of analogue
48、and/or digital video transmission system 5.1 Specified transmission quality for analogue video signal Table 1 shows specified transmission quality for the AM-VSB analogue video signal. The carrier power of the analogue video signal is measured as the peak envelope power. Table 1 Specified transmissi
49、on quality for analogue video signal M-system NTSC TV system North America Other regions B, G-system PAL L-system SECAM Noise bandwidth 4.0 MHz 4.0 MHz 4.75 MHz 5.0 MHz CNR 46 dB (Note 1) 43 dB (Note 2) 44 dB 44 dB CSO 53 dB 53 dB 52 dB 52 dB CTB 53 dB (Note 1) 54 dB (Note 2) 52 dB 52 dB XM 46 dB 46 dB 46 dB 46 dB DI 60 dB (Note 1) 57 dB (Note 2) Not specified Not specified NOTE 1 North America commonly used value. NOTE 2 Refer to 9. 5.2 Specified transmission quality for digital
