BRITISH STANDARD BS EN 60728 7 1 2005 Cable networks for television signals, sound signals and interactive services — Part 7 1 Hybrid Fibre Coax Outside Plant Status Monitoring — Physical (PHY) Layer[.]
BRITISH STANDARD BS EN EN 60728-7-1:2005 60728-7-1:2005 +A1:2015 Cable networks for television signals, sound signals and interactive services — Part 7-1: Hybrid Fibre Coax Outside Plant Status Monitoring — Physical (PHY) Layer Specification The European Standard EN 60728-7-1:2005 has the status of a British Standard ICS 35.100.10; 33.160.01; 33.040.01 BS EN 60728-7-1:2005+A1:2015 National foreword This British Standard is the UK implementation of EN 60728-7-1:2005+A1:2015 It is identical to IEC 60728-7-1:2003+A1:2015 It supersedes BS EN 60728-7-1:2005 which will be withdrawn on June 2018 The start and finish of text introduced or altered by amendment is indicated in the text by tags Tags indicating changes to IEC text carry the number of the IEC amendment For example, text altered by IEC amendment is indicated by The UK participation in its preparation was entrusted by Technical Committee EPL/100, Audio, video and multimedia systems and equipment, to Subcommittee EPL/100/4, Cable distribution equipment and systems A list of organizations represented on this subcommittee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 16 March 2005 © The British Standards Institution 2015 Published by BSI Standards Limited 2015 ISBN 978 580 79846 Amendments/corrigenda issued since publication Date Comments 31 July 2015 Implementation of IEC amendment 1:2015 with CENELEC endorsement A1:2015 EN60728-7-1:2005+A1 60728-7-1 EN EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM February June 2015 2005 ICS 35.100.10; 33.160; 33.040 English version Cable networks for television signals, sound signals and interactive services Part 7-1: Hybrid Fibre Coax Outside Plant Status Monitoring – Physical (PHY) Layer Specification (IEC 60728-7-1:2003) Réseaux de distribution par câbles pour signaux de télévision, signaux de radiodiffusion sonore et services interactifs Partie 7-1: Surveillance de l'état des installations extérieures des réseaux hybrides fibre optique et câble coaxial Spécification de la couche physique (CEI 60728-7-1:2003) Kabelnetze für Fernsehsignale, Tonsignale und interaktive Dienste Teil 7-1: Zustandsüberwachung HybridFaser-Koax-Netze (HFC) – Festlegung Bitübertragungsschicht (PHY) (IEC 60728-7-1:2003) This European Standard was approved by CENELEC on 2004-12-01 CENELEC 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 application to the Central Secretariat or to any CENELEC member This European Standard exists in one official version (English) A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions CENELEC members are the national electrotechnical committees 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 CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für 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 EN 60728-7-1:2005 E Page BS EN 60728-7-1:2005+A1:2015 EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 Foreword The text of the International Standard IEC 60728-7-1:2003, prepared by technical area 5: Cable networks for television signals, sound signals and interactive services, of IEC TC 100, Audio, video and multimedia systems and equipment, was submitted to the formal vote and was approved by CENELEC as EN 60728-7-1 on 2004-12-01 without any modification The following dates were fixed: – latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2005-12-01 – latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2007-12-01 Endorsement notice The text of the International Standard IEC 60728-7-1:2003 was approved by CENELEC as a European Standard without any modification EN 60728-7-1:2005/A1:2015 EuropeanEuropean foreword foreword to amendment A1 The text of document 100/2417/FDIS, future edition of IEC 60728-7-1:2003/A1, prepared by Technical Area “Cable networks for television signals, sound signals and interactive services” of IEC/TC 100 “Audio, video and multimedia systems and equipment" was submitted to the IECCENELEC parallel vote and approved by CENELEC as EN 60728-7-1:2005/A1:2015 The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2016-03-03 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2018-06-03 Attention is drawn to the possibility that 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 60728-7-1:2003/A1:2015 was approved by CENELEC as a European Standard without any modification BS EN 60728-7-1:2005+A1:2015 Page EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 CONTENTS INTRODUCTION Scope .5 Normative references .6 Terms, definitions and abbreviations 3.10 Abbreviated terms HMS reference architecture forward and return channel specifications .8 4.1 HMS specification documents 4.2 Functional assumptions Physical layer specification .9 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Separate forward and return channels .9 Single forward and return path channels 10 Byte-based transmission 10 Byte formats and transmission order 10 Packet-based transmission 10 Duplex operation 10 Forward and return channel specifications 10 Media access control layer interface 17 RF cut-off 17 Bibliography 18 Figure – HMS Reference architecture diagram .8 Figure – Bit transmission order 10 Table – Transponder type classifications .5 Table – HMS document family .8 (North America and Europe) Table – Spectral limits by geographical area Table – HMS PHY channel RF and modulation specifications 11 BS EN 60728-7-1:2005+A1:2015 EN 60728-7-1:2005+A1:2015 INTRODUCTION Standards and other deliverables of the IEC 60728 series deal with cable networks including equipment and associated methods of measurement for headend reception, processing and distribution of television and sound signals and for processing, interfacing and transmitting all kinds of data signals for interactive services using all applicable transmission media These signals are typically transmitted in networks by frequency-multiplexing techniques This includes for instance • regional and local broadband cable networks, • extended satellite and terrestrial television distribution systems, • individual satellite and terrestrial television receiving systems, and all kinds of equipment, systems and installations used in such cable networks, distribution and receiving systems 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 of the customer premises equipment The standardization work will consider coexistence with users of the RF spectrum in wired and wireless transmission systems The standardization 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 BS EN 60728-7-1:2005+A1:2015 Page EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 CABLE NETWORKS FOR TELEVISION SIGNALS, SOUND SIGNALS AND INTERACTIVE SERVICES – Part 7-1: Hybrid Fibre Coax Outside Plant status monitoring – Physical (PHY) layer specification Scope This part of IEC 60728 specifies requirements for The Hybrid Fibre Coax (HFC) Outside Plant (OSP) Physical (PHY) Layer Specification and is part of the series of specifications developed by the Hybrid Management Sub-Layer (HMS) subcommittee under the SCTE The purpose of the HMS specification is to support the design and implementation of interoperable management systems for evolving HFC cable networks The HMS Physical (PHY) Layer Specification describes the physical layer portion of the protocol stack used for communication between HMS-compliant transponders interfacing to managed outside plant network elements (NE) and a centralized head-end element (HE) This standard describes the PHY layer requirements that must be implemented by all Type and Type compliant OSP HMS transponders on the HFC plant and the controlling equipment in the head-end Any exceptions to compliance with this standard will be specifically noted herein as necessary Refer to Table for a full definition of the type classifications Electromagnetic Compatibility (EMC) is not specified in this standard and is left to the vendor to ensure compliance with local EMC regulatory requirements Other than operating temperature, physical parameters such as shock, vibration, humidity, etc., are also not specified and left to the vendor’s discretion Transponder type classifications referenced within the HMS series of standards are defined in Table Table – Transponder type classifications Type Description Type Refers to legacy transponder equipment, which is incapable of supporting the HMS specifications Type Refers to stand-alone transponder equipment (legacy or new) which can be upgraded to support the HMS specifications Type Refers to a stand-alone, HMScompliant transponder Application This transponder interfaces with legacy network equipment through proprietary means This transponder could be managed through the same management applications as the other types through proxies or other means at the head-end This transponder interfaces with legacy network equipment through proprietary means Type is a standards-compliant transponder (either manufactured to the standard or upgraded) that connects to legacy network equipment via a proprietary interface This transponder interfaces with network equipment designed to support the electrical and physical specifications defined in the HMS standards It can be factory or field-installed Its RF connection is independent of the monitored NE This transponder interfaces with network equipment designed to support the electrical specifications defined in the HMS standards Type Refers to a stand-alone or embedded, HMS-compliant transponder It may or may not support the physical specifications defined in the HMS standards It can be factory-installed It may or may not be field-installed Its RF connection is through the monitored NE Page BS EN 60728-7-1:2005+A1:2015 EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 Page Normative references EN 60728−7−1:2005 None Normative references Terms, definitions and abbreviations None For the purposes of this document, the following terms and definitions apply Terms, definitions and abbreviations 3.1 forward spectrum forward path band the pass-band of of frequencies in HFC cable systems with a lower ofofbetween continuous set of frequencies in HFC cable systems with a loweredge edge between 48 48 MHz For the purposes this document, the following terms and definitions apply 87,5MHz, MHz,depending dependingonon particular geographical and an edge upperthat edge that is and 87,5 thethe particular geographical area,area, and an upper is typically typically in the range ofMHz 300toMHz to MHz 860 MHz dependingononimplementation implementation in the range of 300 000 depending 3.1 forward spectrum Note to entry: Due to different channel spacing plans in use, this upper frequency limit may not be 3.2 the pass-band of but frequencies in HFC cable with a 006 lower edge between MHz exactly 000 MHz, some megahertz higher, e.g.systems 002 MHz or MHz The of notation 00048MHz in full spectrum and 87,5 MHz, depending on the particular geographical area, and an upper edge that is this standard is intended to include such small deviations combined andofreturn spectrums HFC cable systems and excludes any guard band typically inforward the range 300 MHz to 860 in MHz depending on implementation 3.2 3.3 3.2 full path band guard band of forward path band and return path band in HFC cable systems, excluding any full spectrum combination unused frequency bandreturn between the upper edgecable of the usable and return spectrum theband lower combined forward and spectrums in HFC systems excludes anyand guard guard band edge of the usable forward spectrum in HFC cable systems 3.3 3.4 guard band networkfrequency element (NE) unused band return path band the and the frequency band between between the the upper upper edge edge of of the the usable usable return spectrum and lower active element in usable the outside plant path that is capable of receiving commands from a head-end lower edge the spectrum forward band insystems HFC cable systems edge of the of usable forward in HFC cable element (HE) in the head-end and, as necessary, providing status information and alarms back to the HE 3.4 network element (NE) 3.5 active element in the outside plant that is capable of receiving commands from a head-end open system element (HE) interconnection in the head-end (OSI) and, as necessary, providing status information and alarms framework of back to the HE International Organization for Standardization (ISO) standards for communication between multi-vendor systems that organizes the communication process into seven different categories that are placed in a layered sequence based on the relationship to the 3.5 user Each layer uses the layer immediately below it and provides services to the layer above open system interconnection (OSI) Layers through deal with end-to-end communication between the message source and framework of International Organization for Standardization (ISO) standards for commudestination, and layers through deal with network functions nication between multi-vendor systems that organizes the communication process into seven different categories that are placed in a layered sequence based on the relationship to the 3.6 user Each layer uses the layer immediately below it and provides services to the layer above physical layer Layers (PHY) through deal with end-to-end communication between the message source and layer in the System (OSI)functions architecture; the layer that provides destination, and Open layers throughInterconnection deal with network services to transmit bits or groups of bits over a transmission link between open systems and which entails electrical, mechanical and handshaking procedures 3.6 physical (PHY) layer 3.7 layer in the Open System Interconnection (OSI) architecture; the layer that provides return servicesspectrum to transmit bits or groups of bits over a transmission link between open systems and pass-band of electrical, frequencies in HFC cable systems withprocedures a lower edge of MHz and an upper which entails mechanical and handshaking edge that is typically in the range of 42 MHz to 65 MHz depending on the particular geographical area 3.7 return spectrum return path band 3.8 pass-band of frequencies in HFC cable systems a lower of edge MHz of and5 an upper continuous set of frequencies in HFC cablewith systems withedge a lower MHz and transponder edge thatedge is typically in the inrange of 42ofMHz to 65 MHz depending an upper that is typically the range 42 MHz to 65 MHz dependingononthe the particular particular device in the area outside plant that interfaces to outside plant NEs and relays status and alarm geographical area geographical information to the HE It can interface with an active NE via an arrangement of parallel analogue, parallel digital and serial ports 3.8 transponder device in the outside plant that interfaces to outside plant NEs and relays status and alarm information to the HE It can interface with an active NE via an arrangement of parallel analogue, parallel digital and serial ports 3.7 return spectrum BS pass-band of frequencies in HFC cable systems with a lower edge that is typically in the range of 42 MHz to 65 MHz geographical area EN 60728-7-1:2005+A1:2015 edge of MHz and an upper EN 60728-7-1:2005+A1:2015 depending on the particular 3.8 transponder device in the outside plant that interfaces to outside plant NEs and relays status and alarm Page EN 60728−7−1:2005 information to the HE It can interface with an active NE via an arrangement of parallel analogue, parallel digital and serial ports 3.9 un-modulated carrier carrier resting on the ‘mark’ frequency rather than on the channel’s centre frequency 3.10 Abbreviated terms ANSI American National Standards Institute BER Bit Error Rate C/R Carrier-to-Noise Ratio C/(N+I) Carrier to Noise-plus-Interference Ratio CW Continuous Wave EMC Electromagnetic Compatibility FSK Frequency Shift Keying HE Head-end Element HFC Hybrid Fibre Coax HMS Hybrid Management Sub-Layer LSB Least Significant Bit MSB Most Significant Bit NE Network Element MAC Media Access Control OSP Outside Plant PHY Physical RF Radio Frequency SCTE Society of Cable Telecommunications Engineers Page BS EN 60728-7-1:2005+A1:2015 EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 HMS reference architecture forward and return channel specifications The reference architecture for the HMS series of specifications is illustrated in Figure Fiber Node RF TRANSMITER RF Amplifier Chain Status Monitoring Device Diplexer Laser Optical Receiver RF RECEIVER RF Splitter Headend Status Monitoring Equipment * Optical Receiver RF RECEIVER B Laser RF Combiner C RF TRANSMITER A * The diplexer filter may be included as part of the network element to which the transponder interfaces, or it may be added separately by the network operator IEC 2293/03 Figure – HMS reference architecture diagram All quantities relating to forward channel transmission or reverse channel reception are measured at point A in Figure All quantities relating to forward channel reception or reverse channel transmission are measured at point B for two-port devices and point C for single port devices as shown in Figure 4.1 HMS specification documents A list of documents in the HMS specifications family is provided in Table Table – HMS document family HMS notation Title SCTE HMS PHY HMS Outside Plant Status Monitoring – Physical (PHY) Layer Specification SCTE HMS MAC HMS Outside Plant Status Monitoring – Media Access Control (MAC) Layer Specification SCTE HMS PSTIB HMS Outside Plant Status Monitoring – Power Supply to Transponder Interface Bus (PSTIB) Specification SCTE HMS ALARMS MIB HMS Alarms Management Information Base SCTE HMS COMMON MIB HMS Common Management Information Base SCTE HMS FIBERNODE MIB HMS Fiber Node Management Information Base SCTE HMS PROPERTY MIB HMS Alarm Property Management Information Base SCTE HMS PS MIB HMS Power Supply Management Information Base SCTE ROOT MIB SCTE Root Management Information Base SCTE HMS GEN MIB HMS Power Supply Generator Management Information Base SCTE HMS TIB MIB HMS Transponder Interface Bus Management Information Base SCTE HMS DOWNLOAD MIB HMS Transponder Firmware Download Management Information Base SCTE HMS TREE MIB HMS Root Object Identifiers Management Information Base Page Page EN 60728−7−1:2005 BS EN 60728-7-1:2005+A1:2015 EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 4.2 Functional assumptions 4.2 Functional assumptions 4.2.1 Forward and return spectrum 4.2.1 Forward andpath return spectrum 4.2.1 Forward band and return path band The forward spectrum in HFC cable systems refers to the pass band of frequencies with a The band in in HFC systems frequencies with forward spectrum systems refers to to the the pass bandset of of frequencies with a lowerforward edge ofpath between 48 MHz cable and 87,5 MHz, refers depending oncontinuous the particular geographical area, lower edge of between 48 MHz and and 87,5 MHz, depending on MHz theonparticular geographical area, a lower edge ofedge between 48 typically MHz depending the860 particular geographical and an upper that is in87,5 the MHz, range of 300 to MHz depending on and an edge thatthat is typically in inthe MHzchannels to 1860 depending on area, andupper an upper edge is typically the range ofor300 to 000MHz MHzassumed depending implementation Analogue television signals inrange MHzof MHz are to be implementation Analogue television signals in narrowband MHz or MHz assumed to be present on the forward spectrum as well as other andchannels widebandare digital signals implementation present on the forward spectrum as well as other narrowband and wideband digital signals spectrum in HFC cable refers torefers the pass band of band frequencies with a lower The return return path band in HFCsystems cable systems to the pass of frequencies with The return inan HFC cable systems the pass band of frequencies a lower edge of edge spectrum MHz upper edge that refers is typically in in the ofof 42 to MHz a lower of 5and MHz and an upper edge that istotypically therange range 42MHz MHzwith to 65 edge of on MHz an upper edge that is Narrowband typically in and the range ofdigital 42 MHz to 65 MHz on theand particular geographical area Narrowband and wideband digital signals may depending the particular geographical area wideband signals may be depending on particular geographical area Narrowband and wideband digital signals may be present on the the return returnpath spectrum as as well asas analogue signals or present on the band well analoguetelevision television signalsin in66 MHz MHz or 88 MHz MHz be present on the return spectrum as well as analogue television signals in MHz or MHz channels channels channels The path band HFC cable systems to combined the combined forward return path fullfull spectrum in HFCincable systems refersrefers to the forward andand return spectrums The excludes full in HFC cable systems refers to the combined forward and return spectrums and guard band The guardThe band refers to the unused band between bands spectrum and any excludes any guard band guard band refers to thefrequency unused frequency band and upper excludes anyofguard band The guard band refers to the unused band between the the of usable return spectrum andband the lower of the usable forward between theedge upper edge the usable return path andedge the frequency lower edge of the usable the forward upper Specific edge of limits the return spectrum and and the return lower edge of band the usable forward spectrum forward and return spectrum for various geographical areas are path band usable on Specific limits on forward path for various spectrum limits on forward and detailed in Specific Table are geographical areas detailed in Table return spectrum for various geographical areas are detailed in Table Table – Spectral limits3 by geographical (North America Table – Spectral limitsarea by geographical area and Europe) Table – Spectral limits by geographical area Return path band spectrum Geography Geography North America North America Europe Europe Europe Europe Europe Europe Return spectrum Minimum Guard band frequency lower limit Minimum Guard band frequency lower limit MHz 42 MHz MHz 42 MHz MHz 30 MHz MHz 30 MHz MHz 50 MHz MHz 50 MHz MHz 65 MHz MHz 65 MHz Forward path band spectrum Forward spectrum Guard band Maximum upper limit frequency Guard band Maximum upper limit frequency 48 MHz GHz 1 000 MHz 48 MHz GHz 47 MHz 862 862MHz MHz 47 MHz 862 MHz 1862 000MHz MHz 70 MHz 70 MHz 862 MHz 1862 000MHz MHz 87,5 MHz 87,5 MHz 862 MHz 4.2.2 Transmission levels 4.2.2 Transmission levels The nominal level of the forward spectrum HMS is targeted to be no – forward path band carrier(s) HMS carrier(s) is targeted to higher be no than higher ThedB nominal of the forward spectrum HMS carrier carrier(s) targeted to bepower no higher – 10 relative to analogue video nominal carrier levels Theisnominal power level oflevel the than return than – 10 dB level relative to analogue video nominal levels The nominal of the 10 dB relative tocarrier(s) analogue video levels The nominal power level of the margin return spectrum HMSband will be nominal as low as possible achieve required margin above return path HMS carrier(s) will carrier be as low as to possible to the achieve the required spectrum HMS will Uniform be power as low as loading possible tounit achieve theisrequired margin above noise and interference Uniform loading per per unit bandwidth followed in above noise and carrier(s) interference power bandwidth iscommonly commonly followed noise and interference Uniform power per unit bandwidth isestablished commonlyby followed in signal levelsononthe the spectrum, with specific levels the setting signal levels return return pathloading band , with specific levelsestablished by the cable setting signal levels on thethe return spectrum, with specific levels established byratios the cable operator to achieve achieve the required carrier-to-noise andcarrier-to-interference carrier-to-interference ratios network operator to required carrier-to-noise and network operator to achieve the required carrier-to-noise and carrier-to-interference ratios 5 Physical layer specification Physical layer specification This clause describes version 1.0 of the HMS PHY layer specification The PHY layer This clause describes version 1.0 of the of HMS PHY specification The The PHY layer describes rules that govern the transmission bytes fromlayer one device to another specific describes rules govern thelayer transmission of bytes from one device to another The specific requirements of that the HMS PHY are detailed in this clause requirements of the HMS PHY layer are detailed in this clause 5.1 Separate forward and return channels 5.1 Separate forward and return channels The one-way communication channel from the HE to a managed OSP NE is referred to as the The one-way communication channel from the HE to a managed OSP NEOSP is referred to as forward channel The one-way communication channel from a managed NE to the HEthe is forward channel one-way communication channeland from managed OSP NE the HEon is referred to as theThe return channel Both the forward thea return channels areto placed referred centre to as the return channel Both and the return forward and the centre return frequencies channels are on specific frequencies The forward channels’ areplaced different specificthe centre forward and return channels’ centre frequencies are different Since NEsfrequencies only listen The to the forward channel, they cannot listen to return channel Since the NEsfrom onlyother listenNEs to the theyiscannot listen to return channel transmissions Thisforward channelchannel, separation a result of the sub-band split transmissions from other NEs This channel separation is a result of the sub-band split between the forward and return portions of the typical HFC plant spectrum between the forward and return portions of the typical HFC plant spectrum Page 10 BS EN 60728-7-1:2005+A1:2015 EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 5.2 Single forward and return path channels To keep management of carrier frequencies simple, each HMS-based status monitoring system has a single forward channel and a single return channel This does not preclude the use of multiple monitoring systems, each with its own individual forward and return RF channels 5.3 Byte-based transmission The physical layer provides byte-based communications in both directions, between a managed NE and the head-end It delivers bytes from one end of the channel to the other end of the channel 5.4 Byte formats and transmission order Bytes on both forward and return channels are ten bits in length They contain one start bit, eight bits of data, and one stop bit The start bit has binary value ‘0’, and the stop bit has binary value ‘1’ Throughout this standard, bits labelled ‘0’ are the least significant bits (LSBs) The LSB of a single byte is always transmitted first following the start bit Bits labelled ‘7’ are the most significant bits (MSBs) The MSB of a single byte is always transmitted last followed by the stop bit The transmission order is summarized in Figure IEC 2294/03 Figure – Bit transmission order 5.5 Packet-based transmission Transmission in both forward and return channels is implemented using packets Transmission on the forward channel is continuous; there is no gap in RF output between packets Packets are separated by a continuous sequence of bits having value ‘1’, i.e ‘mark’ tone The channel is said to ‘rest on mark’ between packets Transmission on the return channel is accomplished with burst packets Packets are separated by periods of silence when the transmitter is turned off Burst communication is used in the return path of HFC systems because of its ability to solve the many-to-one multiple access characteristic by allowing terminals to ‘take turns’ transmitting 5.6 Duplex operation The physical layer implementation in HMS-compliant transponders interfacing to OSP NEs shall support half-duplex operation There is no requirement for full-duplex operation 5.7 Forward and return channel specifications HMS PHY channel RF and modulation specifications for the forward and return communications channels are shown in Table Descriptions of each parameter are provided following that table Any exceptions to compliance with the specifications in Table will be specifically noted in this document as necessary 10 BS EN 60728-7-1:2005+A1:2015 Page 11 EN 60728−7−1:2005 EN 60728-7-1:2005+A1:2015 Table – HMS PHY channel RF and modulation specifications Item Transmit power level HE note Transponder +100 dB(µV) to +111 dB(µV) +85 dB(µV) to +105 dB(µV) Transmit power accuracy ±2 dB ±3 dB Transmit power step size dB dB Transmitter frequencies note (reference North American) 48 MHz to 162 MHz, in MHz bands: 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) 19) 48 MHz to 54 MHz 54 MHz to 60 MHz (Channel 2) 60 MHz to 66 MHz (Channel 3) 66 MHz to 72 MHz (Channel 4) 72 MHz to 78 MHz 78 MHz to 84 MHz (~ Channel 5) 84 MHz to 90 MHz (~ Channel 6) 90 MHz to 96 MHz (A-5) 96 MHz to 102 MHz (A-4) 102 MHz to 108 MHz (A-3) 108 MHz to 114 MHz (A-2) 114 MHz to 120 MHz (A-1) 120 MHz to 126 MHz (Channel 14) 126 MHz to 132 MHz (Channel 15) 132 MHz to 138 MHz (Channel 16) 138 MHz to 144 MHz (Channel 17) 144 MHz to 150 MHz (Channel 18) 150 MHz to 156 MHz (Channel 19) 156 MHz to 162 MHz (Channel 20) MHz to 21 MHz, in MHz bands: 1) 2) 3) 4) MHz to MHz MHz to 13 MHz 13 MHz to 17 MHz 17 MHz to 21 MHz Transmitter tuning range Fully agile within each of the specified MHz frequency operating ranges Fully agile within each of the specified MHz frequency operating ranges Transmitter frequency step size 100 kHz 100 kHz Transmitter frequency accuracy not e ±10 kHz ±10 kHz Transmitter cut-off Not applicable 1s Transmitter spurious emissions outside operating channel bandwidth during ON state note path band –55 dB over the full path band –65 dB over the forward forward spectrum full spectrum Transmitter conducted spurious emissions outside operating channel bandwidth during OFF state Not applicable (referenced to the unmodulated forward (referenced to the unmodulated forward carrier) carrier) Single port devices: 25 dB(µV), MHz to 1000 MHz Dual port devices, Transmit port: 25 dB(µV), MHz to 200 MHz 45 dB(µV), 200 MHz to 1000 MHz Dual port devices, Receive port: 45 dB(µV), MHz to 50 MHz 25 dB(µV), 50 MHz to 1000 MHz Spectral shape