prEN IEC 60728-114:2023

SLOVENSKI STANDARD
01-maj-2023
Optični prenosni sistemi s tehnologijo RFoG (TA5)
Optical transmission systems using RFoG technology (TA5)
Ta slovenski standard je istoveten z: prEN IEC 60728-114:2023
ICS:
33.160.01 Avdio, video in avdiovizualni Audio, video and audiovisual
sistemi na splošno systems in general
33.180.20 Povezovalne naprave za Fibre optic interconnecting
optična vlakna devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

100/3883/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60728-114 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2023-03-24 2023-06-16
SUPERSEDES DOCUMENTS:
100/3766/CD, 100/3805B/CC
IEC TA 5 : CABLE NETWORKS FOR TELEVISION SIGNALS, SOUND SIGNALS AND INTERACTIVE SERVICES
SECRETARIAT: SECRETARY:
Japan Mr Hiroo Tamura
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

Other TC/SCs are requested to indicate their interest, if any, in
this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for Vote
(CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of
• any relevant patent rights of which they are aware and to provide supporting documentation,
• any relevant “in some countries” clauses to be included should this proposal proceed. Recipients are reminded that the
enquiry stage is the final stage for submitting "in some countries" clauses. See AC/22/2007.

TITLE:
Optical transmission systems using RFoG technology (TA5)

PROPOSED STABILITY DATE: 2027
NOTE FROM TC/SC OFFICERS:
This project was approved to proceed to the CDV stage at the TA5 meeting that was held on November 18.
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

IEC CDV 60728-114 © IEC 2023          – 2 –
2 CONTENTS
4 CONTENTS . 2
5 FOREWORD . 5
6 INTRODUCTION . 7
7 1 Scope . 8
8 2 Normative references . 8
9 3 Terms, definitions, symbols and abbreviations . 10
10 3.1 Terms and definitions . 10
11 3.2 Symbols . 15
12 3.3 Abbreviations . 15
13 4 System reference model . 16
14 5 RFoG ONU reference architecture . 17
15 6 Method of measurements . 19
16 6.1 Optical power . 19
17 6.2 Centroidal wavelength and spectral width under modulation. 19
18 6.3 Optical wavelength. 19
19 6.4 Linewidth and chirping of transmitters with single mode lasers . 19
20 6.5 Optical modulation index . 19
21 6.6 Reference output level of an optical receiver . 19
22 6.7 Noise parameters of optical transmitters and optical receivers . 20
23 6.8 Relative intensity noise (RIN), optical modulation index and equivalent
24 input noise current (EINC) . 20
25 6.9 Signal level and signal-to-noise ratio . 20
26 6.10 Noise power ratio (NPR) . 20
27 6.11 Signal-to-noise ratio defined by optical signal . 20
28 6.12 Signal-to-crosstalk ratio (SCR) . 20
29 7 System performance requirements . 21
30 7.1 Digital data system . 21
31 7.1.1 ODN . 21
32 7.1.2 Performance allocation . 21
33 7.2 Forward path and return path frequency split . 22
34 8 RFoG equipment specifications . 22
35 8.1 General specifications . 22
36 8.1.1 Safety . 22
37 8.1.2 Electromagnetic compatibility (EMC) . 22
38 8.1.3 Environmental conditions . 23
39 8.1.4 Marking . 23
40 8.2 R-ONU . 23
41 8.2.1 Indicators . 23
42 8.2.2 R-ONU optical isolation specifications . 24
43 8.2.3 R-ONU’s optional pass through filter . 24
44 8.2.4 R-ONU forward path receiver specifications . 25
45 8.2.5 Return path performance of R-ONU . 27
46 8.3 Headend specifications . 31

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47 8.3.1 Headend forward path specifications . 31
48 8.3.2 Headend return path specifications . 31
49 Annex A (informative) Implementation notes . 33
50 Annex B (informative) System loss specification . 35
51 B.1 General . 35
52 B.2 Forward path considerations . 35
53 B.3 Return path considerations . 36
54 Annex C (informative) Optical beat interference . 39
55 C.1 General . 39
56 C.2 Operating conditions of ODN . 39
57 C.3 Operating conditions of optical receiver at the headend system . 39
58 C.4 Operating conditions of CMTS . 40
59 C.5 Environmental conditions . 40
60 C.6 Relation between optical transmission loss and OMI . 40
61 C.7 Design margin of ODN . 41
62 C.8 Example of system design . 42
63 C.9 Method of measurement of OBI . 43
64 C.9.1 Purpose . 43
65 C.9.2 Measurement setup . 43
66 C.9.3 Example of measurement conditions . 43
67 C.9.4 Procedure . 44
68 C.9.5 Presentation of results . 44
69 C.10 Method of measurement of OBI (measurement with CW signals) . 44
70 C.10.1 Purpose . 44
71 C.10.2 Measurement setup . 44
72 C.10.3 Procedure . 45
73 Annex D (informative) Outdoor housings for R-ONU protection . 46
74 Annex E (informative) Effect of off-state optical power on SNR ratio of transmission
75 signal . 47
76 Bibliography . 49
78 Figure 1 – Optical system reference model for RFoG . 17
79 Figure 2 – Principle schematics of R-ONU . 18
80 Figure 3 – Measurement of optical wavelength using WDM coupler . 19
81 Figure 4 – Optional xPON pass through filter block diagram . 24
82 Figure 5 – R-ONU turn-on and turn-off diagram . 31
83 Figure A.1 – Placement of attenuators when system loss is too low . 34
84 Figure B.1 – Performance allocation of the return path transmission system . 36
85 Figure B.2 – Section SNR specification for SDU and MDU in-house cabling. 38
86 Figure C.1 – Optical transmission loss and OMI . 41
87 Figure C.2 – ODN design margin . 41
88 Figure C.3 – Setup used for the measurement of OBI . 43
89 Figure C.4 – Setup used for the measurement of OBI (CW method) . 45
91 Table 1 – ODN specifications . 21

IEC CDV 60728-114 © IEC 2023          – 4 –
a
92 Table 2 – RF frequencies . 22
93 Table 3 – R-ONU Optical Isolation . 24
94 Table 4 – R-ONU’s optional xPON pass through filter . 25
95 Table 5 – Classification of R-ONU optical receivers . 25
96 Table 6 – Data publication requirements for R-ONU optical receivers . 26
97 Table 7 – Recommendations for R-ONU optical receivers . 26
98 Table 8 – Performance requirements for R-ONU optical receivers . 27
99 Table 9 – Classes of optical return path transmitters . 27
100 Table 10 – Data publication requirements for optical return path transmitters . 27
101 Table 11 – Performance requirements for optical parameters and interfaces . 28
102 Table 12 – Electrical properties requirements for R-ONU optical return path
103 transmitters. 28
104 Table 13 – R-ONU turn-on and turn-off specifications . 29
105 Table 14 – Data publication requirements for return path optical receivers . 32
106 Table 15 – Performance requirements for optical return path receivers . 32
107 Table C.1 – Operating conditions related to ODN parameters . 39
108 Table C.2 – Operating conditions related to ODN parameters . 40
109 Table C.3 – Environmental conditions for system evaluation . 40
110 Table C.4 – Factors affecting the transmission loss of ODN . 42
111 Table C.5 – System design example 1 . 42
112 Table C.6 – System design example 2 . 42
113 Table C.7 – Example of list of measurement conditions . 43
114 Table C.8 – Presentation of OBI measurement results . 44
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118 INTERNATIONAL ELECTROTECHNICAL COMMISSION
119 ____________
121 CABLE NETWORKS FOR TELEVISION SIGNALS,
122 SOUND SIGNALS AND INTERACTIVE SERVICES –
124 Part 114: Optical transmission systems using RFoG technology
126 FOREWORD
127 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
128 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
129 co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
130 in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
131 Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
132 preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
133 may participate in this preparatory work. International, governmental and non-governmental organizations liaising
134 with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
135 Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
136 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
137 consensus of opinion on the relevant subjects since each technical committee has representation from all
138 interested IEC National Committees.
139 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
140 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
141 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
142 misinterpretation by any end user.
143 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
144 transparently to the maximum extent possible in their national and regional publications. Any divergence between
145 any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
146 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
147 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
148 services carried out by independent certification bodies.
149 6) All users should ensure that they have the latest edition of this publication.
150 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
151 members of its technical committees and IEC National Committees for any personal injury, property damage or
152 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
153 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
154 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
155 indispensable for the correct application of this publication.
156 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
157 rights. IEC shall not be held responsible for identifying any or all such patent rights.
158 International Standard IEC 60728-14 has been prepared by technical area 5: Cable networks
159 for television signals, sound signals and interactive services, of IEC technical committee 100:
160 Audio, video and multimedia systems and equipment.
161 The text of this International Standard is based on the following documents:
NP Report on voting
100/3xxx/FDIS 100/3xxx/RVD
162 Full information on the voting for its approval can be found in the report on voting indicated in
163 the above table.
164 The language used for the development of this International Standard is English
165 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
166 accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

IEC CDV 60728-114 © IEC 2023          – 6 –
167 at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
168 described in greater detail at www.iec.ch/standardsdev/publications.
169 The list of all the parts of the IEC 60728 series, under the general title Cable networks for
170 television signals, sound signals and interactive services, can be found on the IEC website.
171 This standard follows closely (where applicable) the ANSI/SCTE 174 2018 standard “Radio
172 Frequency over Glass / Fiber-to-the-Home (RFoG) Specification / Extension”. In agreement with
173 SCTE major parts of ANSI/SCTE 174:2018 have been copied into this standard.
174 The committee has decided that the contents of this document will remain unchanged until the
175 stability date indicated on the IEC website under webstore.iec.ch in the data related to the
176 specific document. At this date, the document will be
177 • reconfirmed,
178 • withdrawn,
179 • replaced by a revised edition, or
180 • amended.
___________
SCTE = Society of Cable Telecommunications Engineers

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182 INTRODUCTION
183 Standards and other deliverables of the IEC 60728 series deal with cable networks including
184 equipment and associated methods of measurement for headend reception, processing and
185 distribution of television and sound signals, and for processing, interfacing and transmitting all
186 kinds of data signals for interactive services using all applicable transmission media. These
187 signals are typically transmitted in networks by frequency-multiplexing techniques.
188 • regional and local broadband cable networks,
189 • extended satellite and terrestrial television distribution systems,
190 • individual satellite and terrestrial television receiving systems,
191 and all kinds of equipment, systems and installations used in such cable networks, distribution
192 and receiving systems.
193 The extent of this standardization work is from the antennas and/or special signal source inputs
194 to the headend or other interface points to the network up to the terminal input of the customer
195 premises equipment.
196 The standardization work will consider coexistence with users of the RF spectrum in wired and
197 wireless transmission systems.
198 The standardization of any user terminals (i.e., tuners, receivers, decoders, multimedia
199 terminals, etc.) as well as of any coaxial, balanced and optical cables and accessories thereof
200 is excluded.
201 The Annexes provide the following information.
Annex A describes implementation notes with design consideration based on this
standard
Annex B describes the system loss specification
Annex C describes multiple CMTS operation
Annex D gives a design guideline of housings for R-ONU protection
Annex E contains information on the effect of off-state optical power on SNR of
transmission signal
IEC CDV 60728-114 © IEC 2023          – 8 –
203 CABLE NETWORKS FOR TELEVISION SIGNALS,
204 SOUND SIGNALS AND INTERACTIVE SERVICES –
206 Part 114: Optical transmission systems using RFoG technology
210 1 Scope
211 This part of IEC 60728 describes the system and equipment specification of FTTH/FTTB (fibre
212 to the home/fibre to the building) networks where information is transmitted in both, forward and
213 return path directions using RF subcarrier multiplexing technology, and where the return path
214 transmission uses additionally time division multiple access technique imposed by the
215 transmission of the return path signals using a TDMA (e.g. TDMA mode of DOCSIS) protocol.
216 Such systems are called RF over Glass (RFoG) and consist of an RFoG optical network unit
217 (R-ONU), an optical distribution network based on xPON structure, and an RFoG optical return
218 path receiver. This standard specifies the basic system parameters and methods of
219 measurement for RFoG systems in order to assess the system performance and its performance
220 limits.
221 The detailed description of physical layer is out of the scope of this standard and it does not
222 include IP transport technologies.
223 2 Normative references
224 The following documents, in whole or in part, are normatively referenced in this document and
225 are indispensable for its application. For dated references, only the edition cited applies. For
226 undated references, the latest edition of the referenced document (including any amendments)
227 applies.
228 IEC 60068-1:2013, Environmental testing – Part 1: General and guidance
229 IEC 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Test A: Cold
230 IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Test B: Dry heat
231 IEC 60068-2-6:2007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
232 IEC 60068-2-14:2009, Environmental testing – Part 2-14: Tests – Test N: Change of
233 temperature
234 IEC 60068-2-27:2008, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
235 IEC 60068-2-30:2005, Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic
236 (12 h + 12 h cycle)
237 IEC 60068-2-31:2008, Environmental testing – Part 2-31: Tests – Test Ec: Rough handling
238 shocks, primarily for equipment-type specimens
239 IEC 60068-2-40:1976, Environmental testing – Part 2-40: Tests – Test Z/AM: Combined
240 cold/low air pressure tests

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241 IEC 60529: Consolidated version from 2013, Degrees of protection provided by enclosures (IP
242 Code)
243 IEC 60728-2:2018, Cable networks for television signals, sound signals and interactive services
244 – Part 2: Electromagnetic compatibility of equipment
245 IEC 60728-3:2018, Cable networks for television signals, sound signals and interactive services
246 – Part 3: Active wideband equipment for cable networks
247 IEC 60728-6:2011, Cable networks for television signals, sound signals and interactive services
248 – Part 6: Optical equipment
249 IEC 60728-10:2014, Cable networks for television signals, sound signals and interactive
250 services – Part 10: System performance of return path
251 IEC 60728-11:2016, Cable networks for television signals, sound signals and interactive
252 services – Part 11: Safety
253 IEC 60728-13:2010, Cable networks for television signals, sound signals and interactive
254 services – Part 13: Optical systems for broadcast signal transmissions
255 IEC 60728-13-1:2017, Cable networks for television signals, sound signals and interactive
256 services – Part 13-1: Bandwidth expansion for broadcast signal over FTTH system
257 IEC 60728-106.202x, Cable networks for television signals, sound signals and interactive
258 services – Part 106: Optical equipment for systems loaded with digital channels only
259 IEC 60793-2-50:2018, Optical fibres – Part 2-50: Product specifications – Sectional
260 specification for class B single-mode fibres
261 IEC 60794-3-11:2010, Optical fibre cables – Part 3-11: Outdoor cables – Product specification
262 for duct, directly buried, and lashed aerial single-mode optical fibre telecommunication cables
263 IEC 60825-1:2014, Safety of laser products – Part 1: Equipment classification and requirements
264 IEC 61169-2:2007, Radio-frequency connectors – Part 2: Sectional specification – Radio
265 frequency coaxial connectors type 9,52
266 IEC 61169-24:2019, Radio-frequency connectors – Part 24: Sectional specification – Radio-
267 frequency coaxial connectors with screw coupling, typically for use in 75 Ω cable networks (type
268 F)
269 IEC 61280-1-1:2013, Fibre optic communication subsystem basic test procedures – Part 1-1:
270 Test procedures for general communication subsystems – Transmitter output optical power
271 measurement for single-mode optical fibre cable
272 IEC 61280-1-3:2010, Fibre optic communication subsystem test procedures – Part 1-3: General
273 communication subsystems – Central wavelength and spectral width measurement
274 IEC 61754-4:2013, Fibre optic interconnecting devices and passive components – Fibre optic
275 connector interfaces – Part 4: Type SC connector family
276 IEC TR 61931:1998, Fibre optic – Terminology

IEC CDV 60728-114 © IEC 2023          – 10 –
277 ISO/IEC/IEEE Standard 8802-3:2021, Standard for Ethernet
278 3 Terms, definitions, symbols and abbreviations
279 3.1 Terms and definitions
280 For the purposes of this document, the following terms and definitions apply.
281 ISO and IEC maintain terminological databases for use in standardization at the following
282 addresses:
283 • IEC Electropedia: available at http://www.electropedia.org/
284 • ISO Online browsing platform: available at https://www.iso.org/obp/ui
286 3.1.1
287 equivalent input noise current density
288 notional input noise current density which, when applied to the input of an ideal noiseless device,
289 produces an output noise current density equal in value to that observed at the output of the
290 actual device under consideration
291 Note 1 to entry: It can be calculated from the RF signal-to-noise ratio (see IEC 60728-106) of a device or system.
292 3.1.2
293 flatness
294 difference between the maximum and the minimum RF gain or attenuation not taking into
295 account the slope within the specified modulation frequency range of a device or system
296 3.1.3
297 headend system
298 system comprising modulators, demodulators, CMTS, an optical transmitter with optional optical
299 amplifiers and a WDM for the transmission of analogue video as well as digitally modulated
300 signals located at the central office side of the optical network
301 Note 1 to entry: The headend system is equipped with an optical return path receiver receiving digitally modulated
302 signals of data in the return path direction to enable e.g. VoIP, VOD and internet services.
303 Note 2 to entry: V-OLT is a part of the headend system and deals with video transmission in the forward path only.
304 3.1.4
305 local broadband cable network
306 network designed to provide sound and television signals as well as signals for interactive
307 services to a local area (e.g. one town or one village)
308 3.1.5
309 WDM device
310 wavelength selective branching device (used in WDM transmission systems) in which optical
311 signals can be transferred between two predetermined ports, depending on the wavelength of
312 the signal
313 3.1.6
314 noise power ratio
315 NPR
316 ratio of the signal power density to the power density of the combined noise and intermodulation
317 distortion
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318 3.1.7
319 off-state optical power
320 residual optical output power emitted from the fibre of the R-ONU when the laser is switched to
321 off-state
322 Note 1 to entry: In a typical burst mode transmitter, for fast switching operation, the laser bias may be kept near
323 the threshold bias level to avoid turn-on and turn-off delays. The off-state optical power affects the system
324 performance when a large number of transmitters are connected to the same distribution network.
325 3.1.8
326 optical amplifier
327 OA
328 optical waveguide device containing a suitably pumped, active medium which is able to amplify
329 an optical signal
330 [SOURCE: IEC TR 61931:1998, 2.7.75]
331 3.1.9
332 optical distribution network
333 ODN
334 passive optical network (PON) mainly consisting of optical fibres and splitters
335 3.1.10
336 optical receiver
337 Rx
338 receive fibre optic terminal device accepting at its input port a modulated optical carrier, and
339 providing at its output port the corresponding demodulated electrical signal (with the associated
340 clock, if digital)
341 Note 1 to entry: For the purposes of this standard, optical receivers may have more than one output port providing
342 electrical RF signals.
343 3.1.11
344 optical modulation index
345 optical modulation index m is defined as

φ - φ
h l
m =
(1)
+
φ φ
h l
346 where φ is the highest and φ is the lowest instantaneous optical power of the intensity
h l
347 modulated optical signal
348 Note 1 to entry: This definition does not apply to systems where the input signals are converted and transported as
349 digital baseband signals. In this case, the terms modulation depth or extinction ratio defined in 2.6.79 and 2.7.46 of
350 IEC TR 61931:1998 are used. A test procedure for extinction ratio is described in IEC 61280-2-2.
351 [SOURCE: IEC 60728-6:2011,3.1.10, modified – repetition of "optical modulation" has been deleted.]
352 3.1.12
353 optical return loss
354 return loss
355 ORL
356 ratio of the total reflected power to the incident power from an optical fibre, optical device, or
357 optical system, and defined as:

IEC CDV 60728-114 © IEC 2023          – 12 –

P
r
−10lg
(2)
P
i
where
P is the reflected power;
r
P is the incident power
i
358 Note 1 to entry: When referring to a reflected power from an individual component, reflectance is the preferred
359 term.
360 [SOURCE: IEC TR 61931:1998, 2.6.49]
361 Note 2 to entry: For the purposes of this standard, the term reflectance is used for optical amplifiers only. The term
362 optical return loss is used for ports of all other types of equipment.
363 Note 3 to entry: The term return loss is also used for electrical ports. The definition relates to electrical powers in
364 this case.
365 Note 4 to entry: The ratio is expressed in dB.
366 3.1.13
367 optical transmitter
368 Tx
369 transmit fibre optic terminal device accepting at its input port an electrical signal and providing
370 at its output port an optical carrier modulated by that input signal
371 Note 1 to entry: For the purposes of this standard, optical transmitters may have more than one input port accepting
372 electrical RF signals.
373 3.1.14
374 radio frequency over glass
375 RFoG
376 transmission technology on optical networks where information is transmitted in both, forward
377 and return path directions, using RF subcarrier multiplexing technology, and where the return
378 path transmission uses additionally time division multiple access technique imposed by the
379 transmission of the return path signals using a TDMA (e.g. TDMA mode of DOCSIS) protocol
380 3.1.15
381 reference output level of an optical receiver
382 offset x by which the electrical output level of an optical receiver can be calculated from the
383 optical input level at a modulation index of m = 0,05 using the following equation:
U = 2 P + x dB(µV)
(3)
opt,RX
384 where
385 U is the electrical output level in dB(µV)
386 P is the optical input level in dB(mW)
opt,RX
387 x is the reference output level in dB(µV)
388 3.1.16
389 responsivity
390 ratio of an optical detector’s electrical output to its optical input at a given wavelength
391 Note 1 to entry: The responsivity is expressed in ampere per watt (A/W) or volts per watt (V/W) of incident radiant
392 power.
393 Note 2 to entry: Sensitivity is sometimes used as an imprecise synonym for responsivity.

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394 [SOURCE: IEC 60050-731:1991, 731-06-36, modified – "given wavelength" has been added and Note 1 has been
395 clarified.]
396 Note 3 to entry: The wavelength interval around the given wavelength may be specified.
397 [SOURCE: IEC TR 61931:1998, 2.7.56]
398 3.1.17
399 relative intensity noise
400 RIN
401 ratio of the mean square of the intensity fluctuations in the optical power of a light source to the
402 square of the mean of the optical output power
−1
403 Note 1 to entry: The RIN is usually expressed in dB(Hz ) resulting in negative values.
404 Note 2 to entry: The value for the RIN can be calculated from the results of a RF signal-to-noise measurement for
405 the system.
406 [SOURCE: IEC 60728-106.202x, 4.15]
407 3.1.18
408 RFoG optical network unit
409 R-ONU
410 fibre optic terminal comprising an optical receiver for reception of analogue signals and an
411 optical transmitter for the transmission of analogue signals originating from the customer side
412 of the optical network and a coaxial interface for the transmission of analogue signals to the
413 customer network and reception of analogue signals from the customer network generally
414 consisting of digital data using a TDMA (e.g. TDMA mode of DOCSIS) protocol
415 3.1.19
416 signal-to-crosstalk ratio
417 SCR
418 level difference of desired signal level and worst case of other services single frequency
419 crosstalk signal measured at RF output port of optical receiver
420 Note 1 to entry: SCR is defined by the following equation:

R DU− (4)
SC OS
422 where
423 D is the nominal level of the desired signal in dB(µV) at RF output port of optical receiver;
424 U is the worst-case level of another service’s single frequency crosstalk in dB(µV) at RF output port
OS
425 of the optical receiver.
426 Note 2 to entry: SCR is expressed in dB.
427 3.1.20
428 signal-to-noise ratio
429 SNR
430 level difference of desired signal level and noise level
431 Note 1 to entry: SNR is defined for both, analogue and digital modulated signals in IEC 60728-13.
432 [SOURCE: IEC 60728-13:2010, 3.1.19]

=
IEC CDV 60728-114 © IEC 2023          – 14 –
433 3.1.21
434 slope
435 gain or attenuation difference at two defined frequencies between two ports of a device or
436 system
437 Note 1 to entry: In this standard the term slope relates only to the electrical gain or attenuation of equipment.
438 Note 2 to entry: In equipment for cable networks a line of best fit of the amplitude frequency response is considered
439 at the band limits.
440 [SOURCE: IEC 60728-106.202x, 4.10]
441 3.1.22
442 Brillouin scattering
443 SBS
444 non-linear scattering of optical radiation characterized by a frequency shift as for the Raman
445 scattering, but accompanied by a lower frequency (acoustical) vibration of the medium lattice;
446 the light is scattered backward with respect to the incident radiation
447 Note 1 to entry: In silica fibres the frequency shift is typically around 10 GHz.
448 [SOURCE: IEC TR 61931:1998, 2.1.88]
449 3.1.23
450 wavelength
451 distance covered in a period by the wavefront of a harmonic plane wave
452 [SOURCE: IEC TR 61931:1998, 2.2.9]
453 Note 1 to entry: The wavelength λ of light in vacuum is given by

c
λ =
(5)
f
454 where
455 c is the speed of light in vacuum (c ≈ 2,997 92 × 10 m/s);
456 f is the optical frequency.
457 Note 2 to entry: Although the wavelength in dielectric material such as fibres is shorter than in vacuum, only the
458 wavelength of light in vacuum is used.

– 15 –            IEC CDV 60728-114 @ IEC2023
459 3.2 Symbols
460 The following graphical symbols are used in the figures of this standard. These symbols are
461 either listed in IEC 60617 or based on symbols defined in IEC 60617.
Optical transmitter Optical receiver
O
E
based on based on
[IEC 60617-S00213 [IEC 60617-S00213
E
O
(2001-07)] (2001-07)]
Optical amplifier
based on
Optical fibre
[IEC 60617-S00127
[IEC 60617-S01318
(2001-07) and
(2001-07)]
IEC 60617-S01239
(2001-07)]
Low-pass filter High-pass filter
[IEC 60617-S01248 [IEC 60617- S01247
(2001-07)] (2001-07)]
Directional coupler
based on
[IEC 60617-S00059
WDM WDM
(2001-07) and
IEC 60617-S01193
(2001-07)]
Electrical spectrum analyser
based on
[IEC 60617-S00059
P(f ) CM Cable modem
(2001-07) and
IEC 60617-S00910
(2001-07)]
Optical spectrum analyser
based on
[IEC 60617-S00059
TV set P(λ)
TV
(2001-07) and
IEC 60617-S00910
(2001-07)]
Variable attenuator
[IEC 60617-S01245 splitter/combiner
A
(2001-07)]
Sine-wave generator
based on
Polarisation control device
G
[IEC 60617-S00899,
[IEC 60617-S001430
(2001-07) and
(under consideration)]
IEC 60617-S01403
(2001-09)]
462 3.3 Abbreviations
463 The following abbreviations are used in this standard:
AC alternating current AGC automatic gain control
SNR signal-to-noise ratio CM cable modem
CMTS cable modem termination system CW continuous wave
DC direct current DOCSIS data over cable service
interface specification
DS downstream EINC equivalent input noise
current
IEC CDV 60728-114 © IEC 2023          – 16 –

EMC electromagnetic compatibility EPON Ethernet passive optical
network
(defined in ISO/IEC/IEEE
Standard 8802-3:2021)
FTTB Fibre to the building FTTH fibre to the home
GEPON Gigabit Ethernet passive optical GPON Gigabit-capable passive
network optical networks
(defined in ISO/IEC/IEEE Standard (defined in ITU-T
8802-3:2021) Recommendation G.984)
HFC hybrid fibre coaxial MDU multiple dwelling unit
NPR noise power ratio OBI optical beat interference
ODN optical distribution network OFDM orthogonal frequency division
multiplex
OMI optical modulation index ONU optical network unit
PON passive optical network QAM quadrature amplitude
modulation
QPSK quadrature phase shift keying RF radio frequency
RFoG RF over glass RIN relative intensity noise
R-ONU RFoG optical network unit R-RRX RFoF return path receiver
Rx (optical) receiver SBS stimulated Brillouin
scattering
SCR signal-to-crosstalk ratio SDU single dwelling unit
Tx (optical) transmitter US upstream
V-OLT video optical line termination unit V-ONU video optical network unit
WDM wavelength division multiplexing XG-PON 10-Gigabit-capable passive
optical network
(defined in ITU-T
Recommendation G.987)
xPON x- passive optical network,
“x” = G, E, 10 G, 10 GE, etc.
464 4 System reference model
465 Figure 1 shows the optical system reference model for forward path signal transmission and
466 return path signal transmission. The forward path signal transmission system is the subject of
467 IEC 60728-13. Compared to Figure 1 in IEC 60728-13:2010 the V-ONU has been replaced by
468 an R-ONU which includes a WDM and a burst mode return path transmitter in addition to the V-
469 ONU functionalities. The R-ONU is capable of transmitting interactive signals and is therefore
470 connected to a cable modem (CM) as well.

– 17 –            IEC CDV 60728-114 @ IEC2023
house network
Hheadend seadend sysytsetme m Ooptpticaicl adil dstriisbutrtiion netbutionw neorkt work House network
Forward path
f orward pat h
transmitter
transmitt er
Broadcast
broadcast
signals
E
signals
O
CCMMTTSS
forward port
f orward port
WDM
WDM
TVTV
CMCMTTS S
E
O
ret urn port
return port
O
E
R-Rx
R- RX
CM
CM
R-ONU
R- ONU
IEC  0717/14
472 Figure 1 – Optical system reference model for RFoG
473 Figure 1 illustrates the reference architecture of the system. In the reference architecture, the
474 headend system, the start of the RFoG system, comprises an optical forward path transmitter
475 operating nominally on 1 550 nm, optical amplification and splitting as appropriate, and an
476 optical return path receiver which receives optical return path signals on λ (defined below),
up
477 and converts them to RF form. The wavelength division multiplexer used to combine and
478 separate the two wavelengths is a part of the headend system. F
...