1、 International Telecommunication Union ITU-T O.174TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2009) SERIES O: SPECIFICATIONS OF MEASURING EQUIPMENT Equipment for the measurement of digital and analogue/digital parameters Jitter and wander measuring equipment for digital systems which are bas
2、ed on synchronous Ethernet technology Recommendation ITU-T O.174 ITU-T O-SERIES RECOMMENDATIONS SPECIFICATIONS OF MEASURING EQUIPMENT General O.1O.9 Maintenance access O.10O.19 Automatic and semi-automatic measuring systems O.20O.39 Equipment for the measurement of analogue parameters O.40O.129 Equi
3、pment for the measurement of digital and analogue/digital parameters O.130O.199Equipment for the measurement of optical channel parameters O.200O.209 Equipment to perform measurements on IP networks O.210O.219 Equipment to perform measurements on leased-circuit services O.220O.229 For further detail
4、s, please refer to the list of ITU-T Recommendations. Rec. ITU-T O.174 (11/2009) i Recommendation ITU-T O.174 Jitter and wander measuring equipment for digital systems which are based on synchronous Ethernet technology Summary Recommendation ITU-T O.174 specifies test equipment used to generate and
5、measure timing jitter and synchronization wander in digital systems based on synchronous Ethernet technology. History Edition Recommendation Approval Study Group 1.0 ITU-T O.174 2009-11-13 15 ii Rec. ITU-T O.174 (11/2009) FOREWORD The International Telecommunication Union (ITU) is the United Nations
6、 specialized agency in the field of telecommunications, information and communication technologies (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
7、them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication 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 IT
8、U-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas 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 us
9、ed for conciseness to indicate both a telecommunication administration and a recognized operating 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
10、 Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ 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
11、any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice 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 Pro
12、perty Rights, whether asserted by ITU members or others outside of the Recommendation development 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, i
13、mplementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior wr
14、itten permission of ITU. Rec. ITU-T O.174 (11/2009) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations and acronyms 3 5 Conventions 4 6 Functional block diagram . 4 7 Interfaces. 5 7.1 Synchronous Ethernet interfaces 5 7.2 External reference clock input 5 8 Jitter/wander gen
15、eration function . 5 8.1 Modulation source 5 8.2 Clock generator 5 8.3 Digital test pattern generator 6 8.4 Sinusoidal jitter/wander generation function 6 8.5 TDEV wander generation function 7 8.6 MTIE wander generation function . 7 9 Jitter measurement function 8 10 Wander measurement function . 8
16、10.1 Measurement of maximum relative time interval error (MRTIE) 8 11 Operating environment . 9 Appendix I Measurement guidelines for wander measurement 10 I.1 TDEV/MTIE wander tolerance 10 I.2 TDEV wander transfer . 12 Rec. ITU-T O.174 (11/2009) 1 Recommendation ITU-T O.174 Jitter and wander measur
17、ing equipment for digital systems which are based on synchronous Ethernet technology 1 Scope The test equipment specified in this Recommendation consists principally of a jitter/wander measurement function and a jitter/wander generation function. Measurements can be performed at the physical layer o
18、f synchronous Ethernet systems. A bit error rate test set may be part of the same equipment or may be physically separate. ITU-T O.172 specifies the test equipment for generation and measurement of jitter and wander in digital systems based on the synchronous digital hierarchy (SDH). ITU-T G.8261, I
19、TU-T G.8262 and ITU-T G.8264 should be read in conjunction with this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions
20、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 references listed below. A list of the currently valid ITU
21、-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. ITU-T G.691 Recommendation ITU-T G.691 (2006), Optical interfaces for single channel STM-64 and other SDH systems with optica
22、l amplifiers. ITU-T G.703 Recommendation ITU-T G.703 (2001), Physical/electrical characteristics of hierarchical digital interfaces. ITU-T G.705 Recommendation ITU-T G.705 (2000), Characteristics of plesiochronous digital hierarchy (PDH) equipment functional blocks. ITU-T G.781 Recommendation ITU-T
23、G.781 (1999), Synchronization layer functions. ITU-T G.783 Recommendation ITU-T G.783 (2006), Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks. ITU-T G.810 Recommendation ITU-T G.810 (1996), Definitions and terminology for synchronization networks. ITU-T G.811 Recom
24、mendation ITU-T G.811 (1997), Timing characteristics of primary reference clocks. ITU-T G.812 Recommendation ITU-T G.812 (2004), Timing requirements of slave clocks suitable for use as node clocks in synchronization networks. ITU-T G.813 Recommendation ITU-T G.813 (2003), Timing characteristics of S
25、DH equipment slave clocks (SEC). ITU-T G.822 Recommendation ITU-T G.822 (1988), Controlled slip rate objectives on an international digital connection. ITU-T G.823 Recommendation ITU-T G.823 (2000), The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy
26、. 2 Rec. ITU-T O.174 (11/2009) ITU-T G.824 Recommendation ITU-T G.824 (2000), The control of jitter and wander within digital networks which are based on the 1544 kbit/s hierarchy. ITU-T G.825 Recommendation ITU-T G.825 (2000), The control of jitter and wander within digital networks which are based
27、 on the synchronous digital hierarchy (SDH). ITU-T G.957 Recommendation ITU-T G.957 (1999), Optical interfaces for equipments and systems relating to the synchronous digital hierarchy. ITU-T G.959.1 Recommendation ITU-T G.959.1 (2008), Optical transport network physical layer interfaces. ITU-T G.801
28、0 Recommendation ITU-T G.8010/Y.1306 (2004), Architecture of Ethernet layer networks. ITU-T G.8110.1 Recommendation ITU-T G.8110.1/Y.1370.1 (2006), Architecture of Transport MPLS (T-MPLS) layer network. ITU-T G.8261 Recommendation ITU-T G.8261/Y.1361 (2008), Timing and synchronization aspects in pac
29、ket networks. ITU-T G.8262 Recommendation ITU-T G.8262/Y.1362 (2007), Timing characteristics of synchronous Ethernet equipment slave clock (EEC). ITU-T G.8264 Recommendation ITU-T G.8264/Y.1364 (2008), Distribution of timing information through packet networks. ITU-T O.3 Recommendation ITU-T O.3 (19
30、92), Climatic conditions and relevant tests for measuring equipment. ITU-T O.150 Recommendation ITU-T O.150 (1996), General requirements for instrumentation for performance measurements on digital transmission equipment. ITU-T O.171 Recommendation ITU-T O.171 (1997), Timing jitter and wander measuri
31、ng equipment for digital systems which are based on the plesiochronous digital hierarchy (PDH). ITU-T O.172 Recommendation ITU-T O.172 (2005), Jitter and wander measuring equipment for digital systems which are based on the synchronous digital hierarchy (SDH). IEEE 802.3 IEEE Standard 802.3-2008, In
32、formation technology Telecommunications and information exchange between 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 Definitions This Recommendation uses
33、 the following terms defined elsewhere: 3.1 Ethernet synchronization message channel: ITU-T G.8264. 3.2 non-sync operation mode: ITU-T G.8264. 3.3 synchronization network clock: ITU-T G.8261. 3.4 synchronous operation mode: ITU-T G.8264. 3.5 time interval error function: ITU-T G.810. 3.6 (timing) ji
34、tter: ITU-T G.810. Rec. ITU-T O.174 (11/2009) 3 3.7 wander: ITU-T G.810. Note that ITU-T G.810 and ITU-T G.8261 provide additional definitions and abbreviations used in timing and synchronization Recommendations. They also provide background information on the need to limit phase variation and impai
35、rments on digital systems. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: EEC synchronous Ethernet Equipment Clock ESMC Ethernet Synchronization Messaging Channel ETH Ethernet MAC layer network ETY Ethernet PHY layer network GE Gigabit Ethernet IP Int
36、ernet Protocol IWF InterWorking Function LPF Low-Pass Filter MTIE Maximum Time Interval Error MRTIE Maximum Relative Time Interval Error NE Network Element NRZ Non Return to Zero PDH Plesiochronous Digital Hierarchy PDU Protocol Data Unit PLL Phase-Locked Loop ppm parts per million PRBS Pseudo Rando
37、m Binary Sequence PRC Primary Reference Clock QL Quality Level RTIE Relative Time Interval Error SDH Synchronous Digital Hierarchy SEC Synchronous digital hierarchy Equipment Clock SSM Synchronization Status Message SSU Synchronization Supply Unit STM-N Synchronous Transport Module, level N TDEV Tim
38、e DEViation TIE Time Interval Error UI Unit Interval UIpp Unit Interval, peak-to-peak 4 Rec. ITU-T O.174 (11/2009) 5 Conventions The jitter/wander measurement function in this Recommendation applies to synchronous Ethernet interfaces. Jitter measurement functions for legacy Ethernet are defined part
39、ly in IEEE 802.3. 6 Functional block diagram Figure 1 shows the general block diagram of the equipment and identifies the main functions covered in this Recommendation. The figure does not describe a specific implementation. Figure 1 Functional block diagram for jitter and wander test set Test signa
40、l input*2TDEV result TIE/RTIE result MTIE/MRTIE result Jitter result Jitter measurement function Wander measurement function *2Jitter measurement function in this figure is applicable to Synchronous Ethernet interfaces. Interfaces Reference timing signal Phase detector Measurementfilter Reference ti
41、ming signal Measurementfilter Phase detector MTIE/MRTIEcalculation External reference clock input TDEV calculation Jitter/wandergeneration function Interfaces External reference clock input Wander modulation source Digital testpattern generator Clock generator Clock generator Test signal output Refe
42、rence timing signal output Jitter modulation source Rec. ITU-T O.174 (11/2009) 5 7 Interfaces 7.1 Synchronous Ethernet interfaces The equipment shall be capable of operating at one or more of the following Ethernet interfaces. Table III.1 of ITU-T G.8262 lists the interfaces supporting synchronous E
43、thernet. 7.2 External reference clock input The measuring equipment shall support reference data signals at bit rates of 1 544 kbit/s or 2 048 kbit/s. If 2 048 kbit/s can be accepted, the equipment shall also accept a clock signal at 2 048 kHz as a reference. The characteristics of clock signals sha
44、ll be in accordance with ITU-T G.703. 8 Jitter/wander generation function Tests of digital equipment may be made with either a jittered, wandered or a non-jittered/wandered digital signal. This will require the digital test pattern generator, clock generator and modulation source shown in Figure 1.
45、8.1 Modulation source The modulation source, required to perform tests conforming to relevant Recommendations may be provided within the clock generator and/or digital test pattern generator, or may be provided separately. This Recommendation defines a sinusoidal modulation source for jitter generat
46、ion. The modulation source for wander generation is defined as one of the following three signals. Sinusoidal. Time deviation (TDEV) wander (noise): White Gaussian noise filtered to obtain required TDEV characteristic. Maximum time interval error (MTIE) wander: Test signal to obtain required MTIE or
47、 maximum relative time interval error (MRTIE) characteristic. The sinusoidal jitter/wander, TDEV wander and MTIE wander generation functions are defined in clauses 8.4, 8.5 and 8.6, respectively. 8.2 Clock generator It shall be possible to phase-modulate the clock generator from the modulation sourc
48、e and to indicate the peak-to-peak phase deviation of the modulated signal. The generated peak-to-peak wander and the modulating frequencies shall meet the minimum requirements of Figure 2. The generated peak-to-peak jitter and the modulating frequencies for EEC options 1 and 2 shall meet IEEE 802.3
49、. The Ethernet measurement methodology is defined in IEEE 802.3. The applicability to jitter measurement in a synchronization network environment is for further study. 8.2.1 Accuracy of clock generator The frequency deviation of the internal clock signal from its nominal value shall be less than 4.6 ppm excluding locked operation. As an option, the clock generator may provide adjustable frequency offset of sufficient magnitude to facilitate tests across the clock
