1、 International Telecommunication Union ITU-T O.172TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2005) 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 the synchronous digital hierarchy (SDH) ITU-T Recommendation O.172 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.
3、129 Equipment for the measurement of digital and analogue/digital parameters O.130O.199 Equipment for the measurement of optical channel parameters O.200O.209 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. O.172 (04/2005) i ITU-T Recommendation O.172 Jitter and wa
4、nder measuring equipment for digital systems which are based on the synchronous digital hierarchy (SDH) Summary This Recommendation specifies instrumentation that is used to generate and measure jitter and wander in digital systems based on the SDH. Measurement requirements for both SDH line interfa
5、ces and SDH tributary interfaces operating at PDH bit rates are addressed in this Recommendation. The requirements for the characteristics of the jitter and wander measuring equipment that are specified in this Recommendation must be adhered to in order to ensure consistency of results between equip
6、ment produced by different manufacturers. Source ITU-T Recommendation O.172 was approved on 13 April 2005 by ITU-T Study Group 4 (2005-2008) under the ITU-T Recommendation A.8 procedure. Keywords Input jitter tolerance, Input wander tolerance, Jitter generation, Jitter measurement, Jitter transfer f
7、unction, Output jitter, Output wander, Phase transients, Pointer jitter, Pointer sequence generation, Wander generation, Wander measurement, Wander noise transfer. ii ITU-T Rec. O.172 (04/2005) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the f
8、ield of telecommunications. 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
9、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 ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
10、 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 used for conciseness to indicate both a telecommunication administration and a re
11、cognized 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 Recommendation is achieved when all of these mandatory provisions are met. The
12、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 any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility t
13、hat 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 Property Rights, whether asserted by ITU members or others outside of the Recommend
14、ation 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, implementors are cautioned that this may not represent the latest information and
15、 are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. O.172 (04/2005) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative re
16、ferences 1 2.2 Informative references 2 3 Definitions 2 4 Abbreviations 3 5 Conventions 3 6 Functional block diagram . 4 7 Interfaces. 4 7.1 Optical interfaces 4 7.2 Electrical interfaces 5 7.3 External reference clock input 5 7.4 Input interface sensitivity . 5 8 Jitter/wander generation function .
17、 5 8.1 Modulation source 5 8.2 Clock generator 6 8.3 Digital test pattern generator 6 8.4 Pointer sequence generator. 7 8.5 Minimum jitter/wander generation capability 8 8.6 Generation accuracy . 9 9 Jitter measurement function 11 9.1 Reference timing signal 11 9.2 Measurement capabilities . 11 9.3
18、Measurement bandwidths. 13 9.4 Measurement accuracy . 15 9.5 Jitter transfer measurement accuracy . 18 9.6 Additional facilities 18 10 Wander measurement function. 18 10.1 Reference timing signal 18 10.2 Measurement of TIE (Time Interval Error) 18 10.3 Measurement of transient TIE (Time Interval Err
19、or) . 19 10.4 Measurement of MTIE (Maximum Time Interval Error). 20 10.5 Measurement of TDEV (Time Deviation) . 22 10.6 Measurement of frequency offset. 23 10.7 Measurement of frequency drift rate 24 11 TDEV wander noise generation function . 26 iv ITU-T Rec. O.172 (04/2005) Page 12 MTIE wander nois
20、e generation function 26 13 Operating environment . 26 Annex A Structured test signals for the measurement of jitter. 27 A.1 Introduction 27 A.2 Test signal structure for STM-N signals 27 A.3 Test signal structure for concatenated STM-N signals. 28 Annex B Definition of band-limited peak-to-peak pha
21、se slope error. 29 Annex C MTIE upper limit for TDEV wander noise . 30 Appendix I Guidelines concerning the measurement of jitter in SDH systems 32 Appendix II Guidelines concerning the measurement of wander in SDH systems 33 II.1 Wander measurements 33 II.2 Clock stability measurements. 34 Appendix
22、 III Guidelines concerning the generation of pointer test sequences. 35 Appendix IV Total jitter measurement function response 36 IV.1 Introduction 36 IV.2 Measurement filter parameters . 36 IV.3 Mask limits for high-pass measurement filter response. 36 Appendix V Verification of MTIE and TDEV calcu
23、lation algorithms 38 V.1 TIE noise source functional description. 38 V.2 First example of TIE noise generator . 38 V.3 Second example of TIE noise generator. 38 Appendix VI MTIE generation evaluation . 39 Appendix VII Method for verification of measurement result accuracy and intrinsic fixed error .
24、 42 VII.1 Verification description and application 42 VII.2 System implementation 42 VII.3 Results and interpretation. 45 Appendix VIII Method for characterization of transmit intrinsic jitter 47 VIII.1 Verification description and application 47 VIII.2 Method 47 VIII.3 Diagnostic test pattern 49 VI
25、II.4 Calculation of peak-to-peak value from the probability distribution function. 50 ITU-T Rec. O.172 (04/2005) v Introduction The timing and synchronization performance of SDH networks and SDH network equipment elements is specified in a number of ITU-T Recommendations, using jitter and wander par
26、ameters. This Recommendation specifies the various characteristics of jitter/wander measuring equipment, which are needed in order to support the requirements of these ITU-T Recommendations and to perform other test and measuring tasks. This Recommendation has been developed to ensure maximum compat
27、ibility with the relevant SDH network and equipment measurement requirements, whilst maintaining backwards compatibility with the associated PDH test equipment requirements of ITU-T Rec. O.171 18 where possible. ITU-T Rec. O.172 (04/2005) 1 ITU-T Recommendation O.172 Jitter and wander measuring equi
28、pment for digital systems which are based on the synchronous digital hierarchy (SDH) 1 Scope This Recommendation specifies test instrumentation that is used to generate and measure timing jitter and synchronization wander in digital systems based on the Synchronous Digital Hierarchy (SDH). This Reco
29、mmendation also specifies requirements for the measurement of SDH tributaries operating at PDH bit rates. The test instrumentation consists principally of a jitter/wander measurement function and a jitter/wander generation function. Measurements can be performed at the physical layer of SDH systems.
30、 A bit-error rate test set may also be required for certain types of measurements; this may be part of the same instrumentation or it may be physically separate. Test instrumentation for the generation and measurement of jitter and wander in digital systems based on the Plesiochronous Digital Hierar
31、chy (PDH) is specified in ITU-T Rec. O.171 18. It is recommended that ITU-T Recs G.783 6, G.812 9, G.813 10, G.825 13 and G.798 15 be read in conjunction with this Recommendation. 2 References 2.1 Normative references The following ITU-T Recommendations and other references contain provisions which,
32、 through reference in this text, constitute provisions of this Recommendation. 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 appl
33、ying the most recent edition of the Recommendations and other references 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. 1 ITU
34、-T Recommendation G.691 (2003), Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers. 2 ITU-T Recommendation G.693 (2005), Optical interfaces for intra-office systems. 3 ITU-T Recommendation G.703 (2001), Physical/electrical characteristics of hierarchical digit
35、al interfaces. 4 ITU-T Recommendation G.707/Y.1322 (2003), Network node interface for the synchronous digital hierarchy (SDH). 5 ITU-T Recommendation G.772 (1993), Protected monitoring points provided on digital transmission systems. 6 ITU-T Recommendation G.783 (2004), Characteristics of synchronou
36、s digital hierarchy (SDH) equipment functional blocks. 7 ITU-T Recommendation G.810 (1996), Definitions and terminology for synchronization networks. 8 ITU-T Recommendation G.811 (1997), Timing characteristics of primary reference clocks. 2 ITU-T Rec. O.172 (04/2005) 9 ITU-T Recommendation G.812 (20
37、04), Timing requirements of slave clocks suitable for use as node clocks in synchronization networks. 10 ITU-T Recommendation G.813 (2003), Timing characteristics of SDH equipment slave clocks (SEC). 11 ITU-T Recommendation G.823 (2000), The control of jitter and wander within digital networks which
38、 are based on the 2048 kbit/s hierarchy. 12 ITU-T Recommendation G.824 (2000), The control of jitter and wander within digital networks which are based on the 1544 kbit/s hierarchy. 13 ITU-T Recommendation G.825 (2000), The control of jitter and wander within digital networks which are based on the
39、synchronous digital hierarchy (SDH). 14 ITU-T Recommendation G.957 (1999), Optical interfaces for equipments and systems relating to the synchronous digital hierarchy. 15 ITU-T Recommendation G.798 (2004), Characteristics of optical transport network hierarchy equipment functional blocks. 16 ITU-T R
40、ecommendation O.3 (1992), Climatic conditions and relevant tests for measuring equipment. 17 ITU-T Recommendation O.150 (1996), General requirements for instrumentation for performance measurements on digital transmission equipment. 18 ITU-T Recommendation O.171 (1997), Timing jitter and wander meas
41、uring equipment for digital systems which are based on the plesiochronous digital hierarchy (PDH). 19 ITU-T Recommendation O.181 (2002), Equipment to assess error performance on STM-N interfaces. 20 ITU-R Recommendation F.750-4 (2000), Architectures and functional aspects of radio-relay systems for
42、synchronous digital hierarchy (SDH)-based networks. 2.2 Informative references 21 ANSI T1.105.03-2003, Synchronous Optical Network (SONET) Jitter and Wander at Network and Equipment Interfaces. 22 ANSI T1.105.06-2002, Synchronous Optical Network (SONET): Physical Layer Specifications. 3 Definitions
43、For the purposes of this Recommendation, the following definitions apply (refer to ITU-T Rec. G.810 7): 3.1 (timing) jitter: The short-term variations of the significant instances of a digital signal from their ideal positions in time (where “short-term“ implies that these variations are of frequenc
44、y greater than or equal to 10 Hz). 3.2 wander: The long-term variations of the significant instances of a digital signal from their ideal position in time (where “long-term“ implies that these variations are of frequency less than 10 Hz). 3.3 time interval error (function): The difference between th
45、e measure of a time interval as provided by a clock and the measure of that same time interval as provided by a reference clock. _ T1 standards are maintained since November 2003 by ATIS. ITU-T Rec. O.172 (04/2005) 3 It may be useful to note that ITU-T Rec. G.810 7 provides additional definitions an
46、d abbreviations used in timing and synchronization Recommendations. It also provides background information on the need to limit phase variation and the impairments on digital systems. 4 Abbreviations This Recommendation uses the following abbreviations: AU-n Administrative Unit, level n CMI Coded M
47、ark Inversion MTIE Maximum Time Interval Error NRZ Non Return to Zero PDH Plesiochronous Digital Hierarchy PJE Pointer Justification Event PLL Phase-Locked Loop ppm parts per million PRBS Pseudo Random Binary Sequence RMS Root-Mean-Square SDH Synchronous Digital Hierarchy STM-N Synchronous Transport
48、 Module, level N TDEV Time Deviation TIE Time Interval Error TSS Test Signal Structure TU-m Tributary Unit, level m UI Unit Interval UIpp Unit Interval, peak-to-peak 5 Conventions For the purposes of this Recommendation, the following conventions are adopted: a) Particular interface signals used are
49、 denoted either by their standardized signal formats, e.g., STM-1 or by their bit rate, e.g., 139 264 kbit/s. The default physical format of SDH interfaces is considered to be optical and the default physical format of PDH interfaces is considered to be electrical. b) Where the electrical form of an SDH interface is specifically used in this Recommendation, the interface is denoted by “e“, e.g., STM-1e (refer also to clause 7). c) Particular interface signals used may be categor
