1、 STD-ITU-T RECMN OsL71-ENGL 1997 I 48b2591 Ob37592 T71 D INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 0.171 SERIES O: SPECIFICATIONS OF MEASURING EQUIPMENT Equipment for the measurement of digital and analog ue/d ig i ta I para meters (04/97) Timing jit
2、ter and wander measuring equipment for digital systems which are based on the pl es i oc h ron ous dig i tal h i era rc h y (P D H) ITU-T Recommendation O. 171 (Previously CCITT Recommendation) STD-ITU-T RECMN 0.17L-ENGL 1777 D 48b2571 Ob37573 708 9 ITU-T O-SERIES RECOMMENDATIONS SPECIFICATIONS OF M
3、EASURING EQUIPMENT General o. 1-0.9 Maintenance access Automatic and semi-automatic measuring systems Equipment for the measurement of analogue parameters Equipment for the surement of digit nd anaiogueidigit S 130-0.1 99 o. 1 0-0. I 9 0.20-0.39 0.40-0.129 For further details, please refir to ITU-T
4、List of Recommendations. STDaITU-T RECMN 0-17L-ENGL L977 LiBb259L Ob37594 BL(L( ITU-T RECOMMENDATION 0.171 TIMING JITTER AND WANDER MEASURING EQUIPMENT FOR DIGITAL SYSTEMS WHICH ARE BASED ON THE PLESIOCHRONOUS DIGITAL HIERARCHY (PDH) Summary The requirements for the characteristics of the jitter and
5、 wander measuring equipment which are described below must be adhered to in order to ensure compatibility between equipment produced by different manufacturers. While requirements are given for the equipment, the realization of the equipment configuration is not covered and should be given careful c
6、onsideration by the designer and user. In particular, it is not required that all features listed below shall be provided in one piece of equipment. Users may select those functions which correspond best to their applications. Source ITU-T Recommendation O. 17 1 was revised by ITU-T Study Group 4 (1
7、 997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 19th of April 1997. Keywords Jitter generation, jitter measurements, jitter transfer function, output jitter, tolerable input jitter, wander generation, wander measurements. STD-ITU-T RECMN O-LiL-ENGL 1497 M Li8b259L Ob3757
8、5 780 W FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff qu
9、estions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Reco
10、mmendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within IT-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and
11、 IEC. . NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Reco
12、mmendation may involve the use of a claimed Intellectual Property Right. The IT takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of
13、 approval of this Recommendation, the ITU hadhad 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 are therefore strongly urged to cons
14、ult the TSB patent database. O ITU 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation 0.171 (04/97) STD-ITU-T RE
15、CMN 0.171-ENGL 1797 LiAb2571 Ob3757b b17 = 1 2 2.1 2.2 3 4 5 6 6.1 6.2 7 7.1 7.2 7.3 8 8.1 8.2 8.3 8.4 8.5 CONTENTS Page Scope References Normative references Bibliographical references Definitions Abbreviations . Block diagram Interfaces Electrical interfaces Interface impedances Test signal source
16、 . Modulation source Clock generator 7.2.1 Accuracy ofthe clock generator Test sequence generator 7.3.1 Test sequences . 7.3.2 Generation errors . Jitter measuring circuit . Input sensitivity of the electrical interfaces Jitter measurement ranges 8.2.1 Measurement of peak-to-peak jitter 8.2.2 Select
17、able threshold . 8.2.3 Measurement of r.m.s. jitter Measurement bandwidths . 8.3.1 Frequency response ofjitter measuring circuit and filters Measurement accuracy . 8.4.1 General 8.4.2 Fixed error . 8.4.3 Error at other frequencies 8.4.4 Test sequence dependent error 8.4.5 Pulse shape at the measurem
18、ent access point Additional facilities 8.5.1 Analogue output 8.5.2 Reference timing signal . Recommendation O . 17 1 (04/97) 2 2 2 3 3 4 6 6 7 7 7 8 8 8 9 9 9 9 11 11 11 11 11 . 111 9 Operating environment . Appendix I . Guidelines concerning the measurement of jitter I . 1 1.2 1.3 1.4 1.5 1.6 Defin
19、itions and causes of jitter . Test environment 1.2.1 Controlled test sequences Pulse shape and cable characteristics Secondary test environment parameters Glossary of test configuration functional block components . 1.2.2 Bit rate . 1.2.3 1.2.4 Jitter tolerance measurement 1.4.1 Actual tolerance . 1
20、.4.2 Jitter tolerance template compliance . Jitter transfer characteristic measurement 1.5.1 Linear processes Output jitter measurement 1.6.2 Controlled test sequences 1.6.1 Live traffic . Appendix II . Guidelines concerning the measurement of wander . II . 1 Wander measurements II . 1.1 Wander meas
21、urement configurations - General considerations . II . 1.2 Synchronized wander measurements II . 1.3 Non-synchronized wander measurements . 11.2 Clock stability measurements . Quantities to be measured 11.3 11.3.1 Time deviation . 11.3.2 Maximum time interval error 11.3.3 Allan deviation 11.4 Extern
22、al reference . Page 11 11 11 13 13 14 14 14 15 16 16 19 19 19 23 23 24 24 25 25 25 25 26 26 26 27 27 27 iv Recommendation 0.171 (04/97) Recommendation 0.171 TIMING JITTER AND WANDER MEASURING EQUIPMENT FOR DIGITAL SYSTEMS WHICH ARE BASED ON THE PLESIOCHRONOUS DIGITAL HIERARCHY (PDH) (Geneva, 1980; a
23、mended Malaga-Torremolinos, 1984; Melbourne, I988; revised in 1997) 1 Scope The instrumentation specified in this Recommendation will be used to measure timing jitter and wander on digital systems based on the Plesiochronous Digital Hierarchy (PDH). The instrumentation consists of a jitter measuring
24、 circuit and a test signal source. Measurements can be performed at the physical layer of PDH systems. An error-ratio meter may also be required for certain types of measurements. Instrumentation for the measurement of jitter and wander on digital systems based on the Synchronous Digital Hierarchy (
25、SDH) is specified in a separate O-Series Recommendation. It is recommended that Recommendations G.823 7 and G.824 8 be read in conjunction with this Recommendation. 2 References 2.1 Normative references The following ITU-T Recommendations and other references contain provisions which, through refere
26、nce in this text, constitute provisions of this Recommendation. All Recommendations are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations listed below. A list of the currently valid
27、 ITU-T Recommendations is regularly published. ITU-T Recommendation G.701 (1 993), Vocabulary of digital transmission and multiplexing, and Pulse Code Modulation (PCM) terms. CCITT Recommendation G.703 (1 99 i), Physical/electrical characteristics of hierarchical digital interfaces. ITU-T Recommenda
28、tion G.772 (1 993), Protected monitoring points provided on digital transmission systems. ITU-T Recommendation G.8 1 O (1 996), Definitions and terminology for synchronization networks. CCITT Recommendation G.811 (1988), Timing requirements at the outputs of primary reference clocks suitable for ple
29、siochronous operation of international digital links. CCITT Recommendation G.8 12 (1 988), Timing requirements at the outputs of slave clocks suitable for plesiochronous operation of international digital links. ITU-T Recommendation G.823 (1993), The control of jitter and wander within digital netwo
30、rks which are based on the 2048 kbit/s hierarchy. ITU-T Recommendation G.824 (1993), The control of jitter and wander within digital networks which are based on the 1544 kbit/s hierarchy. Recommendation 0.171 (04/97) 1 CCITT Recommendation 0.3 (1 992), Climatic conditions and relevant tests for meas
31、uring equipment. ITU-T Recommendation O. 150 (1 996), General requirements for instrumentation for performance measurements on digital transmission equipment. Bibliographical references ANSI Standard T1.102- 1993, Digital hierarchy - Electrical interfaces. HUCKETT (P.): Performance Evaluation in an
32、ISDN - Digital Transmission Impairments, Radio and Electronic Engineer, Vol. 54, No. 2, February 1984. TRISCHITTA (P.R.): Jitter Accumulation in Fibre Optic Systems, Rutgers, The State University of New Jersey, May 1986. TRISCHITTA (P.R.), SANUTTI (P.): The Jitter Tolerance of Fibre Optic Regenerato
33、rs, IEEE Transactions on Communications, Vol: 35, No. 12, December 1987. Definitions This Recommendation defines the following terms (see Recommendation G.8 1 O 4): 3.1 (timing) jitter: The short-term variations of the significant instances of a digital signal from their ideal positions in time (whe
34、re short-tem implies these variations are of frequency 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). 4 Abbrevia
35、tions This Recommendation uses the following abbreviations. AMI Alternate Mark Inversion MTIE Maximum Time Interval Error NRZ Non Return to Zero PDH Plesiochronous Digital Hierarchy SDH Synchronous Digital Hierarchy TDEV Time Deviation TIE Time Interval Error u1 Unit Interval 5 Block diagram Figure
36、1 shows the block diagram of the instrumentation in general form. The figure does not describe a specific implementation. 2 Recommendation 0.171 (04/97) - STD.ITU-T RECMN 0-17L-ENGL 1997 m Lib259L Ilb37b00 978 Test signal source :- 4 External modulation a Clock generator - Modulated clock f !I t i 1
37、 Testsequence/ ; frame generator Test I f Analogue seouence I I l output Jitter and wander +?.-I G.703 Unit under test measuring circuit interface 1 I interface u TO4O960-96 NOTE -The modulation source, to test to relevant G-Series Recommendations, may be provided within the clock generator and/or t
38、est sequence generator, or it may be provided separately. Figure U0.171- Simplified block diagram for measuring timing jitter and wander 6 Interfaces 6.1 Electrical interfaces The instrumentation shall be capabie of operating at one or more of the following bit rates and corresponding interface char
39、acteristics as described in the appropriate clauses of Recommendation G.703 2. However, for all bit rates the signal applied to the input of the jitter measuring circuit should be a nominal rectangular pulse. Other signal shapes may produce inter- symbol interference - which cannot be corrected by s
40、imple line equalization - thus affecting measurement accuracy. a) 64 kbit/s;i f, 32 064 kbits; b) 1544 kbits; g) 44 736 kbits; c) 6 312 kbit/s; h) 34 368 kbit/s; d) 2 048 kbits; i) 139 264 kbits. e) 8 448 kbit/s; As an option, the jitter measuring circuit shall be capable of measuring jitter at a cl
41、ock output port when such an access is provided on digital equipment. References to 64 kbits relate to the Co-directional interface. Recommendation 0.171 (04/97) 3 6.2 Interface impedances The jitter measuring circuit and signal source shall have a return loss as specified in Table 12 under the cond
42、itions listed in the Table. Bit rate (kbi t/s) 7 Return loss Test conditions (dB) 8 448 120 R, non-reactive 1544 100 !2, non-reactive 2 12 75 R, non-reactive 2 18 2 14 75/120/130 R, non-reactive 6 312 75/110 a, non-reactive 34 368 2 12 75 R, non-reactive 2 18 2 14 I 32064 I 220 I 75 Q,non-reactive 1
43、39 264 2 15 75 R, non-reactive I 44 736 I 220 I 75 SZ, non-reactive Test signal source 3 kHz to 6.4 kHz 6.4 to 128 kHz 128 to 192 kHz 20 kHz to 1.6 MHz 51 to 102 kHz 102 to 2 048 kHz 2 048 to 3 072 kHz 100 kHz to 6.5 MHz 21 1 to 422 kHz 422 to 8 448 kHz 8 448 to 12 672 kHz 500 kHz to 40 MHz 860 to 1
44、72 040 kHz 1 720 to 34 368 kHz 34 368 to 51 550 kHz 500 kHz to 50 MHz 7 MHz to 210 MHz Tests of digital equipment may be made with either a jittered or a non-jittered digital signal. This will require the test sequence generator, frame generator, clock generator and modulation source shown in Figure
45、 1. 7.1 Modulation source The modulation source, required to perform tests in conformance with relevant Recommendations, may be provided within the clock generator and/or test sequence generator or it may be provided separately. In this Recommendation it is assumed that the modulation source is sinu
46、soidal. However, random stimuli may be required for certain tests. Details need to be studied. 7.2 Clock generator It shall be possible to phase modulate the clock generator from the modulation source and to indicate the peak-to-peak phase deviation of the modulated signal. The generated peak-to-pea
47、k jitter and the modulating frequencies shall meet the minimum requirements of Figure 2 and Table 2. In the case of 1544 kbit/s, the test signal source shall have the followingreturn loss: 20 kHz to 500 kHz 2 14 dB and 500 kHz to 1.6 MHz 2 16 dB. 4 Recommendation 0.171 (04/97) STD-ITU-T RECMN 0-17L-
48、ENGL 2997 R LIBb259L Ob37b02 740 9 44 736 10 0.5 139264 3 O00 20 10 0.5 a) The modulating input sensitivity of the clock generator shall be at least: 1 volt peak-to-peak into 75 L2 for bit rates up to and including 139 264 kbit/s. The minimum output of the modulated clock signal and the external tim
49、ing reference signal shall be 1 volt peak-to-peak into 75 Q. 2 5000 100k 400k a) a) 50 100 500 10k 3 500k L e A f” f, fil fi0 f9 f* f, f2 f3 f4 Frequency (log scale) TO406970-96 Figure U0.171- Generated jitter amplitude versus jitter frequency Recommendation 0.171 (04/97) 5 7.2.1 The deviation of the internal clock signal from the nominal value shall be less than 1 O-. As an option, the clock generator may provide frequency offset of sufficient magnitude to facilitate testing across the equipment clock tolerance range, e.g. 210 ppm to IT100 ppm, as defined for
