1、STD-ETSI PRETS 300 462-b-ENGL 1998 3400855 0275328 382 m LUROPEAN T 1 ELECOMMUNICATION STANDARD FINAL DRAFT pr ETS 300 462-6 March 1998 _ Source: TM Reference: DWTM-03017-6 ICs: 33.020 Key words: Synchronization, transmission, SDH Transmission and Multiplexing (TM); Generic requirements for synchron
2、ization networks; Part 6: Timing characteristics of primary reference clocks ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.400: c=fr, a=atla
3、s, p=etsi, s=secretariat - Internet: secretariatQetsi.fr Tel.: +33 4 92 94 42 O0 - Fax: +33 4 93 65 47 16 _ Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. O European Teleco
4、mmunications Standards Institute 1998. All mhts reserved. COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling Services STD-ETSI PRETS 300 4,bZ-b-ENGL 1778 9 3400855 0275327 2L7 Page 2 Final draft prETS 300 462-6: March 1998 Whilst every care has been taken in th
5、e preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title page. COPYRIGHT European Telecommunications Standards I
6、nstituteLicensed by Information Handling ServicesSTD-ETSI PRETS 300 YbZ-b-ENGL 1998 = 3400855 0275330 T30 Page 3 Final draft prETS 300 462-6: March 1998 Contents Foreword . . 5 1 Scope . 7 2 Normative references 7 3 Definitions and abbreviations _. 8 4 Frequency accuracy 8 5 Noise generation . 8 5.1
7、 Wander . 8 5.2 Jitter 9 6 Phase discontinuity 9 7 Degradation of the performance of a PRC 10 8 Interfaces . . 10 Annex A (informative): Bibliography . 11 History . 12 COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling ServicesSTDOETSI PRETS 300 4b2-b-ENGL 3998
8、 m 3400855 0275333 977 m Page 5 Final draft prETS 300 462-6: March 1998 Foreword This final draft European Telecommunication Standard (ETS) has been produced by the Transmission and Multiplexing (TM) Technical Committee of the European Telecommunications Standards Institute (ETSI), and is now submit
9、ted for the Voting phase of the ETSI standards approval procedure. This ETS has been produced in order to provide requirements for synchronization networks that are compatible with the performance requirements for digital networks. It is one of a family of ETSs covering various aspects of synchroniz
10、ation networks: This ETS consists of 6 parts as follows: Part 1: “Definitions and terminology for synchronization networks “ Part 2: “Synchronization network architecture I. Part 3: “The control of jitter and wander within synchronization networks “. Part 4: “Timing characteristics of slave clocks s
11、uitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment . Part 5: “Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy (SDH) equipment“. Part 6: “Timing characteristics of primary refere
12、nce clocks “. Proposed transposition dates Date of latest announcement of this ETS (doa): 3 months after ETSI publication Date of latest publication of new National Standard or endorsement of this ETS (dop/e): 6 months after doa 1 I Date of withdrawal of any conflicting National Standard (dow): 6 mo
13、nths after doa Pi-evioiis page is blaiik COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling ServicesSTD.ETS1 PRETS 300 462-b-ENGL 1998 3400855 0275332 803 Page 7 Final draft prETS 300 462-6: March 1998 1 Scope This European Telecommunication Standard (ETS) outl
14、ines requirements for Primary Reference Clocks (PRCs) suitable for synchronization supply to digital networks. NOTE: The requirements in this ETS apply under environmental conditions according to one of the environmental classes defined in ETS 300 O19 l, unless stated otherwise. The manufacturer wil
15、l need to specify to which specific environmental class an equipment belongs. A typical PRC provides the reference signal for the timing or synchronization of other clocks within a network or section of a network. The long-term accuracy of the PRC should be maintained at 1 part in 10“ or better with
16、 verification to Universal Coiirdinated Time (UTC). The long-term accuracy of 1 part in 10 l1 or better is adequate when a single PRC provides the reference synchronization signal to all other clocks within a network (synchronous mode of operation). in the pseudo-synchronous mode, .e. not all clocks
17、 in the network have timing traceable to the same PRC, the long term accuracy requirement is dependent on the number of PRCs in that network. When more than one PRC is used in a network, a statistical approach is needed to determine the long-term accuracy requirement of each PRC in that network. 2 N
18、ormative references This ETS incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references subsequent amendments to, or revisions of, any of th
19、ese publications apply to this ETS only when incorporated in it by amendments or revisions. For undated references the latest edition of the publication referred to applies. 31 41 51 ETS 300 O1 9 (1 994): “Equipment Engineering (EE); Environmental conditions and environmental tests for telecommunica
20、tions equipment “. ETS 300 462-1 (1996): “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 1 : Definitions and terminology of synchronization networks I. ETS 300 462-2 (1 996): “Transmission and Multiplexing (TM); Generic requirements for synchronization ne
21、tworks; Part 2: Synchronization network architecture“. ETS 300 462-3 (1 997): “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 3: The control of jitter and wander within synchronization networks “. ETS 300 462-4 (1 997): “Transmission and Multiplexing (TM)
22、; Generic requirements for synchronization networks: Part 4: Timing characteristics of slave clocks suitable for operation in synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment *. ETS 300 462-5 (1 996): “Transmission and Multiplexing (T
23、M): Generic requirements for synchronization networks; Part 5: Timing characteristics of slave clocks suitable for Synchronous Digital Hierarchy (SDH) equipment “. ITU-T Recommendation G.703 (1 991): “Physical/electrical characteristics of hierarchical digital interfacesm, Previous page is blank COP
24、YRIGHT European Telecommunications Standards InstituteLicensed by Information Handling Services STD-ETSI PRETS 300 4b2-b-ENGL 1998 = 3400855 0275333 74T Page 8 Final draft prETS 300 462-6: March 1998 3 Definitions and abbreviations For the purpose of this ETS, the definitions of the terminology and
25、the abbreviations of ETS 300 462-1 2 apply. 4 Frequency accuracy The maximum allowable fractional frequency offset for observation times greater than one week is 1 part in lo1, over all applicable environmental conditions as defined in ETS 300 O19 l. 5 Noise generation The noise generation of a PRC
26、clock represents the amount of phase noise produced at its output. A suitable reference, for practical testing purposes, implies a performance level that is more stable than the output requirements. The ability of the clock to limit this noise is described by its frequency stability. The measures Ma
27、ximum Time Interval Error (MTIE) and Time Deviation (TDEV) are useful for characterization of noise generation performance. It is important for consistency in measuring MTIE and TDEV parameters that an anti-aliasing filter, maximum sampling time and measurement interval are specified. These are give
28、n in annex A of ETS 300 462-3 4. 5.1 Wander The wander, expressed in MTIE, measured using the independent clock configuration defined in figure 2.A of ETS 300 462-1 2 should have the following limits: (1 0-52 + 0,29) PS for z 1 o00 s The resultant requirements are shown in figure 1. 1 O00 MTIE loo m
29、icro- 10 seconds 1 0.1 0.01 ! 0.01 1 100 10000 1000000 1E+08 observation period (seconds) Figure 1: MTIE as a function of an observation (integration) period z COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling ServicesSTD.ETSI PRETS 300 4b2-b-ENGL 1998 9 34008
30、55 0275334 b8b Page 9 Final draft prETS 300 462-6: March 1998 The wander, expressed in TDEV, measured using the independent clock configuration defined in figure 2.A of ETS 300 462-1 2 should have the following limits: TDEV: 3 ns for 0.1 SZl 100s 0,03 7 ns for 100 s 21 1 O00 s 30 ns for 1 O00 s z 10
31、 O00 s The resultant requirements are shown in figure 2. 30 10 3 1 I 091 1 10 1 O0 1 O00 10 O00 observation period (seconds) Figure 2: TDEV as a function of an observation (integration) period z 5.2 Jitter While most specifications in this ETS are independent on the output interface at which they ar
32、e measured, this is not the case for jitter production; jitter generation specifications shall utilize existing specifications that are currently specified differently for different interface rates. These requirements are stated separately for the interfaces identified in clause 8. To be consistent
33、with other jitter requirements the specifications are in Uipp. The Unit interval (Ui) equals one cycle of the clock signai or, in case of a digital interface signal, the reciprocal of its bitrate. The intrinsic jitter at 2 048 kHz and 2 048 kbit/s output interfaces as measured over a 60 second inter
34、val shall not exceed 0,05 Ulpp when measured through a single pole band-pass filter with corner frequencies at 20 Hz and 100 kHz. 6 Phase discontinuity PRCs need a very high reliability and are likely to include replication of the equipment in order to ensure the continuity of the output. However, a
35、ny phase discontinuity, due to internal operations within the clock, should only result in a lengthening or shortening of the timing signal interval and shall not, at the clock output, cause a phase discontinuity in excess of 1/8 Ui (this refers to output signals at 2 048 kbis or 2 048 kHz). COPYRIG
36、HT European Telecommunications Standards InstituteLicensed by Information Handling ServicesSTD-ETSI PRETS 300 4b2-b-ENGL 1998 W 3400855 0275335 512 Page 10 Final draft prETS 300 462-6: March 1998 7 Degradation of the performance of a PRC If redundancy is applied and a clock frequency departs signifi
37、cantly from its nominal value, this should be detected and switching to an undegraded oscillator should then be effected. This switching should be accomplished before the MTIE or TDEV specification is exceeded. 8 Interfaces The requirements in this ETS are related to reference points internal to the
38、 equipment or Network Element (NE) in which the PRC is embedded and are therefore not necessarily available for measurement or analysis by the user. Therefore the performance of the PRC is not specified at these internal reference points, but rather at the external interfaces of the equipment. The o
39、utput interfaces specified for the equipment in which the PRC clock may be contained are: - 2 048 kHz interfaces according to ITU-T Recommendation G.703 7, section 10 with additional jitter and wander requirements as specified herein; - 2 048 kbitls interfaces according to ITU-T Recommendation G.703
40、 7, section 6 with additional jitter and wander requirements as specified herein; - other interfaces (such as sine wave 8 kHz to 5 MHz) are for further study. COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling ServicesSTD.ETS1 PRETS 300 462-b-ENGL 1998 = 340085
41、5 0275336 459 Page 11 Final draft prETS 300 462-6: March 1998 Annex A (informative): Bibliography - ITU-T Recommendation G.810 (1996): “Definitions and terminology for synchronization networks “. - ITU-T Recommendation G.811 (1988): “Timing requirements at the outputs of primary reference clocks sui
42、table for plesiochronous operation of international digital links “. - ITU-T Recommendation G.812 (1988): “Timing requirements at the outputs of slave clocks suitable for plesiochronous operation of international digital links “. - ITU-T Recommendation G.813 (1996): “Timing Characteristics of SDH Eq
43、uipment Slave Clocks (SEC)“. COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling ServicesSTD.ETSI PRETS 300 462-b-ENGL 1998 3400855 0275337 395 Page 12 Final draft prETS 300 462-6: March 1998 January 1997 March 1998 History Document history Public Enquiry PE 9722: 1997-01-31 to 1997-05-30 Vote V 9820: 1998-03-1 7 to 1998-05-1 5 COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling Services
