1、STDmETSI PRETS 300 LibZ-b-ENGL 1777 3q00855 0158102 220 DRAF pr ETS 300 462-6 January 1997 Source: ETSI TC-TM Reference: DE/TM-03017-6 ICs: 33.020 Key words: Synchronization, transmission, SDH Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 6: Timing chara
2、cteristics 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=atlas, p=etsi, s=secretarat - Internet: se
3、cretariatetsi.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 ali media. Q European Telecommunications Standards institute 1997. Ali
4、 rights reserved. STD*ETSI PRETS 300 VbZ-b-ENGL 1777 W 3400855 0158103 Lb7 W Page 2 Draft prETS 300 462-6: January 1997 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its
5、accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title page. STD-ETSI PRETS 300 4bZ-b-ENGL 1777 3400855 OL58LOLi UT3 Page 3 Draft prETS 300 462-6: January 1997 Contents Foreword . 5 1 Scope 7 2 Nomative references 7 3 Definitions and abbreviations 7 4
6、Frequency accuracy 7 5 Noise generation . 8 5.1 Wander 8 5.2 Jitter . 9 6 Phase discontinuity 9 7 Degradation of the performance of a PRC 9 8 Interfaces . 10 History 11 STD-ETSI PRETS 300 4bZ-b-ENGL 1777 3400855 1158105 T3T Page 4 Draft prETS 300 462-6: January 1997 Blank page STD*ETSI PRETS 300 4b2
7、-b-ENGL 1777 3400855 O1581Ob 77b Page 5 Draft prETS 300 462-6: January 1997 Foreword This draft European Telecommunication Standard (EIS) has been produced by the Transmission and Multiplexing (TM) Technical Committee of the European Telecommunication Standards Institute (ETSI), and is now submitted
8、 for the Public Enquiry 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 synch
9、ronization networks: This ETS consists of 6 parts as follows: Part 1: “Definitions and terminology for synchronization networks“ (ETS 300 462-1 2); Part 2: “Synchronization network architecture“ (ETS 300 462-2 3); Part 3: Part 4: Part 5: “The control of jitter and wander within synchronization netwo
10、rks“ (ETS 300 462-3 4); “Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment“ (ETS 300 462-4 Ei); “Timing characteristics of slave clocks suitable for operation in Synchronous Digital H
11、ierarchy (SDH) equipment“ (ETS 300 462-5 SI); Pari 6: “Timing characteristics of primary reference 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/
12、e): 6 months after doa Date of withdrawal of any conflicting National Standard (dow): 6 months after doa I STD-ETSI PRETS 300 4bZ-b-ENGL 1777 3400855 0158107 802 Page 6 Draft prETS 300 4628: January 1997 Blank page STD-ETSI PRETS 300 Lib2-b-ENGL 1997 3400855 015L08 7Li7 Page 7 Draft prETS 300 462-6:
13、 January 1997 I Scope This European Telecommunication Standard (ETS) outlines requirements for Primary Reference Clucks (PRCs) suitable for synchronization supply to digital networks. These requirements apply under the normal environmental conditions specified for digital equipment. A typical PRC pr
14、ovides 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 verification to Universal Co-ordinated Time (UTC). The long-term accuracy of 1 part in 10“ or
15、 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 in the network have timing traceable to the same PRC, the long term accuracy requirement is dep
16、endent 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 Normative references This ETC incorporates by dated or undated reference, provisions from other
17、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 these publications apply to this ETS only when incorporated in it by amendments or revisions. For
18、 undated references the latest edition of the publication referred to applies. ETS 300 O1 9: “Equipment Engineering (EE); Environmental conditions and environmental tests for telecommunications equipment“. prETS 300 462-1 : “Transmission and Multiplexing (TM); Generic requirements for synchronizatio
19、n networks; Part 1 : Definitions and terminology of synchronization networks“. ETS 300 462-2: “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 2: Synchronization network architecture“. prETS 300 462-3: “Transmission and Multiplexing (TM); Generic requireme
20、nts for synchronization networks; Part 3: The control of jitter and wander within synchronization networks“. prETS 300 462-4: “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 4: Timing characteristics of slave clocks suitable for synchronization supply to
21、Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment“. ETC 300 462-5: “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 5: Timing characteristics of slave clocks suitable for Synchronous Digital Hierarchy (SDH) equipment“
22、. ITU-T Recommendation G.703: “Physicaelectrical characteristics of hierarchical digital interfaces“. 3 Definitions and abbreviations The definitions of the terminology and the abbreviations used in this ETS are described in ETS 300 462-1 2. 4 Frequency accuracy The maximum allowable fractional freq
23、uency offset for observation times greater than one week is 1 pari in lo, over all applicable environmental conditions as defined in ETS 300 O1 9 l. STD-ETSI PRETS 300 4bZ-b-ENGL 3997 = 3400855 0358307 b85 M Page 8 Draft prETS 300 462-6: January 1997 5 Noise generation The noise generation of a PRC
24、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
25、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
26、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: MTIE: 0,275 x 1092 + 0,025 ps for o,i 1000s The resultant requirements are shown in figure 1. MTIE
27、 micro- seconds 1000 - - 100 - . 10 7 - 1 t- 0,l :- - 0,Ol 1 1 O0 10000 1000000 1E+08 observation period (seconds) Figure 1: MTIE as a function of an observation (integration) period 2 The wander, expressed in TDEV, measured using the independent clock configuration defined in figure 2.A of ETS 300
28、462-1 2 should have the following limits: TDEV: 3 ns for O,I z 5100s z Il 000s .c T 40 000s 0,03znsfor 100 30 nsfor 1 O00 1000 TDEV nano- seconds 100 30 10 3 1 I 6 Phase discontinuity PRCs need a very high reliability and are likely to include replication of the equipment in order to ensure the cont
29、inuity of the output. However, any 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
30、 048 kbits or 2 048 kHz). r-r-r-l r- _- - I I I I I l I I l I I I l l I -L-C-L-b- I I l l I l I i i I I I l l I I I I I l I l l l l I l I - _- - I 7 Degradation of the performance of a PRC If redundancy is applied and a clock frequency departs significantly from its nominal value, this should be det
31、ected and switching to an undegraded oscillator should then be effected. This switching should be accomplished before the MTIE or TDEV specification is exceeded. I STD-ETSI PRETS 300 4b2-b-ENGL 1777 H 3400855 0358333 233 = Page 10 Draft prETS 300 462-6: January 1997 a Interfaces The requirements in
32、this ETS are related to reference points internal to the 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 r
33、ather at the external interfaces of the equipment. The output 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 K
34、bitk interfaces according to ITU-T Recommendation G.703 p, 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. STD-ETSI PRETS 300 Lib!-b-ENGL 1777 3400855 0158112 L7T Page 11 Draft prETS 300 462-6: January 1997 History January 1997 Public Enquiry PE 9722: 1997-01 -31 to 1997-05-30
