1、EN 300 462-4-1 1.1.1 (1998-05) European Standard (Te/ecommunications series) Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 4-1 : Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesioc
2、hronous Digital Hierarchy (PDH) equipment 2 EN 300 462-4-1 V1.l.l (1998-05) Reference DENTTM-03017-4-1 (4al 09ico.PDF) Keywords Synchronization, transmission, SDH, PDH ETSI Postai address F-O6921 Sophia Antipolis Cedex - FRANCE Office address 650 Route des Lucioles - Sophia Antipolis Valbonne - FRAN
3、CE Tel.: +33 4 92 94 42 O0 Fax: +33 4 93 65 47 16 Sirat No 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) No 7803/88 Internet secretariat etsi.fr http:/www.etsi .f r http:/www.etci.org Copyright Notification No part may be reproduced except as
4、authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media O European Telecommunications Standards Institute 1998. All rights reserved. ETSI 3 EN 300 462-4-1 V1.l.l (1998-05) Contents intellectual Property Rights 4 Foreword 4 1 2 3 3.1 3.2 3.3 4
5、 5 6 6.1 6.2 6.3 Scope 6 References 6 Definitions, abbreviations and symbols . 7 . . 7 Definitions 7 7 Frequency accuracy 7 Puii-in and puii-out ranges . 8 Noise generation 8 Wander in locked mode Non-locked wander . Jitter . . 6.3.1 6.3.2 7 Noise tolerance . 10 7.1 Jitter tolerance . 11 7.2 Wander
6、tolerance . . 11 8 Transfer characteristic 14 9 Transient response and holdover performance 15 9.1 9.2 Phase response dun 15 9.3 Phase response to i . 9.4 Phase discontinuity 17 10 Interfaces 17 Output jitter at a 2 048 kHz and 2 O48 kbit/s interface . Output jitter at a Synchronous Transport Module
7、 N (STM-N) interface . 10 . Phase response during input reference switching Annex A (informative): Annex B (informative): B.l Functional model of TDEV noise generator 22 Bibliography . 23 History 24 Information on the SSU noise model . 18 Measurement method for combined noise transfer and noise gene
8、ration . 21 ETSI STDDETSI EN 300 462-4-L-ENGL 1998 3400855 0337757 043 D 4 EN 300 462-4-1 V1.l.l (1 998-05) Intellectual Property Rights PRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publi
9、cly available for ETSI members and non-members , and can be found in ETR 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notifed to ETSI in respect of ETSI standards“, which is available free of charge from the ETSI Secretariat. Latest updates are available on th
10、e ETSI Web server (http:/www.etsi.fr/ipr or http:/www.etsi.org/ipr). Pursuant to the ETSI Interim PR Policy, no investigation, including IPR searches, has been carried out by ETSI. NO guarantee can be given as to the existence of other IPRs not referenced in ETR 314 (or the updates on the ETSI Web s
11、erver) which are, or may be, or may become, essential to the present document. Foreword This European Standard (Telecommunications series) has been produced by the Transmission and Multiplexing (TM) Technical Committee. The present document has been produced to provide requirements for synchronizati
12、on networks that are compatible with the performance requirements of digital networks. It is one of a family of documents covering various aspects of synchronization networks: Part 1-1: Part 2-1: “Synchronization network architecture“; Part 3-11 Part 4-1: “Definitions and terminology for synchroniza
13、tion networks“; “The control of jitter and wander within synchronization networks“; “Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment“; “Timing characteristics of slave clocks suitab
14、le for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment Implementation Conformance (ICs) Statement“; “Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy (SDH) equipment“; “Timing characteris
15、tics of primary reference clocks“; “Timing characteristics of primary reference clocks Implementation Conformance (ICs) Statement “; Part 4-2: Pat 5-1: Part 6-1: Part 6-2: Part 7-1: “Timing characteristics of slave clocks suitable for synchronization supply to equipment in local node applications“.
16、Parts 1-1, 2-1, 3-1 and 5-1 have previously been published as ETS 300 462 Parts 1,2, 3 and 5, respectively. Additionally, parts 4-1 and 6-1 completed the Voting phase of the Two Step Approval procedure as ETS 300 462 Parts 4 and 6, respectively. It was decided to prepare ICs proformas for several of
17、 the parts and this necessitated a re-numbering of the individual document parts. It was also decided to create a new part 7-1. This in turn led to a need to re-publish new versions of all six parts of the original ETS. At the same time, the opportunity was taken to convert the document type to EN.
18、This has involved no technical change to any of the documents. However part 5-1 has been modified, due to editorial errors which appeared in ETS 300 462-5. ETSI - STD-ETSI EN 300 YbZ-q-L-ENGL 1998 m 3400855 0337758 T88 m 5 EN 300 462-4-1 V1.l.l (1998-05) National transposition dates Date of adoption
19、 of this EN: Date of latest announcement of this EN (doa): 22 May 1998 31 August 1998 Date of latest publication of new National Standard or endorsement of this EN (dop/e): 28 February 1998 Date of withdrawal of any conflicting National Standard (dow): 28 February 1998 I 6 EN 300 462-41 V1.l.l (1998
20、-05) 1 Scope This European Standard (Telecommunications series) outlines requirements for timing devices called Synchronization Supply Units (SSUs) used in synchronizing network equipment in the Synchronous Digital Hierarchy (SDH) transport network and the Public Switched Telephone Network (PSTN) ne
21、twork. NOTE 1: The requirements in the present document apply under environmental conditions according to one of the environmental classes defined in ETS 300 019 i, unless stated otherwise. The manufacturer will need to specify to which specific environmental class an equipment belongs. A descriptio
22、n of the Synchronization Supply Unit (SSU) logical function is given in figure 1 in EN 300 462-2-1 3. in general, the SSU will have multiple timing reference inputs and in the event that all timing references fail, the SSU should be capable of maintaining operation (holdover) within prescribed perfo
23、rmance limits as detailed in the present document. The requirements laid down in the present document decribe the minimum Performance of an SSU applied as a transit node clock. It is recognized that local node clock applications for SSUs exist, requiring different parameters. Those are for further s
24、tudy. NOTE 2: There can be situations in which more stringent requirements are applicable, for instance, in cases where an SSU has only one independent reference (e.g. due to limitations in the network topology). The SSU function can be implemented in a separate piece of equipment called a Stand-Alo
25、ne Synchronization Equipment (SASE) or it can form a logical function of another equipment such as a telephony exchange or an SDH cross-connec t. The requirements specified in the present document refer to the design of new synchronization networks and consequently they do not necessarily represent
26、the performance of existing synchronization networks and equipment. A timing device within SDH equipment can also conform to EN 300 462-5-1 5. 2 Ref ere nces The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References ar
27、e either specific (identified by date of publication, edition number, version number, etc.) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific reference, subsequent revisions do apply. A non-specific reference to an ETS shall also be taken to refer to la
28、ter versions published as an EN with the same number. 111 ETS 300 O 19: “Equipment Engineering (EE); Environmental conditions and environmental tests for telecommunications equipment“. EN 300 462-1-1 : “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 1-1 :
29、 Definitions and terminology for synchronization networks“. EN 300 462-2-1 : “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 2-1: Synchronization network architecture“. EN 300 462-3-1: “Transmission and Multiplexing (TM); Generic requirements for synchron
30、ization networks; Part 3-1: The control of jitter and wander within synchronization networks“. EN 300 462-5-1 : “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 5-1: Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hiera
31、rchy (SDH) equipment“. Pl t31 41 i51 ETSf - STD-ETSI EN 300 462-4-1-ENGL 1998 3400855 03177b0 b3b W 7 EN 300 462-41 Vl.l.1 (1998-05) 61 EN 300 462-6-1 : “Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 6-1: Timing characteristics of primary reference clock
32、s“. ETS 300 166: “Transmission and Multiplexing (TM); Physical and electrical characteristics of hierarchical digital interfaces for equipment using the 2 048 kbit/s-based pleisiochronous or synchronous digital hierarchies“. IT-T Recommendation G.825: “The control of jitter and wander within digital
33、 networks which are based on the synchronous digital hierarchy (SDH)“. IT-T Recommendation G.823: “The control of jitter and wander within digital networks which are based on the 2 O48 kbith hierarchy“. t7 1 BI i91 3 3.1 Definitions, abbreviations and symbols Def i n it ions For the purposes of the
34、present document, the definitions given in EN 300 462-1-1 23 apply. 3.2 Abbreviations For the purposes of the present document, the abbreviations given in EN 300 462-1-1 2, together with the following, apply: MTIE NE PDH PLL PPm PSTN SASE SDH SEC ssu STM-N TDEV u1 VCO UIPP 3.3 Maximum Time Interval
35、Error Network Element Plesiochronous Digital Hierarchy Phase Locked Loop parts per million Public Switched Telephone Network Stand Alone Synchronization Equipment Synchronous Digital Hierarchy SDH Equipment Clock Synchronization Supply Unit Synchronous Transport Module-N Time DEViation Unit Interval
36、 Unit Interval peak to peak Voltage Controlled Oscillator Symbols For the purposes of the present document, the following symbols apply: K Kelvin T Tau 4 Frequency accuracy The long term frequency accuracy normally applies when operating in long term free running conditions. Since the SSU is a slave
37、 clock, then the normal operating modes are either locked or holdover. The frequency accuracy specification in holdover mode is specified in clause 9. ETSI STD-ETSI EN 300 462-4-1-ENGL 1998 3400855 0317761 572 EN 300 462-4-1 V1.l.l (1998-05) 8 Requirement 3 ns O, 122 ns 12 ns 5 Observation interval
38、0,l c.tI25s 25 B. From a practical point of view it is very useful to relate model parameters B, Kf, and Kw to characteristic features of TDEV curves: assuming TO = O,ls, Bn = 5 Hz , and 6, = 1 ns in the above equations the following simple formulas are derived: TDEV(T) = K, nsl for B Il Hz TDEV(w)
39、= 1,075 Kf ns Tc = 0,3 1+, s d B1 ETSI 20 EN 300 462-4-1 V1.l.l (1 998-05) The resulting asymptotic TDEV behaviour is shown in figure A.2. TDEV( m) TDEV( 0) TO TC Figure A.2: Asymptotic TDEV behaviour of the SSU model Observation interval z Assuming the TDEV mask in figure 1 of the main body, model
40、parameters can be calculated to completely define a clock model compliant with the mask itself: from the 12 ns TDEV plateau and from the breakpoint at 100 s, Kf = 11 O00 and 6 = 3 mHz can be estimated, whereas, considering white phase noise dominating at lower observation intervals, the TDEV 3 ns le
41、vel is consistent with K, = 3 (the 5r+ O expression applies). Given these values for the Kf, K, and B parameters and the approximate expressions above, the asymptotic TDEV and MTIE curves in figure A.3 result: modelled TDEV confirms compliance with the proposed TDEV mask (also reported in figure A.3
42、), while modelled MTIE is used as a basis to consistently define the proposed MTiE mask, shown in figure A.3 as well. 1 O00 1 O0 c 10 1 0.1 Figure A.3: Consistency between proposed masks and modelled asymptotic expressions - - - STDmETSI EN 300 462-4-1-ENGL 3998 3900855 0337774 320 21 EN 300 462-4-1
43、 V1.l.l (1 998-05) Annex B (informative): Measurement method for combined noise transfer and no generation Methods suitable for testing the requirements of clause 8 (a) are described in annex B in EN 300 462-5-1 5. The measurement method recommended here directly tests conformance with the noise tra
44、nsfer specification of clause by applying the TDEV input noise tolerance limit, figure 4, as the test signal. The output TDEV characteristic is then directly compared against the specification limit, figure 7. The measurement set-up is shown in figure B. 1. (Cal i brat ion) -y I I SSU 6 SSUoutput un
45、der c- test Synchronization measure Figure 8.1 : Measurement Set-up for TDEV noise transfer characteristics To ensure sufficiently accurate, robust and consistent measurements, the following principles should be applied: 1) The test signal should be deterministic, yet sufficiently noise-like over a
46、short observation interval. 2) The noise generator should produce a test signal within f 20 ?h of the input noise tolerance specification - subclause 7.2, figure 4. 3) At large values of z, the TDEV results should match the TDEV output mask within * 2 70 of the specification - clause 8, figure 7. In
47、 order to achieve the above levels of accuracy, normalization and calibration techniques should be applied. In general, the following procedure is recommended: 1) Perform a calibration measurement sequence, without the SSU under test - TDEV(ca1ibration). This obtains the raw test signal characterist
48、ics. 2) Calculate a correction factor with respect to the required input wander tolerance specification - TDEV(reference). This now represents the ideal test signal. 3) Measure TDEV(dat) of the SSU under test under the same conditions as the calibration sequence. 4) Normalize TDEV(dat) using TDEV(re
49、ference) - obtaining TDEV(measured). 5) TDEV(measured) may now be directly compared with the noise transfer specification limit. STD-ETSI EN 300 462-4-1-ENGL 1998 3400855 0317775 Ob7 PRBS Generator - Period 150 hrs 22 EN 300 462-4-1 V1.l.l (1998-05) Clock Phase Modulation TDEV -x Invert every - Low-pass weighting filter 7 Other bit Filter B.1 Functional model of TDEV noise generator Figure B.2: Functional model of TDEV noise generator ETSI STD=ETSI EN 300 462-4-1-ENGL 1998 3400855 0317776 TT3 23 EN 300 462-4-1 Vi
