SIST EN 300 462-4-1 V1.1.1:2003

• Abstract:

  Stadardises SDH timing distribution architectures, synchronisation network level jitter and wander requirements, slave clock timing specifications and primary reference clock specifications.

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.040.20 - Transmission systems
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI EN 300 462-4-1 V0.0.0 (1998-05) - 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 Plesiochronous Digital Hierarchy (PDH) equipment

SIST EN 300 462-4-1 V1.1.1:2003 is the Slovenian adoption of ETSI EN 300 462-4-1 V1.1.1 for synchronization networks. It specifies the timing characteristics of Synchronization Supply Units (SSUs) used to provide synchronization to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment. The document covers frequency accuracy, pull-in range, noise generation, noise tolerance, transfer behavior, transient response, holdover performance, and the interfaces where these requirements apply.

What does SIST EN 300 462-4-1 V1.1.1:2003 specify?

SIST EN 300 462-4-1 V1.1.1:2003 sets minimum timing performance for SSUs in SDH and PDH synchronization supply applications. It is written for new synchronization network design and for SSUs implemented as stand-alone equipment or as a logical function inside other network equipment.

The document also ties its requirements to environmental classes from ETS 300 019 and to external synchronization interfaces rather than internal clock points.

Annex	What it covers
Annex A	Information on the SSU noise model
Annex B	Measurement method for combined noise transfer and noise generation

The main body is organized into:

• Clause 4 - Frequency accuracy
• Clause 5 - Pull-in and pull-out ranges
• Clause 6 - Noise generation
• Clause 7 - Noise tolerance
• Clause 8 - Transfer characteristic
• Clause 9 - Transient response and holdover performance
• Clause 10 - Interfaces

What are the key requirements of SIST EN 300 462-4-1 V1.1.1:2003?

Frequency and acquisition

Clause 4 says long-term frequency accuracy applies in free-running conditions, but an SSU is normally used locked or in holdover. In practice, that means the holdover behavior is the relevant operating condition, not a simple free-run figure.

Clause 5 sets a minimum pull-in range of ±0,01 ppm. For engineers, this is the range the clock must be able to acquire from when it locks to a reference.

Noise generation, wander, and jitter

Clause 6 limits wander in locked mode using MTIE and TDEV over observation intervals from 0,1 s to 10 000 s, with specified measurement filtering and sampling conditions. This matters because these are the standard metrics used to verify that the SSU does not add excessive timing instability.

Clause 6 also limits output jitter. For 2 048 kHz and 2 048 kbit/s outputs, the intrinsic jitter limit is given for a 60 s measurement, and STM-N outputs have separate limits by interface type and filter band. These limits tell a test lab what to measure at each port type.

Input tolerance and network stress

Clause 7 defines how much input jitter and wander the SSU must tolerate without improper operation, alarms, reference switching, or entry into holdover. It uses masks expressed with MTIE, TDEV, and sinusoidal wander, so a vendor can check whether a clock will stay stable when the incoming timing reference is noisy.

Transfer and holdover behavior

Clause 8 limits the SSU transfer characteristic, including a maximum bandwidth of 3 mHz and a pass-band phase gain below 0,2 dB. It also defines an output wander mask when the input noise follows the specified tolerance shape.

Clause 9 covers reference switching, holdover, and internal disturbances. It sets bounds on phase error during reference changes, gives a holdover phase-error formula with temperature and ageing terms, and adds phase-discontinuity limits for 2 Mbit/s, 2 MHz, and STM-N outputs.

Interfaces

Clause 10 applies the requirements at external synchronization interfaces: 2 048 kHz, 2 048 kbit/s, and STM-N. For users, this means the compliance check is done at the ports that carry synchronization, not at internal clock nodes.

What terms does SIST EN 300 462-4-1 V1.1.1:2003 define?

• Synchronization Supply Unit (SSU) - The timing device whose output supports synchronization of network equipment.
• Maximum Time Interval Error (MTIE) - A timing-wander metric used to describe the worst phase error over an observation interval.
• Time Deviation (TDEV) - A timing-wander metric used to characterize phase variation over time.
• Stand Alone Synchronization Equipment (SASE) - Separate equipment that implements the SSU function.
• Synchronous Transport Module-N (STM-N) - The SDH interface family used for some output-jitter requirements.
• Phase Locked Loop (PLL) - The clock structure used in the SSU noise model described in Annex A.
• Voltage Controlled Oscillator (VCO) - The oscillator element in the SSU model whose behavior affects output timing.

Who uses SIST EN 300 462-4-1 V1.1.1:2003?

This standard is used by telecommunications equipment manufacturers, synchronization-network designers, and test laboratories. It is also useful for quality managers and buyers who need to check whether an SSU, embedded clock, or synchronization interface matches SDH and PDH timing requirements.

Network operators and integrators use it when planning or verifying synchronization supply in SDH transport networks and PSTN environments. Test teams use it to measure MTIE, TDEV, jitter, wander tolerance, and holdover behavior at the specified interfaces.

What changed in SIST EN 300 462-4-1 V1.1.1:2003 from the previous edition?

The foreword states that this version was republished as an EN and that the renumbering of the synchronization-network family created part 4-1 and related parts. It also says that this publication introduced no technical change to the document.

Which standards are used with SIST EN 300 462-4-1 V1.1.1:2003?

• ETS 300 019 - Provides the environmental classes used when applying the SSU requirements.
• EN 300 462-1-1 - Supplies definitions, abbreviations, symbols, and the synchronized clock configuration referenced by the timing masks.
• EN 300 462-2-1 - Describes the synchronization network architecture and the SSU logical function.
• EN 300 462-3-1 - Gives guidance on controlling jitter and wander and on related measurement methods.
• EN 300 462-5-1 - Provides the companion SDH slave-clock part and additional measurement guidance referenced for noise transfer.
• EN 300 462-6-1 - Covers primary reference clock timing characteristics in the same synchronization-network family.
• ETS 300 166 - Defines the physical and electrical characteristics of 2 048 kbit/s-based digital interfaces.
• ITU-T Recommendation G.825 - Gives jitter and wander control requirements for SDH-based digital networks.
• ITU-T Recommendation G.823 - Gives jitter and wander control requirements for 2 048 kbit/s-based digital networks.

What does the SIST EN 300 462-4-1 V1.1.1:2003 document contain?

The document contains requirement tables and figures for MTIE, TDEV, jitter, wander tolerance, and output masks. Clause 6 and clause 7 use tables and plots to show the allowed timing behavior over observation intervals and frequency bands.

Clause 9 contains formulas and figures for reference switching and holdover phase error, including the time-dependent holdover equation. Annex A develops an SSU noise model based on PLL behavior and uses it to justify the timing masks. Annex B gives a measurement setup for TDEV-based noise-transfer testing and a functional model for a TDEV noise generator.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.OMDQMHTransmission 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 Plesiochronous Digital Hierarchy (PDH) equipment33.040.20Prenosni sistemTransmission systemsICS:Ta slovenski standard je istoveten z:EN 300 462-4-1 Version 1.1.1SIST EN 300 462-4-1 V1.1.1:2003en01-december-2003SIST EN 300 462-4-1 V1.1.1:2003SLOVENSKI
STANDARD
EN 300 462-4-1 V1.1.1 (1998-05)European Standard (Telecommunications series)Transmission and Multiplexing (TM);Generic requirements for synchronization networks;Part 4-1: Timing characteristics of slave clockssuitable for synchronization supply toSynchronous Digital Hierarchy (SDH)and Plesiochronous Digital Hierarchy (PDH) equipmentSIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)2ReferenceDEN/TM-03017-4-1 (4a109ico.PDF)KeywordsSynchronization, transmission, SDH, PDHETSIPostal addressF-06921 Sophia Antipolis Cedex - FRANCEOffice address650 Route des Lucioles - Sophia AntipolisValbonne - FRANCETel.: [phone]
Fax: [phone]Siret N° 348 623 562 00017 - NAF 742 CAssociation à but non lucratif enregistrée à laSous-Préfecture de Grasse (06) N° 7803/[e-mail]://www.etsi.frhttp://www.etsi.orgCopyright NotificationNo part may be reproduced except as authorized by written permission.The copyright and the foregoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1998.All rights reserved.SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)3ContentsIntellectual Property Rights.4Foreword.41Scope.62References.63Definitions, abbreviations and symbols.73.1Definitions.73.2Abbreviations.73.3Symbols.74Frequency accuracy.75Pull-in and pull-out ranges.86Noise generation.86.1Wander in locked mode.86.2Non-locked wander.106.3Jitter.106.3.1Output jitter at a 2 048 kHz and 2 048 kbit/s interface.106.3.2Output jitter at a Synchronous Transport Module N (STM-N) interface.107Noise tolerance.107.1Jitter tolerance.117.2Wander tolerance.118Transfer characteristic.149Transient response and holdover performance.159.1Phase response during input reference switching.159.2Phase response during hold-over operation.159.3Phase response to input signal interruptions.169.4Phase discontinuity.1710Interfaces.17Annex A (informative):Information on the SSU noise model.18Annex B (informative):Measurement method for combined noise transfer and noisegeneration.21B.1Functional model of TDEV noise generator.22Bibliography.23History.24SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)4Intellectual Property RightsIPRs essential or potentially essential to the present document may have been declared to ETSI. The informationpertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be foundin ETR 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect ofETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the ETSIWeb server (http://www.etsi.fr/ipr or http://www.etsi.org/ipr).Pursuant to the ETSI Interim IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. Noguarantee can be given as to the existence of other IPRs not referenced in ETR 314 (or the updates on the ETSI Webserver) which are, or may be, or may become, essential to the present document.ForewordThis 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 synchronization networks that are compatible withthe performance requirements of digital networks. It is one of a family of documents covering various aspects ofsynchronization networks:Part 1-1:"Definitions and terminology for synchronization networks";Part 2-1:"Synchronization network architecture";Part 3-1:"The control of jitter and wander within synchronization networks";Part 4-1:"Timing characteristics of slave clocks suitable for synchronization supply to SynchronousDigital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment";Part 4-2:"Timing characteristics of slave clocks suitable for synchronization supply to Synchronous DigitalHierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment ImplementationConformance (ICS) Statement";Part 5-1:"Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy(SDH) equipment";Part 6-1:"Timing characteristics of primary reference clocks";Part 6-2:"Timing characteristics of primary reference clocks Implementation Conformance (ICS)Statement";Part 7-1:"Timing characteristics of slave clocks suitable for synchronization supply to equipment in localnode applications".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 Parts4 and 6, respectively.It was decided to prepare ICS proformas for several of the parts and this necessitated a re-numbering of the individualdocument 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, theopportunity was taken to convert the document type to EN.This has involved no technical change to any of the documents. However part 5-1 has been modified, due to editorialerrors which appeared in ETS 300 462-5.SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)5National transposition datesDate of adoption of this EN:22 May 1998Date of latest announcement of this EN (doa):31 August 1998Date of latest publication of new National Standardor endorsement of this EN (dop/e):28 February 1998Date of withdrawal of any conflicting National Standard (dow):28 February 1998SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)61ScopeThis European Standard (Telecommunications series) outlines requirements for timing devices called SynchronizationSupply Units (SSUs) used in synchronizing network equipment in the Synchronous Digital Hierarchy (SDH) transportnetwork and the Public Switched Telephone Network (PSTN) network.NOTE 1:The requirements in the present document apply under environmental conditions according to one of theenvironmental classes defined in ETS 300 019 [1], unless stated otherwise. The manufacturer will need tospecify to which specific environmental class an equipment belongs.A description of the Synchronization Supply Unit (SSU) logical function is given in figure 1 in EN 300 462-2-1 [3]. Ingeneral, the SSU will have multiple timing reference inputs and in the event that all timing references fail, the SSUshould be capable of maintaining operation (holdover) within prescribed performance limits as detailed in the presentdocument. The requirements laid down in the present document decribe the minimum performance of an SSU applied asa transit node clock. It is recognized that local node clock applications for SSU’s exist, requiring different parameters.Those are for further study.NOTE 2:There can be situations in which more stringent requirements are applicable, for instance, in cases wherean 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-Alone SynchronizationEquipment (SASE) or it can form a logical function of another equipment such as a telephony exchange or an SDHcross-connect.The requirements specified in the present document refer to the design of new synchronization networks andconsequently they do not necessarily represent the performance of existing synchronization networks and equipment.A timing device within SDH equipment can also conform to EN 300 462-5-1 [5].2ReferencesThe following documents contain provisions which, through reference in this text, constitute provisions of the presentdocument.· References are either specific (identified by date of publication, edition number, version number, etc.) ornon-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 later versions published as an EN with the samenumber.[1]ETS 300 019: "Equipment Engineering (EE); Environmental conditions and environmental testsfor telecommunications equipment".[2]EN 300 462-1-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 1-1: Definitions and terminology for synchronization networks".[3]EN 300 462-2-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 2-1: Synchronization network architecture".[4]EN 300 462-3-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 3-1: The control of jitter and wander within synchronization networks".[5]EN 300 462-5-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 5-1: Timing characteristics of slave clocks suitable for operation in SynchronousDigital Hierarchy (SDH) equipment".SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)7[6]EN 300 462-6-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 6-1: Timing characteristics of primary reference clocks".[7]ETS 300 166: "Transmission and Multiplexing (TM); Physical and electrical characteristics ofhierarchical digital interfaces for equipment using the 2 048 kbit/s-based pleisiochronous orsynchronous digital hierarchies".[8]ITU-T Recommendation G.825: "The control of jitter and wander within digital networks whichare based on the synchronous digital hierarchy (SDH)".[9]ITU-T Recommendation G.823: "The control of jitter and wander within digital networks whichare based on the 2 048 kbit/s hierarchy".3Definitions, abbreviations and symbols3.1DefinitionsFor the purposes of the present document, the definitions given in EN 300 462-1-1 [2] apply.3.2AbbreviationsFor the purposes of the present document, the abbreviations given in EN 300 462-1-1 [2], together with the following,apply:MTIEMaximum Time Interval ErrorNENetwork ElementPDHPlesiochronous Digital HierarchyPLLPhase Locked Loopppmparts per millionPSTNPublic Switched Telephone NetworkSASEStand Alone Synchronization EquipmentSDHSynchronous Digital HierarchySECSDH Equipment ClockSSUSynchronization Supply UnitSTM-NSynchronous Transport Module-NTDEVTime DEViationUIUnit IntervalUIppUnit Interval peak to peakVCOVoltage Controlled Oscillator3.3SymbolsFor the purposes of the present document, the following symbols apply:KKelvintTau4Frequency accuracyThe long term frequency accuracy normally applies when operating in long term free running conditions. Since the SSUis a slave clock, then the normal operating modes are either locked or holdover. The frequency accuracy specification inholdover mode is specified in clause 9.SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)85Pull-in and pull-out rangesThe minimum pull-in range shall be ± 0,01 ppm, whatever the internal oscillator frequency offset may be. The pull-outrange is for further study.6Noise generationThe noise generation of an SSU represents the amount of phase noise produced at the output when there is an ideal inputreference signal or the clock is in holdover state. A suitable reference, for practical testing purposes, implies aperformance level at least 10 times more stable than the output requirements. The ability of the clock to limit this noiseis described by its frequency stability. The measures Maximum Time Interval Error (MTIE) and Time Deviation(TDEV) are useful for characterization of noise generation performance.For observation intervals, t, between 0,1 s and 10 000 s, MTIE and TDEV are measured through an equivalent 10 Hz,first order, low-pass measurement filter, at a maximum sampling time t0 of 1/30 second. The minimum measurementperiod, T, for TDEV is twelve times the observation interval (T = 12t). Further guidance is provided in clause A.2 ofEN 300 462-3-1 [4].6.1Wander in locked modeWhen the SSU is in the locked mode of operation, the MTIE and TDEV measured using the synchronized clockconfiguration defined in figure 1a) of EN 300 462-1-1 [2] shall have the limits in tables 1 and 2, if the temperature isconstant (± 1 K).Table 1: Wander in locked mode for constant temperature specified in TDEVRequirementObservation interval3 ns0,1 < t £ 25 s0,12t ns25 < t £ 100 s12 ns100 < t £ 10 000 sTable 2: Wander in locked mode for constant temperature specified in MTIERequirementObservation interval24 ns0,1 < t £ 9 s8t0,5 ns9 < t £ 400 s160 ns400 < t £ 10 000 sThe model used to derive these numbers is described in (informative) annex A. The resultant requirements areshown by the thick solid lines in figures 1 and 2.SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)91001,0TDEV1025100(ns)(constant temperature)TDEV(log scale)1230,11,01 kObservation Interval
(s)(log scale)t1010 kFigure 1: TDEV as a function of an observation interval tt1011 0001000,1160241,0101001 k(ns)(constant temperature)MTIE9400Observation Interval(Log scale)(s)t(Log scale)10 k(variable temperature)3202,5 kFigure 2: MTIE as a function of an observation interval ttWhen temperature effects are included of which the limits and rate of change are defined in ETS 300 019 [1],corresponding to the environmental class to which the equipment belongs, the allowance for the total MTIE contributionof a single SSU is given by the values in table 3.Table 3: Total wander in locked mode for variable temperature specified in MTIERequirementObservation interval3,2 ´ t0,52 500 to 10 000 sNOTE:For observation intervals greater than 10 000 s the MTIE is expected not to exceed 320 ns.The resultant requirement is shown by the upper solid line in figure 2.SIST EN 300 462-4-1 V1.1.1:2003

ETSIEN 300 462-4-1 V1.1.1 (1998-05)106.2Non-locked wanderWhen a clock is not locked to a synchronization reference, the random noise components are negligible compared todeterministic effects like initial frequency offset. Consequently the non-locked wander effects are included insubclause 9.2.6.3JitterWhile most specifications in the present document are independent of the output interface at which they are measured,this is not the case for jitter production; jitter generation specifications shall utilize existing specifications that arecurrently specified differently for different interface rates. These requirements are stated separately for the interfacesidentified in clause 10. To be consistent with other jitter requirements the specifications are in Unit Interval peak to peak(UIpp), where the Unit Interval (UI) corresponds to the reciprocal of the bit rate of the interface.Due to the stochastic nature of jitter, the peak-to-peak values given in this clause eventually are exceeded. Therequirements shall therefore be fulfilled with a probability of 99 %.6.3.1Output jitter at a 2 048 kHz and 2 048 kbit/s interfaceIn the absence of input jitter, the intrinsic jitter at a 2 048 kHz or 2 048 kbit/s output interface as measured over a60 seconds interval shall not exceed 0,05 UIpp when measured through a band-pass filter with corner frequencies at20 Hz and 100 kHz each with a first order 20 dB/decade roll-off characteristic.6.3.2Output jitter at a Synchronous Transport Module N (STM-N)interfaceIn the absence of input jitter at the synchronization interface, the intrinsic jitter at STM-N output interfaces as measuredover a 60 seconds interval shall not exceed the limits given in table 4.Table 4: Output jitter requirements for STM-N interfacesInterfaceMeasuring filter(Hz)Peak-to-peak amplitude(UI)STM-1 electrical500 to 1,3 M0,5065 k to 1,3 M0,075STM-1 optical500 to 1,3 M0,5065 k to 1,3 M0,10STM-41 k to 5 M0,50250 k to 5 M0,10STM-165 k to 20 M0,501 M to 20 M0,10NOTE:for STM-1:1 UI = 6,43 ns;for STM-4:1 UI = 1,61 ns;for STM-16:1 UI = 0,40 ns.7Noise toleranceNoise tolerance of an SSU indicates the minimum phase noise level at the input of the clock that should beaccommodated whilst:-maintaining the clock within prescribed performance limits in locked mode of operat
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