SIST EN 300 420 V1.2.1:2004

• Abstract:

  Revision to improve the safety related text following a liaison from TC Safety. Specification of the terminal equipment side of the interface and test procedures for compliance.

• Status: Published
• Publication Date: 30-Sep-2004
• ICS: 33.040.50 - Lines, connections and circuits
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Oct-2004
• Due Date: 01-Oct-2004
• Completion Date: 01-Oct-2004
• Mandate: T-147-2
• Ref Project: ETSI EN 300 420 V1.2.1 (2001-07) - Access and Terminals (AT); 2 048 kbit/s digital structured leased lines (D2048S); Terminal equipment interface

SIST EN 300 420 V1.2.1:2004 is the SIST version of ETSI EN 300 420 Version 1.2.1. It specifies the terminal equipment interface for Access and Terminals (AT) 2 048 kbit/s digital structured leased lines (D2048S), including the physical and electrical interface, the functional behaviour, and the test principles used to check conformity. In practice, it is the document for equipment that must connect to Open Network Provision (ONP) 2 048 kbit/s structured leased lines over a 120 Ω interface.

What does SIST EN 300 420 V1.2.1:2004 specify?

SIST EN 300 420 V1.2.1:2004 specifies the terminal equipment side of the D2048S interface and the tests used to verify it. It covers compatibility with ONP 2 048 kbit/s digital structured leased lines, and notes that compliant terminal equipment is also compatible with ONP 2 048 kbit/s unstructured leased lines.

The document is organized around one main requirements clause, a normative test annex, a normative code definition annex, a normative frame definition annex, a normative requirements table, and informative annexes on timing and bibliography.

Annex	What it covers
A	Test methods for compliance
B	Definition of HDB3 code
C	Definition of frame structure and CRC-4
D	Requirements Table (RT)
E	Timing synchronization guidance
F	Bibliography

What are the key requirements of SIST EN 300 420 V1.2.1:2004?

SIST EN 300 420 V1.2.1:2004 focuses on how the terminal equipment must connect, signal, time, and frame data so that it can operate on the leased line without errors. The most important points are below.

Physical connection and wiring

Clause 4.1.1 requires the equipment to accept solid wire conductors in the 0.4 mm to 0.6 mm range, either through connection contacts or a wired arrangement. This matters because installers need a practical field connection method, not just a theoretical interface.

Output signal and timing

Clause 4.2.1.1 requires HDB3 coding, and clause 4.2.1.2 defines the pulse shape against a mask based on ITU-T Recommendation G.703. Clause 4.2.1.3 requires an internal clock within 2048 kbit/s ±50 ppm and the ability to loop timing from the input port. In practice, this ensures the terminal can work with both user timing and network timing arrangements.

Output jitter and grounding

Clause 4.2.1.5 limits output jitter, and clauses 4.2.1.4 and 4.2.2.6 require the input and output impedances towards ground to be greater than 1000 Ω in the stated frequency range when a ground exists. This is important for interoperability and for implementations that avoid transformers.

Input signal behaviour

Clause 4.2.2.1 requires correct decoding of HDB3 signals. Clause 4.2.2.2 sets minimum return loss, clause 4.2.2.3 sets input loss tolerance, clause 4.2.2.4 checks immunity against reflections, and clause 4.2.2.5 checks tolerance to longitudinal voltage. Together, these requirements define how well the receiver survives real cabling and interference.

Jitter and clock tolerance

Clause 4.2.2.7 defines input jitter tolerance, and clause 4.2.2.8 requires error-free decoding over 2048 kbit/s ±50 ppm. Clause A.2.8 shows how the tests are run for both input tolerance and output jitter. For users, this means the interface must keep working when the line timing is not ideal.

Frame structure, CRC-4, E-bit, A-bit, and frame alignment

Clause 4.2.1.8 requires the output bitstream to follow the defined frame structure in Annex C. Clause 4.2.1.8.1 covers CRC-4 generation, clause 4.2.1.8.2 covers E-bit use, clause 4.2.1.8.3 covers A-bit behaviour, and clause 4.2.2.9 covers frame and multiframe alignment at the input. In practice, these rules let the terminal separate user data from overhead and react correctly to errored sub-multiframes.

What terms does SIST EN 300 420 V1.2.1:2004 define?

• Network Termination Point (NTP) - The physical network connection and its access specification that form part of the public network.
• Sub-MultiFrame (SMF) - A block of 8 frames over which CRC-4 is calculated.
• CRC-4 - A cyclic redundancy check using 4 bits to detect errored SMFs.
• HDB3 - High Density Bipolar code of order 3, the line code used on the interface.
• PRBS (2^15-1) - A pseudo-random bit sequence used in testing.
• AIS - Alarm Indication Signal, used in the tests as a stimulus that causes loss of frame alignment.
• RAI - Remote Alarm Indication, one of the frame bits used in the defined structure.

Who uses SIST EN 300 420 V1.2.1:2004?

SIST EN 300 420 V1.2.1:2004 is used by terminal equipment designers, telecom engineers, and compliance laboratories working on 2 048 kbit/s leased-line interfaces. It is also relevant to network operators and buyers who need to specify or verify interface compatibility for ONP leased lines. Quality and test teams use it to plan conformance tests, especially for coding, framing, jitter, and timing behaviour.

What changed in SIST EN 300 420 V1.2.1:2004 from the previous edition?

This version revises the safety-related text following a liaison from TC Safety. The foreword also shows that it is based on an earlier ETS and that it belongs to the ETSI AT series for leased-line interfaces.

Which standards are used with SIST EN 300 420 V1.2.1:2004?

• ITU-T Recommendation G.703 - Provides the physical and electrical interface basis used for signal shape and related characteristics.
• ITU-T Recommendation G.704 - Provides the synchronous frame structure used for the 2 048 kbit/s hierarchy.
• ITU-T Recommendation O.151 - Provides the PRBS definition used in testing.
• ITU-T Recommendation O.171 - Provides jitter and wander measuring equipment guidance used in jitter tests.
• ETSI EN 300 418 - Covers the network interface presentation for 2 048 kbit/s digital unstructured and structured leased lines.
• ETSI EN 300 419 - Covers the connection characteristics for D2048S.

What does the SIST EN 300 420 V1.2.1:2004 document contain?

The document contains the requirements table, test methods, and the detailed definitions needed to verify the interface. Annex A gives the test configurations and procedures for coding, waveform shape, timing, return loss, reflections, longitudinal voltage, jitter, and frame structure. Annex C provides the frame layout, CRC-4 generation, and CRC-4 monitoring rules, while Annex D summarizes which requirements are mandatory, optional, or not requirements. For design and certification work, the useful material is the combination of tables, masks, bit allocations, and test setups rather than just the short clause statements.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Dostop in terminali (AT) - Digitalni zakupljeni vodi za prenosno hitrost 2 048 kbit/s in za strukturirane signale (D2048S) - Vmesnik terminalske opremeAccess and Terminals (AT); 2 048 kbit/s digital structured leased lines (D2048S); Terminal equipment interface33.040.50Vodi, zveze in tokokrogiLines, connections and circuitsICS:Ta slovenski standard je istoveten z:EN 300 420 Version 1.2.1SIST EN 300 420 V1.2.1:2004en01-oktober-2004SIST EN 300 420 V1.2.1:2004SLOVENSKI
STANDARD
ETSIEN300420V1.2.1(2001-07)EuropeanStandard(Telecommunicationsseries)AccessandTerminals(AT);2048kbit/sdigitalstructuredleasedlines(D2048S);TerminalequipmentinterfaceSIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)2ReferenceREN/AT-020007Keywordsdigital,leasedline,network,ONP,terminalETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:[phone]Fax:[phone]SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88ImportantnoticeIndividualcopiesofthepresentdocumentcanbedownloadedfrom:http://www.etsi.orgThepresentdocumentmaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.Usersofthepresentdocumentshouldbeawarethatthedocumentmaybesubjecttorevisionorchangeofstatus.InformationonthecurrentstatusofthisandotherETSIdocumentsisavailableathttp://www.etsi.org/tb/status/Ifyoufinderrorsinthepresentdocument,sendyourcommentto:[e-mail]opartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2001.Allrightsreserved.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)3ContentsIntellectualPropertyRights.5Foreword.5Introduction.61Scope.72References.73Definitionsandabbreviations.83.1Definitions.83.2Abbreviations.84Requirements.94.1Physicalcharacteristics.94.1.1Hardwiredconnection.104.1.2Alternativemeansofconnection.104.2Electricalcharacteristics.104.2.1Outputport.104.2.1.1Signalcoding.104.2.1.2Waveformshape.104.2.1.3Outputtiming.114.2.1.4Impedancetowardsground.124.2.1.5Outputjitter.124.2.1.6Outputreturnloss.124.2.1.7Outputsignalbalance.124.2.1.8Outputstructure.124.2.1.8.1CRC-4.134.2.1.8.2UseoftheE-bits.134.2.1.8.3UseoftheA-bit.134.2.1.8.4UseoftheSabits.144.2.2Inputport.144.2.2.1Signalcoding.144.2.2.2Inputreturnloss.144.2.2.3Inputlosstolerance.144.2.2.4Immunityagainstreflections.154.2.2.5Tolerablelongitudinalvoltages.154.2.2.6Impedancetowardsground.154.2.2.7Inputjittertolerance.154.2.2.8Inputclocktolerance.164.2.2.9Inputframestructure.164.2.2.9.1Framealignment.164.2.2.9.2Multiframealignment.174.3Safety.174.4Overvoltage.174.5ElectroMagneticCompatibility(EMC).17AnnexA(normative):Testmethods.18A.1General.18A.1.1Additionalinformationtosupportthetest.18A.1.2Equipmentconnection.18A.2Testmethods.19A.2.1Signalcodingattheoutputport.19A.2.2Waveformshapeatoutputport.19A.2.3Outputtiming.20A.2.4Returnlossatinputport.21A.2.5Inputlosstoleranceandimmunityagainstreflections.21SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)4A.2.6Tolerablelongitudinalvoltage,HDB3inputcoding.23A.2.7Impedancetowardsground.24A.2.8Inputandoutputjitter.24A.2.9Framestructure.26A.2.9.1OutputstructureandCRC-4generation.26A.2.9.2TerminalsnotusingtheE-bits.27A.2.9.3TerminalsusingtheE-bitstoindicateerroredSMFs.27A.2.9.4UseoftheA-bit.28A.2.10Inputframestructure.29A.2.10.1Framealignment.29A.2.10.2Multiframealignment.30AnnexB(normative):DefinitionofHDB3code.32B.1General.32B.2Definition.32AnnexC(normative):Definitionofframestructure.33C.1Framestructure.33C.2CRC-4.33C.2.1CRC-4generation.34C.2.2CRC-4monitoring.34AnnexD(normative):RequirementsTable(RT).35AnnexE(informative):Timingsynchronization.37E.1General.37E.1.1Usertiming.37E.1.2Networktiming.37E.2Furtherinformation.38AnnexF(informative):Bibliography.39History.40SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)5IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinETSISR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinETSISR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbyETSITechnicalCommitteeAccessandTerminals(AT).ThepresentdocumentresultsfromamandatefromtheCommissionoftheEuropeanCommunity(CEC)toprovidestandardsforthesupportoftheDirectiveonOpenNetworkProvision(ONP)ofleasedlines(92/44/EEC).Therearetwootherstandardsdirectlyrelatedtothepresentdocument:-EN300418:"AccessandTerminals(AT);2048kbit/sdigitalunstructuredandstructuredleasedlines(D2048UandD2048S);Networkinterfacepresentation";-EN300419:"AccessandTerminals(AT);2048kbit/sdigitalstructuredleasedlines(D2048S);Connectioncharacteristics".ThepresentdocumentisbasedoninformationfromITU-TRecommendationsandETSIpublicationsandtherelevantdocumentsarequotedwhereappropriate.NationaltranspositiondatesDateofadoptionofthisEN:29June2001DateoflatestannouncementofthisEN(doa):30September2001DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):31March2002DateofwithdrawalofanyconflictingNationalStandard(dow):31March2002SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)6IntroductionTheCouncilDirectiveontheapplicationofONPtoleasedlines(92/44/EEC)concernstheharmonizationofconditionsforopenandefficientaccessto,anduseof,theleasedlinesprovidedoverpublictelecommunicationsnetworks,andtheavailabilitythroughouttheEuropeanUnion(EU)ofaminimumsetofleasedlineswithharmonizedtechnicalcharacteristics.TheconsequenceoftheDirectiveisthattelecommunicationsorganizationswithintheEUshallmakeavailableasetofleasedlinesbetweenpointsinthesecountrieswithspecifiedconnectioncharacteristicsandspecifiedinterfaces.Twocategories(voluntaryandregulatory)ofstandardwereusedfortheinterfacesofterminalequipmentdesignedforconnectiontotheONPleasedlines.TechnicalBasisforRegulations(TBRs)gavetheearlieressentialrequirementsundertheDirective91/263/EEC,laterreplacedby98/13/EC,forattachmenttotheleasedlines,whereasothervoluntarystandards(ETSsorENs)gavethefulltechnicalspecificationsfortheseinterfaces.Thisdocument,whichisbasedonanearlierETS,belongstothesecondcategory.TherequirementsofTBR13areasubsetofthepresentdocument.Thepresentversionofthepresentdocumenthasbeenproducedtointroducesomenecessarychanges.ETS300166andITU-TRecommendationsG.703[1],G.704[2]andG.706wereusedasthebasisfortheterminalinterfaceaspectsofthepresentdocument.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)71ScopeThepresentdocumentspecifiesthephysicalandelectricalcharacteristics(exceptsafety,overvoltageandEMCaspects),thenecessaryfunctionalcharacteristicsandthecorrespondingtestprinciplesforaterminalequipmentinterfaceforconnectiontotheNetworkTerminationPoints(NTPs)ofOpenNetworkProvision(ONP)2048kbit/sdigitalstructuredleasedlinesusing120Ωinterfaceswithaninformationtransferrateof1984kbit/swithoutrestrictiononbinarycontent.ThepresentdocumentistoensurethattheinterfaceoftheterminalequipmentiscompatiblewiththeONP2048kbit/sdigitalstructuredleasedline.AterminalequipmentinterfacethatconformstothepresentdocumentwillalsobecompatiblewithanONP2048kbit/sunstructuredleasedline.Thepresentdocumentisapplicabletoallinterfacesdesignedforconnectiontotheleasedline,howeverinthecasesofapparatusthatcarriesaparticularservice,ofcomplexapparatusandofapparatusinprivatenetworks,otherrequirementsmayapplyinadditiontothepresentdocument.CustomerpremiseswiringandinstallationbetweentheterminalequipmentandtheNTPareoutsidethescopeofthepresentdocument.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublicationand/oreditionnumberorversionnumber)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,thelatestversionapplies.[1]ITU-TRecommendationG.703(1998):"Physical/electricalcharacteristicsofhierarchicaldigitalinterfaces".[2]ITU-TRecommendationG.704(1998):"Synchronousframestructuresusedat1544,6312,2048,8448and44736kbit/shierarchicallevels".[3]ITU-TRecommendationO.151(1992):"Errorperformancemeasuringequipmentoperatingattheprimaryrateandabove".[4]ITU-TRecommendationO.171(1997):"Timingjitterandwandermeasuringequipmentfordigitalsystemswhicharebasedontheplesiochronousdigitalhierarchy(PDH)".[5]ETSIEN300418:"AccessandTerminals(AT);2048kbit/sdigitalunstructuredandstructuredleasedlines(D2048UandD2048S);Networkinterfacepresentation".[6]ETSIEN300419:"AccessandTerminals(AT);2048kbit/sdigitalstructuredleasedlines(D2048S);Connectioncharacteristics".SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)83Definitionsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply:erroredSub-MultiFrame:Sub-MultiFrame(SMF)wherethecalculatedCyclicRedundancyCheck-4bit(CRC-4)doesnotcorrespondwiththeCRC-4containedwithinthenextSMF(seeclauseC.2.2)frame:sequenceof256bitsofwhichthefirst8bitsdefinetheframestructure(seeannexC)leasedlines:telecommunicationsfacilitiesprovidedbyapublictelecommunicationsnetworkthatprovidedefinedtransmissioncharacteristicsbetweenNTPsandthatdonotincludeswitchingfunctionsthattheusercancontrol,(e.g.on-demandswitching)multiframe:sequenceoftwoSMFscontainingthemultiframealignmentword(seeannexC)NetworkTerminationPoint(NTP):physicalconnectionsandtheirtechnicalaccessspecificationswhichformpartofthepublictelecommunicationsnetworkandarenecessaryforaccesstoandefficientcommunicationthroughthatpublicnetworkPRBS(215-1):PseudoRandomBitSequence(PRBS)(asdefinedinclause2.1ofITU-TRecommendationO.151[3])Sabits:bits4to8(bitsSa4toSa8)inframesnotcontainingtheframealignmentsignal(seeannexC)Sub-Multiframe(SMF):sequenceof8frames,eachof256bits,overwhichtheCRC-4iscalculated(seeannexC)terminalequipment:equipmentintendedtobeconnectedtothepublictelecommunicationsnetwork,i.e.:-tobeconnecteddirectlytotheterminationofapublictelecommunicationnetwork;or-tointerworkwithapublictelecommunicationsnetworkbeingconnecteddirectlyorindirectlytotheterminationofapublictelecommunicationsnetwork,inordertosend,process,orreceiveinformation.3.2AbbreviationsForthepurposesofthepresentdocument,thefollowingabbreviationsapply:AISAlarmIndicationSignalAMIAlternateMarkInversionCRC-4CyclicRedundancyCheck-4bitD2048S2048kbit/sdigitalstructuredleasedlinedcdirectcurrentEMCElectroMagneticCompatibilityHDB3HighDensityBipolarcodeoforder3(seeannexB)ISDNIntegratedServicesDigitalNetworkNTPNetworkTerminationPointONPOpenNetworkProvisionppmpartspermillionPRBSPseudoRandomBitSequenceRAIRemoteAlarmIndicationrmsrootmeansquareRTRequirementsTableRXRXisasignalinput(ateithertheterminalequipmentinterfaceorthetestequipment,seefigure1)SDHSynchronousDigitalHierarchySMFSub-MultiFrameTXTXisasignaloutput(ateithertheterminalequipmentinterfaceorthetestequipment,seefigure1)UIUnitIntervalSIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)94RequirementsTheterminalequipmentinterfaceisforusewith2048kbit/sstructuredleasedlinesthatprovidebi-directional,point-to-pointdigitalconnectionswithaninformationtransferrateof1984kbit/swithoutrestrictiononbinarycontent.Anystructuringofthedatawithinthetransparent1984kbit/spartoftheframeistheresponsibilityoftheuser.4.1PhysicalcharacteristicsCurrentlynostandardizedconnectorisreadilyavailable.Consequently,theonlymethodofconnectionthatcanbespecifiedinthepresentdocumentistheuseofsolidconductorsof0,4mmto0,6mm.Thepresentdocumentrequirestheterminalequipmenttobecapableofpresentingeitherapointfortheattachmentofunterminatedsolidconductors,orsolidconductorsthemselves(seeclause4.1.1).Itisarequirementthatsuchaconnectionmethodbeavailabletobeprovidedforusewiththeterminalequipmentifnecessary.Inordertoallowconnectiontobemadeusingothermethods(e.g.connectors),theterminalequipmentispermittedtobesuppliedwithaconnectionmethodsuitableforusewiththosemethods(seeclause4.1.2).NOTE1:Thefollowingareexamplesofarrangementsthatcomplywiththerequirements.Thelistbelowshouldnotberegardedasanexhaustivelistofallpermittedarrangements:a)acord,permanentlyconnectedtotheterminalequipmentatoneendandunterminatedattheotherend,withwiresthataresolidconductorswithdiametersintherange0,4mmto0,6mm;b)acord,connectedviaaplugandsockettotheterminalequipmentatoneendandunterminatedattheotherend,withwiresthataresolidconductorswithdiametersintherange0,4mmto0,6mm;c)aninsulationdisplacementconnector,designedtoacceptwireswithsolidconductorswithdiametersintherange0,4mmto0,6mm,butwithnocord;d)ascrewconnector,designedtoacceptwireswithsolidconductorswithdiametersintherange0,4mmto0,6mm,butwithnocord;e)thearrangementinb)plusoneormoreadditionalalternativecordswiththesameplugorsocketarrangementattheterminalendandanyplugorsocketattheotherend;f)thearrangementinc)ord)plusoneormorecordssuitableforconnectiontotheterminalequipmentatoneendandanyplugorsocketattheotherend.Thetransmitpairistheoutputfromtheterminalequipmentinterface.Thereceivepairistheinputtotheterminalequipmentinterface,asshowninfigure1.Wheretheterms"output"and"input"areusedwithoutqualificationinthepresentdocument,theyrefertotheterminalequipmentinterface.NetworkInterfaceTXRXRXTXTerminalEquipmentOutputInputOutputInputFigure1NOTE2:TheuseofashieldedcordorcablemaybenecessarytomeetradiationandimmunityrequirementsdefinedinElectroMagneticCompatibility(EMC)standards.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)104.1.1HardwiredconnectionRequirement:theterminalequipmentshallprovide:a)asetofconnectioncontacts(e.g.aninsulationdisplacementconnectororascrewterminalblock)towhichsolidwireconductorswithdiametersintherange0,4mmto0,6mmmaybeconnected;orb)awiringarrangementconnectedbyanymeanstotheterminalequipment,withunterminatedsolidwireconductorswithdiametersintherange0,4mmto0,6mmattheenddistantfromtheterminalequipment.Test:thereisnotest.Allsubsequenttestsarecarriedoutviathespecifiedconnectionmethod.4.1.2AlternativemeansofconnectionAnyalternativemeansofconnectionmaybeprovidedinadditiontotheconnectionarrangementsunderclause4.1.1.4.2Electricalcharacteristics4.2.1Outputport4.2.1.1SignalcodingRequirement:thesignaltransmittedattheoutputportshallcomplywiththeHighDensityBipolarcodeoforder3(HDB3)encodingrules(seeannexB).Test:thetestshallbeconductedaccordingtoclauseA.2.1.4.2.1.2WaveformshapeRequirement:thepulseattheoutputportshallcomplywiththerequirementsgivenintable1andfigure2,basedonITU-TRecommendationG.703[1].Table1:WaveformshapeatoutputportPulseshape(nominallyrectangular)Allmarksofavalidsignalshallconformtothemask(seefigure2)irrespectiveofthepolarity.ThevalueVcorrespondstothenominalpeakvoltageofamark.Testloadimpedance120Ωnon-reactiveNominalpeakvoltageVofamark3VPeakvoltageofaspace0±0,3VNominalpulsewidth244nsRatiooftheamplitudesofpositiveandnegativepulsesatthecentreofthepulseinterval0,95to1,05Ratioofthewidthsofpositiveandnegativepulsesatthenominalhalfamplitude0,95to1,05SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)11269ns194ns(244-50)V=100%50%0%10%10%10%10%20%244ns219ns(244-25)488ns(244+244)Nominalpulse20%20%10%10%(244+25)Figure2:Pulsemaskfor2048kbit/spulseTest:thetestshallbeconductedaccordingtoclauseA.2.2.4.2.1.3OutputtimingThisrequirementissuchthattheterminalequipmentiscapableofoperatingwhenconnectedtoleasedlinescapableofcarryingusertimingwithintherange2048kbit/s±50partspermillion(ppm)andwhenconnectedtoleasedlinesthatprovidetimingthatissynchronoustothenetworktiming.ForfurtherinformationseeannexE.Requirement:theterminalequipmentshallhave:a)aninternalclockwhichshallprovideabitrateattheoutputportwithinthelimitsof2048kbit/s±50ppm;andb)thecapabilitytoprovideaclockloopsuchthatthesignaltimingattheoutputportisderivedfromthetimingattheinputport.Theterminalequipmentmayalsohave:c)anexternalreferencesignalinputfromwhichtheoutputtimingmaybederived.Test:forcasea)thetestshallbeconductedaccordingtoclauseA.2.3.Thecapabilitytoprovideaclockloop,caseb),andthederivationofaclocksignalfromanexternalreferencesignalinput,casec),arecoveredbythetestofclauseA.2.8.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)124.2.1.4ImpedancetowardsgroundRequirement:wheretheterminalequipmenthasaground,theimpedancetowardsgroundoftheoutputportshallbegreaterthan1000Ωforfrequenciesintherange10Hzto1MHzwhenmeasuredwithasinusoidaltestvoltageof2Vrootmeansquare(rms).Forthepurposeofthisrequirement,groundshallbetheterminalequipmentcommonreferencepointortestreferencepoint.NOTE:Thisrequirementisincludedtoallowtransformerlessimplementations.Test:thetestshallbeconductedaccordingtoclauseA.2.7.4.2.1.5OutputjitterRequirement:thepeak-to-peakoutputjittershallnotexceedthelimitsoftable2whenmeasuredwithabandpassfilterwithlinearcut-offwiththedefinedcut-offfrequencies.Atfrequenciesbelowthelower3dBpoint,theattenuationofthehighpassfiltershallrisewithavalueequalto20dBperdecade.Atfrequenciesabovetheupper3dBpoint,theattenuationofthelowpassfiltrationshallrisewithavaluegreaterthan,orequalto,60dBperdecade.Forthepurposeoftesting,anysignalinputfromwhichtheoutputtimingisderivedshallbeprovidedwiththemaximumtolerableinputjitter,andwiththemaximumtolerableinputfrequencydeviation,asspecifiedbythemanufacturer.Wheretheoutputtimingoftheterminalequipmentistakenfromtheleasedline,theinputtotheterminalequipmentshallbeprovidedwithcomponentsofsinusoidaljitteratpointsonthecurveoffigure3andtable4.NOTE:Aseparaterequirementforoutputjitteratfrequenciesbelow40Hzisnotrequiredbecausethemeasurementfilterwithafirstorderlowercut-offwillallowthejittertohaveaspectrumwhoseamplituderisesat20dB/decadeasthefrequencyreducesbelow40Hz.Wheretimingistakenfromtheleasedline,thetestusesinputjitterfrequenciesfrom20Hzupwards.Table2:MaximumoutputjitterMeasurementfilterbandwidthOutputjitterLowercut-off(highpass)Uppercut-off(lowpass)UnitInterval(UI)peak-to-peak(maximum)40Hz100kHz0,11UITest:thetestshallbeconductedaccordingtoclauseA.2.8.4.2.1.6OutputreturnlossTherearenorequirementsforoutputreturnlossunderthepresentdocument.NOTE:Arequirementforoutputreturnlossmaybeaddedtothepresentdocumentwhenappropriatespecificationsbecomeavailable.4.2.1.7OutputsignalbalanceTherearenorequirementsforoutputsignalbalanceunderthepresentdocument.NOTE:TheeffectsoftheoutputsignalimbalancearecoveredundertheEMCDirective(89/336/EEC).4.2.1.8OutputstructureRequirement:thebitstreamtransmittedattheoutputoftheterminalequipmentshallbestructuredasdefinedinclauseC.1.Test:thetestshallbeconductedaccordingtoclauseA.2.9.1.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)134.2.1.8.1CRC-4Requirement:theCRC-4bitstransmittedattheoutputoftheterminalequipmentshallbeasdefinedintablesC.1andC.2andclauseC.2.1ofannexCandshallcorrespondtothedatatransmittedattheoutputoftheterminalequipment.Test:thetestshallbeconductedaccordingtoclauseA.2.9.1.4.2.1.8.2UseoftheE-bitsTheterminalequipmentshallcomplyeitherwithclause4.2.1.8.2.1orclause4.2.1.8.2.2.4.2.1.8.2.1TerminalsnotusingtheE-bitsThisclauseisapplicabletothoseterminalequipmentswhichdonotusetheE-bitstoindicateerroredSMFs.Requirement:bothE-bitstransmittedattheoutputoftheterminalequipmentshallbesettobinaryONEinallinstances.Test:thetestshallbeconductedaccordingtoclauseA.2.9.2.4.2.1.8.2.2TerminalsusingtheE-bitstoindicateerroredSMFsThisclauseisapplicabletothoseterminalequipmentswhichusetheE-bitstoindicateerroredSMFs.Requirement:theE-bitstransmittedattheoutputoftheterminalequipmentshallindicateerroredSMFsintheinputbitstream.OneE-bitinamultiframeshallbesettobinaryZEROforeacherroredSMFreceivedintheinputbitstream.TheE-bitscorrespondingtonon-erroredSMFsshallbesettobinaryONE.AnydelaybetweenthedetectionofanerroredSMFandthesettingoftheE-bitthatindicatestheerroredSMFshallbelessthan1second.Test:thetestshallbeconductedaccordingtoclauseA.2.9.3.4.2.1.8.3UseoftheA-bitTheterminalequipmentshallcomplyeitherwithclause4.2.1.8.3.1orclause4.2.1.8.3.2.4.2.1.8.3.1TerminalsnotusingtheA-bitRequirement:theA-bittransmittedattheoutputoftheterminalequipmentshallbesettobinaryZEROinallinstances.Test:thetestshallbeconductedaccordingtoclauseA.2.9.4.4.2.1.8.3.2TerminalsusingtheA-bitRequirement:theA-bittransmittedattheoutputoftheterminalequipmentshallbesettobinaryZEROinnormaloperationbutmaybechangedfrombinaryZEROtobinaryONEwithin30msofanyofthefollowingconditionsoccurringintheinputbitstream:a)threeconsecutiveincorrectframealignmentsignals,(thecorrectframealignmentsignalisdefinedintableC.1);b)therebeing=915erroredSMFsoutof1000SMFs.TheterminalmayalsochangetheA-bitfrombinaryZEROtobinaryONEwithin30msof:c)bit2inframesnotcontainingtheframealignmentsignalbeinginerror(i.e.bit2isabinaryZERO)onthreeconsecutiveoccasions.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)14Foraterminalequipmentrecoveringfromlossofframealignment(i.e.theA-bitsettobinaryONE)theA-bittransmittedattheoutputoftheterminalequipmentshallbesetfrombinaryONEtobinaryZEROwithin30msofanyofthefollowingconditionsoccurringintheinputbitstream:d)forthefirsttime,thepresenceofthecorrectframealignmentsignal(asdefinedintableC.1);ande)theabsenceoftheframealignmentsignalinthefollowingframedetectedbyverifyingthatbit2ofthebasicframeisabinaryONE;andf)forthesecondtime,thepresenceofthecorrectframealignmentsignalinthenextframe.Test:thetestshallbeconductedaccordingtoclauseA.2.9.4.4.2.1.8.4UseoftheSabitsThereisnorequirementonthevalueorsettingoftheSabitsattheoutputoftheterminalequipment.4.2.2Inputport4.2.2.1SignalcodingRequirement:theinputportshalldecodewithouterrorHDB3encodedsignalsinaccordancewithHDB3encodingrules(seeannexB).Test:thetestshallbeconductedaccordingtoclauseA.2.6.4.2.2.2InputreturnlossRequirement:theinputreturnlosswithrespectto120Ωattheinterfaceshallbegreaterthanorequaltothevaluesgivenintable3,whichistakenfromclause9.3ofITU-TRecommendationG.703[1].Table3:InputportminimumreturnlossFrequencyrangeReturnloss51kHzto102kHz102kHzto2048kHz2048kHzto3072kHz12dB18dB14dBTest:thetestshallbeconductedaccordingtoclauseA.2.4.4.2.2.3InputlosstoleranceRequirement:theinputportshalldecodewithouterrorsa2048kbit/ssignalasdefinedinclauses4.2.1.1and4.2.1.2abovebutmodifiedbyacableorartificialcablewiththefollowingcharacteristics:a)attenuationthatfollowsa¹flawwithvaluesthroughouttherange0to6dBat1024kHz;andb)characteristicimpedanceof120Ωwithatoleranceof±20%inthefrequencyrangefrom200kHzupto,butnotincluding,1MHz,and±10%at1MHz.Test:thetestshallbeaccordingtoclauseA.2.5.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)154.2.2.4ImmunityagainstreflectionsRequirement:whenasignalcomprisingacombinationofanormalsignalandaninterferingsignalisappliedtotheinputport,viaanartificialcablewithalossintherange0dBto6dBat1MHz,noerrorsshallresultduetotheinterferingsignal.ThenormalsignalshallbeasignalencodedaccordingtoHDB3,shapedaccordingtothemaskoffigure2,withabinarycontentinaccordancewithaPRBS(215-1).Theinterferingsignalshallbethesameasthenormalsignalexceptthatthelevelisattenuatedby18dB,thebitrateiswithin2048kbit/s±50ppmandthetimingshallnotbesynchronizedtothenormalsignal.Test:thetestshallbeconductedaccordingtoclauseA.2.5.4.2.2.5TolerablelongitudinalvoltagesRequirement:thereceivershalloperatewithouterrorswithanyinputsignalinthepresenceofalongitudinalvoltageofmagnitude2Vrmsoverthefrequencyrange10Hzto30MHz.NOTE:Thisrequirementisincludedtoallowtransformerlessimplementations.Test:thetestshallbeconductedaccordingtoclauseA.2.6.4.2.2.6ImpedancetowardsgroundRequirement:wheretheterminalequipmenthasaground,theimpedancetowardsgroundoftheinputportshallbegreaterthan1000Ωforfrequenciesintherange10Hzto1MHzwhenmeasuredwithasinusoidaltestvoltageof2Vrms.Forthepurposeofthisrequirement,groundshallbetheterminalequipmentcommonreferencepointortestreferencepoint.NOTE:Thisrequirementisincludedtoallowtransformerlessimplementations.Test:thetestshallbeconductedaccordingtoclauseA.2.7.4.2.2.7InputjittertoleranceRequirement:theterminalequipmentshalltolerateatitsinputportthemaximuminputjitterasshownintable4andfigure3.NOTE:Terminalequipmentwithmorethanoneinputwillnormallyneedtobedesignedwithawanderbufferofatleast18µs,however,toaccommodatethewanderthatmaybeproducedbySynchronousDigitalHierarchy(SDH)networks,upto40µsmaybeneeded.Table4:InputjittertolerancePeak-to-peakamplitude(UI)Frequency(Hz)A1A2f1f2f3f41,50,220240018000100000SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)16peak-to-peakjitterpeak-to-peakjitterjitterfrequencyjitterfrequencyf1f1f2f2f3f3f4f4A1A1A2A2Figure3:InputjittertoleranceTest:thetestshallbeconductedaccordingtoclauseA.2.8.4.2.2.8InputclocktoleranceRequirement:theterminalequipmentshalldecodewithouterrorHDB3encodedsignalsoverthefrequencyrange2048kbit/s±50ppm.Test:thetestshallbeconductedinaccordancewithclauseA.2.8.4.2.2.9Inputframestructure4.2.2.9.1FramealignmentRequirement:theinputportshallacceptaninputbitstreamwithaframeandmultiframestructureasdefinedinannexC.Theterminalequipmentshallbecapableofachievingframealignmentinordertoseparatetheuserdatafromtheframeinformation.Framealignmentshallbeachievedfollowing:a)forthefirsttime,thepresenceofthecorrectframealignmentsignal;andb)theabsenceoftheframealignmentsignalinthefollowingframedetectedbyverifyingthatbit2ofthebasicframeisabinaryONE;andc)forthesecondtime,thepresenceofthecorrectframealignmentsignalinthenextframe,providedthatthedatadoesnotcontainanysimulatedframealignmentwords.Theterminalequipmentshallcontinuetomaintainframealignmentintheeventofreceivingoneortwoconsecutiveincorrectframealignmentsignals.Onreceiptofthreeconsecutiveincorrectframealignmentsignalstheterminalequipmentshallconsiderframealignmenttohavebeenlostandinitiateasearchforframealignment.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)17Framealignmentmayalsobeconsideredtohavebeenlostfollowing:d)theoccurrenceof=915erroredSMFsoutof1000SMFs;ore)bit2inframesnotcontainingtheframealignmentsignalbeinginerroronthreeconsecutiveoccasions;orf)theinabilitytoachievemultiframealignmentwithin8ms(seeclause4.2.2.9.2).Test:thetestshallbeconductedinaccordancewithclauseA.2.10.1.4.2.2.9.2MultiframealignmentThisrequirementisoptionalandappliesonlytothoseterminalequipmentsneedingtoobtainmultiframealignmentinordertoextractCRC-4informationinordertocomplywithclause4.2.1.8.2.2.Requirement:CRC-4multiframealignmentshallbeachievedifatleasttwovalidCRC-4multiframealignmentsignalscanbelocatedwithin8ms(thetimeseparatingtwoCRC-4multiframealignmentsignalsbeing2msoramultipleof2ms).Ifmultiframealignmentcannotbeachievedwithin8msitshallbeassumedthatframealignmentisduetoaspuriousframealignmentsignalandaresearchforframealignmentshallbeinitiated.NOTE:Theresearchforframealignmentshouldbestartedatapointjustafterthelocationoftheassumedspuriousframealignmentsignal.Thiswillusuallyavoidrealignmentontothespuriousframealignmentsignal.Test:thetestshallbeconductedinaccordancewithclauseA.2.10.2.4.3SafetyRequirementsforsafetyareoutsidethescopeofthepresentdocument.SafetystandardsarepublishedbyCENELEC.NOTE1:AnexampleofsuchaCENELECproductsafetystandardisEN60950(seeannexF).NOTE2:Forsafetycategoriesofinterfaces,seeEG201212.ThisdocumentisalsoavailablefromCENELECasROBT-002.NOTE3:Designersshouldtakeintoaccounttheminimumimpedancetowardsgroundspecifiedinthepresentdocument.4.4OvervoltageOvervoltageaspectsareoutsideofthescopeofthepresentdocument.4.5ElectroMagneticCompatibility(EMC)EMCrequirementsareoutsidethescopeofthepresentdocument.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)18AnnexA(normative):TestmethodsA.1GeneralThisannexdescribesthetestprinciplestodeterminethecomplianceofaterminalequipmentagainsttherequirementsofthepresentdocument.Itisoutsidethescopeofthepresentdocumenttoidentifythespecificdetailsoftheimplementationofthetests.Aterminalequipmentmaybedesignedforthrough-connectingandmayfulfiltheelectricalrequirementsonlyifthrough-connected.Inthesecasestherequirementsofthepresentdocumentarevalidandthetestsshallbecarriedoutwiththethrough-connectionterminatedasspecifiedbythemanufacturer.Detailsoftestequipmentaccuracyandthespecificationtoleranceofthetestdevicesarenotincludedinallcases.Wheresuchdetailsareprovidedtheyshallbecompliedwith,butthewaytheyareexpressedshallnotconstrainthemethodofimplementingthetest.NOTE:Attentionisdrawntotheissueofmeasurementuncertaintywhichmaybeaddressedinfuturedocuments.Notalltherequiredtestresultsmakeallowanceforspuriouseventsduringtesting(e.g.errorsduetoEMCeffects),whichmaymakeitnecessarytorepeatatest.Thetestconfigurationsgivendonotimplyaspecificrealizationoftestequipmentortestarrangement,ortheuseofspecifictestdevicesforconformancetesting.However,anytestconfigurationusedshallprovidethosetestconditionsspecifiedunder"interfacestate","stimulus"and"monitor"foreachindividualtest.Thetestequipmentshallbeadevice,oragroupofdevices,thatiscapableofgeneratingastimulussignalconformingtothepresentdocumentandcapableofmonitoringthesignalreceivedfromtheinterface.A.1.1AdditionalinformationtosupportthetestThefollowingfacilitiesshallbeprovidedbytheterminalequipmentinterfaceundertest:a)anabilitytoconfiguretheterminalequipmentsuchthatitprovidesatransparentloopbackoftheinputtotheoutput;andb)anabilitytotransmitagivenbitpattern,e.g.PRBS(215-1),withinthe1984kbit/suserchannel.Wherea)orb)cannotbeprovided,theterminalequipmentsuppliershallprovideanalternativemeansofperformingthetest.NOTE:WhereterminalsequipmentsusetheE-bitstoindicateerroredSMFs,thismaybeusedasanalternativetoatransparentloopbackinordertodetermineifdataattheinputhasbeencorrectlyreceived.A.1.2EquipmentconnectionThetestsinthepresentdocumentshallbecarriedoutusingtheconnectionmethodsuitableforusewithunterminatedsolidconductorsasdefinedinclause4.1.1.However,inthecaseofthetestsspecifiedinclausesA.2.2,A.2.4andA.2.7,analternativemethodofconnectionmaybeprovidedbytheterminalequipmentsupplierfortestpurposes.Inthiscase,thismethodofconnectionshallbeusedforthesetestsbecausetherequirementconsidersanywiringtobepartoftheinstallationcabling.NOTE:ThisalternativemethodofconnectionisfortestpurposesonlyandhasbeenintroducedbecausethecharacteristicstestedinclausesA.2.2,A.2.4andA.2.7arebasedonITU-TRecommendationG.703[1]whichmakesnoallowanceforadditionalwiring.Thisalternativemethodmaynotbethesameasthealternativemethodofconnectionreferredtoinclause4.1whichisforoperationaluse.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)19A.2TestmethodsOnetestmaycovermorethanonerequirement.Thescopeofeachtestisdefinedundertheheading"purpose".A.2.1SignalcodingattheoutputportPurpose:toverifythatthesignalcodingattheterminalequipmentoutputportcomplieswiththeHDB3codingrulesasrequiredbyclause4.2.1.1.Testconfiguration(seefigureA.1):TestEquipmentTXRXRXTXTerminalEquipmentFigureA.1:SignalcodingInterfacestate:powered.Stimulus:theterminalequipmentshalltransmitaHDB3bitstreamaccordingtotheframestructureofannexC.Thebinarycontentofthedatacontainedinbits9to256oftheframeshallbeabitstreamincludingthesequences<0000><0000>and<0000><0000>,where0=spaceand1=markinputtotheHDB3encoder,(seenote).Monitor:theoutputbitstreamforatestperiodofsufficienttimetoallowtransmissionof100occurrencesoftheabovepatternsplusthelatencyperiodoftheerrordetectionmechanism.Results:thereshallbenoerrorsinthedecodedbitstream.NOTE:Apseudorandombitstream,e.g.PRBS(215-1),willbeacceptableifthebitpatternsoftheaboveclauseareincludedinthebitstream.A.2.2WaveformshapeatoutputportPurpose:toverifyconformanceoftheoutputwaveformshapewiththerequirementsofclause4.2.1.2.Testconfiguration(seefigureA.2):MeasuringEquipmentTTerminalEquipmentTXT=TerminatingResistor120Ω ± 0,25%FigureA.2:WaveformshapeatoutputportSIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)20Interfacestate:powered.Stimulus:undefined.Monitor:-marksandspacestransmittedbytheterminalequipment,measuringtheamplitudeandshapeofpositiveandnegativepulses(measuredatthecentreofthepulseinterval)andthetimedurationofpositiveandnegativepulses(measuredatthenominalhalfofthepulseamplitude,i.e.1,5V);-theoverallmeasurementaccuracyshallbebetterthan90mV.Allthemeasurementsshallbeperformedusingmeasuringequipmentcapableofrecordingdirectcurrent(dc).Abandwidthof200MHzorgreatershallbeusedtoensurethecaptureofoverorundershootofthepulse.Results:-bothpositiveandnegativepulsesshallbewithinthemaskoffigure2,whereV=100%shallbe3V;-thebitintervalcorrespondingtoaspaceshallnotpresentvoltageshigherthan±0,3V;-theratiobetweentheamplitudeofpositiveandnegativepulsesshallbecontainedintherangefrom0,95to1,05;-theratiobetweenthepulsewidthsofpositiveandnegativepulsesshallbeintherangefrom0,95to1,05.A.2.3OutputtimingPurpose:toverifythebitrateiswithinthelimitsof2048kbit/s±50ppmwhentheterminalequipmentisgeneratingtimingfromaninternalclock,clause4.2.1.3.Testconfiguration(seefigureA.3):-theterminalequipmentshallbeconfiguredtoprovideoutputtimingfromtheinternalclocksource.TheterminalequipmentoutputshallbeanyHDB3encodedbitstream.TerminalEquipmentTXTestEquipmentRXFrequencyCounterExtractedClockFigureA.3:OutputtimingInterfaceState:powered.Stimulus:undefined.Monitor:thebitratefromtheterminalequipmentoutputport.Results:thebitrateshallbewithinthelimitsof2048kbit/s±50ppm.SIST EN 300 420 V1.2.1:2004

ETSIETSIEN300420V1.2.1(2001-07)21A.2.4ReturnlossatinputportPurpose:toverifythatthereturnlossofthereceivepairoftheterminalequipmentinterfacecomplieswiththerequirementsofclause4.2.2.2.Testconfiguration(seefigureA.4):RXBridgeTGeneratorVoltmeterT=TerminatingResistor120Ω ± 0,25%TerminalEquipmentFigureA.4:ReturnlossatinputportInterfacestate:powered.Stimulus:sinusoidalsignalof3Vpeakattheinputtotheterminalequipmentwithafrequencyvariablebetween51kHzand3072kHz.Monitor:voltagemeasuredacrossthebridge,representingaterminatingresistorof120Ω,usingaselectivevoltmeterwithabandwidthoflessthan1kHz.Results:themeasuredreturnlossshallbegreaterthanorequaltothevaluesintable3ofclause4.2.2.2.NOTE:Thecharacteristicsofthegeneratorandofthevoltmetermaybedifferentdependingontheimplementationofthebridge,however,thetotalerrorofthetestset-upshouldbelessthan0,5dBintherangebetween10dBand20dB.Whenconnectedtoa120Ω±0,25%resistorthemeasuredreturnlossofthebridgeshouldbe20dBhigherthanthelimitsspecifiedfortheinterface.A.2.5InputlosstoleranceandimmunityagainstreflectionsPurpose:tochecktheinputportimmunityagainstaninterferingsignalcombinedwiththeinputsignal,asspecifiedinclause4.2.2.4,bothwithoutcable(i.e.0dBattenuationloss)andwithacableattenuationof6dB,asspecifiedinclause4.2.2.3.Testconfiguration(seefigureA.5):-theinterferingsignalshallbecombinedwiththemainsignalinacombiningnetworkofimpedance120Ω,withzerodBlossinthemainpathandanattenuationintheinterferencepathof18dB;-thecablesimulatorshallhaveanattenuationof6dBmeasuredat1024kHzandanattenuationcharacteristicthatfollowsa¹flawoverthefrequencyrange100kHzto10MHz;-theconformanceoftheinterfaceshallbeverifiedinthefollowingtestconditions:a)withoutcablesimulatorandwithoutinterferingsignal;andb)withcablesimulatorandwithoutinterferingsignal;andc)withoutcablesimulatorandwithinterferingsignal;andd)withcablesimulatorandwithinterferingsignal.-thetestshallberepeatedwiththewiresattheterminalequipmentinterfaceinput(RX)reversed.SIST EN 300 420
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