SIST ETS 300 451:1999
(Main)Business TeleCommunications (BTC); Ordinary quality voice bandwidth 4-wire analogue leased line (A4O); Connection characteristics and network interface presentation
- Abstract
Specification of the public network side of the interface and the performance of the leased line service, including test procedures for compliance
- Status
- Published
- Publication Date
- 31-Oct-1999
- Technical Committee
- BTC - Business telecommunications
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Nov-1999
- Due Date
- 01-Nov-1999
- Completion Date
- 01-Nov-1999
- Mandate
- T-147-2
SIST ETS 300 451:1999 is the Slovenian adoption of ETS 300 451, a European Telecommunication Standard from ETSI. It specifies the public-network-side connection characteristics and network interface presentation for an ordinary quality voice bandwidth 4-wire analogue leased line (A4O), and it includes the test principles used to check conformance.
What does SIST ETS 300 451:1999 specify?
SIST ETS 300 451:1999 specifies the technical requirements and test principles for ordinary quality voice bandwidth 4-wire analogue leased lines provided as part of the ONP minimum set. It covers the network side of the interface at Network Termination Points (NTPs), the impairments allowed across the connection, and the physical and electrical presentation of the interface.
The standard is organized into four main clauses and five annexes:
| Part | What it covers |
|---|---|
| Annex A | Normative test methods for the connection and interface checks |
| Annex B | Informative method for weighted return loss calculation |
| Annex C | Informative background on overall loss and quantizing distortion |
| Annex D | Informative background on availability |
| Annex E | Bibliography |
The leased line is intended for the voice band from 300 Hz to 3 400 Hz, but the document also notes that other traffic can use the line if the service permits it. The tests are designed for bringing a line into service and returning it into service, not for testing while user traffic is being carried.
What are the key requirements of SIST ETS 300 451:1999?
Connection performance
- Overall loss - Clause 4.1.2 limits overall loss to the range 0 to 21 dB for a 1 020 Hz test signal at -13 dBm with 600 ohms termination at both ends. In practice, this tells the provider and the buyer what end-to-end attenuation the line must stay within.
- Loss/frequency distortion - Clause 4.1.3 sets frequency-dependent limits relative to 1 020 Hz across the voice band. This matters when the line must carry speech or other band-limited signals without uneven frequency response.
- Transmission signals - Clause 4.1.4 requires the line to carry a -13 dBm mean input signal in the voice band and a 0 dBm instantaneous peak signal. This is the practical check that normal voice signals and short peaks will pass without clipping.
- Transmission delay - Clause 4.1.5 limits one-way delay to a distance-based value for terrestrial paths and to 350 ms where satellite transmission is involved. This is important for speech quality and talker turn-taking.
- Random circuit noise - Clause 4.1.8 sets a psophometric noise limit, or an equivalent weighted-noise condition when output level is not declared. This matters because excess background noise reduces intelligibility.
Interface presentation and safety
- Return loss - Clause 4.2.3 requires return loss greater than 6 dB, or weighted return loss greater than 6 dB, over 300 Hz to 3 400 Hz. In practice, this controls impedance matching and helps reduce echo and signaling problems.
- Power feeding - Clause 4.2.4 says the network interface shall neither supply power to terminal equipment nor need power from it. That means the line interface must be passive from the terminal equipment point of view.
- Connector or hardwired presentation - Clause 4.2.1 specifies an 8-contact socket type from EN 28877 with defined contact assignments, while Clause 4.2.2 allows a hardwired presentation on request. This helps installers wire the interface correctly.
- Safety and overvoltage protection - Clauses 4.3 and 4.4 require compliance with TNV circuit safety provisions from EN 60950 and primary overvoltage protection according to national practice. This is the part that protects users, equipment, and the network.
What terms does SIST ETS 300 451:1999 define?
- Group delay - The propagation time through the leased line at a given frequency, expressed as the derivative of phase shift with respect to angular frequency.
- Group delay distortion - The difference between group delay at a given frequency and the minimum group delay in the band of interest.
- leased lines - Public-network telecommunications facilities that provide defined transmission characteristics between NTPs without user-controlled switching.
- Network Termination Point (NTP) - The physical network connection point and its technical access specification at the edge of the public network.
- reference impedance ZR - The 600 ohm impedance used as the reference for measurements and tests.
- voice bandwidth - The frequency band from 300 Hz to 3 400 Hz.
- Adaptive Differential Pulse Coded Modulation (ADPCM) - A digital speech coding method named in the distortion requirements and the quantizing distortion background.
Who uses SIST ETS 300 451:1999?
SIST ETS 300 451:1999 is used by leased line providers, public network operators, and test laboratories that need to verify analogue leased line interfaces. It is also relevant to terminal equipment designers and buyers who need to know how the network side of an A4O line is presented and what performance to expect.
Quality managers use it to define acceptance checks for line loss, delay, noise, return loss, and interface safety. Procurement teams use it to compare supplier offerings against a common technical description.
Which standards are used with SIST ETS 300 451:1999?
- EN 28877 - Provides the 8-contact connector type and contact assignment used for the socket presentation.
- EN 60950 - Provides the safety requirements for TNV circuits and electric shock protection.
- ITU-T Recommendation O.41 - Defines the psophometer used for random circuit noise measurements.
- ETS 300 453 - The directly related terminal equipment interface standard for ordinary and special quality voice bandwidth 4-wire analogue leased lines.
What does the SIST ETS 300 451:1999 document contain?
SIST ETS 300 451:1999 contains a requirements table, frequency-response limits, delay limits, noise limits, return-loss rules, and interface presentation rules. It also includes Annex A test set-ups for overall loss, loss/frequency distortion, delay, noise, maximum instantaneous power, return loss, and power feeding.
Annex B gives the weighted return loss method and calculation approaches, including an equation and an example calculation. Annex C explains how overall loss and quantizing distortion can arise in practical analogue leased lines, and Annex D explains availability terminology and assessment logic.
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Frequently Asked Questions
SIST ETS 300 451:1999 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Business TeleCommunications (BTC); Ordinary quality voice bandwidth 4-wire analogue leased line (A4O); Connection characteristics and network interface presentation". This standard covers: Specification of the public network side of the interface and the performance of the leased line service, including test procedures for compliance
Specification of the public network side of the interface and the performance of the leased line service, including test procedures for compliance
SIST ETS 300 451:1999 is classified under the following ICS (International Classification for Standards) categories: 33.040.50 - Lines, connections and circuits. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST ETS 300 451:1999 is associated with the following European legislation: Standardization Mandates: T-147-2. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
SIST ETS 300 451:1999 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.YPHVQLNBusiness TeleCommunications (BTC); Ordinary quality voice bandwidth 4-wire analogue leased line (A4O); Connection characteristics and network interface presentation33.040.50Vodi, zveze in tokokrogiLines, connections and circuitsICS:Ta slovenski standard je istoveten z:ETS 300 451 Edition 1SIST ETS 300 451:1999en01-november-1999SIST ETS 300 451:1999SLOVENSKI
STANDARD
EUROPEANETS 300 451TELECOMMUNICATIONFebruary 1996STANDARDSource: ETSI TC-BTCReference: DE/BTC-02031ICS:33.020Key words:ONP, leased line, A4OBusiness TeleCommunications (BTC);Ordinary quality voice bandwidth4-wire analogue leased line (A4O);Connection characteristics and network interface presentationETSIEuropean Telecommunications Standards InstituteETSI SecretariatPostal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.frTel.: +33 92 94 42 00 - Fax: +33 93 65 47 16Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1996. All rights reserved.SIST ETS 300 451:1999
Page 2ETS 300 451: February 1996Whilst 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 accuracy, please write to"ETSI Editing and Committee Support Dept." at the address shown on the title page.SIST ETS 300 451:1999
Page 3ETS 300 451: February 1996ContentsForeword.5Introduction.51Scope.72Normative references.73Definitions and abbreviations.83.1Definitions.83.2Abbreviations.84Requirements and tests.94.1Connection characteristics.94.1.1Tabulation of connection characteristics.94.1.2Overall loss.94.1.3Loss/frequency distortion.104.1.4Transmission signals.104.1.4.1Maximum mean input power.104.1.4.2Maximum instantaneous power.114.1.4.3Maximum power in a 10 Hz bandwidth.114.1.4.4Maximum input power outside the voice band.114.1.5Transmission delay.114.1.6Group-delay distortion.124.1.7Variation of overall loss with time.124.1.7.1Amplitude hits.124.1.7.2Other variations.124.1.8Random circuit noise.124.1.9Impulsive noise.124.1.10Phase jitter.124.1.11Distortion.124.1.11.1Quantizing distortion.124.1.11.2Total distortion.134.1.12Single tone interference.134.1.13Frequency error.134.1.14Harmonic distortion.134.2Interface presentation.134.2.1Connector specification.134.2.2Hardwired presentation.144.2.3Return loss.144.2.4Power feeding.144.3Safety.144.4Overvoltage protection.154.5ElectroMagnetic Compatibility (EMC).154.6Availability.15SIST ETS 300 451:1999
Page 4ETS 300 451: February 1996Annex A (normative):Test methods.16A.1General.16A.1.1Equipment connection.16A.1.2Reference impedance.16A.1.3Measurement frequency.16A.2Test Methods.16A.2.1Overall loss.16A.2.2Loss/frequency distortion and maximum mean input power.17A.2.3Transmission delay.18A.2.4Random circuit noise.19A.2.5Maximum instantaneous power.19A.2.6Return loss.20A.2.7Power feeding.21Annex B (informative):Weighted return loss measurements.23B.1Introduction.23B.2Weighting function.23B.2.1Calculation (trapezoidal rule).23B.2.2Calculation (tabulated data).24Annex C (informative):Overall loss and quantizing distortion.25C.1Introduction.25C.2Overall loss.26C.3Quantizing distortion.26Annex D (informative):Availability.28D.1General.28D.1.1Unavailability.28D.1.2Availability.28D.2Definition of unavailability periods.28D.3Availability figures.30Annex E (informative):Bibliography.31History.32SIST ETS 300 451:1999
Page 5ETS 300 451: February 1996ForewordThis European Telecommunication Standard (ETS) has been produced by the BusinessTeleCommunications (BTC) Technical Committee of the European Telecommunications StandardsInstitute (ETSI).This ETS resulted from a mandate from the Commission of the European Community (CEC) to provideharmonized standards for support of the Directive on Open Network Provision (ONP) of leased lines(92/44/EEC).There is another standard directly related to this ETS:ETS 300 453:"Business TeleCommunications (BTC); Ordinary and Special quality voicebandwidth 4-wire analogue leased lines (A4O and A4S); Terminal equipmentinterface".This ETS is based on information from ITU-T Recommendations and ETSI publications and the relevantdocuments are quoted where appropriate.Transposition datesDate of adoption of this ETS:2 February 1996Date of latest announcement of this ETS (doa):31 May 1996Date of latest publication of new National Standardor endorsement of this ETS (dop/e):30 November 1996Date of withdrawal of any conflicting National Standard (dow):30 November 1996IntroductionThe Council Directive on the application of ONP to leased lines (92/44/EEC), concerns the harmonizationof conditions for open and efficient access to, and use of, the leased lines provided over publictelecommunications networks and the availability throughout the European Union (EU) of a minimum setof leased lines with harmonized technical characteristics.The consequence of the Directive is that telecommunications organizations within the EU shall makeavailable a set of leased lines within and between points in these countries with specified connectioncharacteristics and specified interfaces. Under the Second Phase Directive (91/263/EEC) terminalequipment for connection to these leased lines will be required to fulfil certain essential requirements.CCITT Recommendation M.1040 (1988) is used as the basis for the connection characteristics.SIST ETS 300 451:1999
Page 6ETS 300 451: February 1996Blank pageSIST ETS 300 451:1999
Page 7ETS 300 451: February 19961ScopeThis European Telecommunication Standard (ETS) specifies the technical requirements and testprinciples for the connection characteristics and the physical and electrical characteristics of the networkinterface presentation of ordinary quality, voice bandwidth, 4-wire, analogue leased lines, provided as partof the minimum set under the Council Directive on the application of Open Network Provision (ONP) toleased lines (92/94/EEC).A connection is presented via interfaces at Network Termination Points (NTPs) and includes anyequipment that may provide the NTP. Signals between terminal equipments are subject to impairmentsduring their transfer over the connection. The limits to these impairments are stated in this ETS althoughin practice the overall performance may be considerably better.The leased line provides access to the voice bandwidth (300 Hz to 3 400 Hz) with no restrictions on theuse of the frequencies. The requirements of this standard have been chosen primarily for the transmissionof telephony although there is no restriction on the use of the leased line for other types of traffic.This ETS is applicable for leased lines, including part time leased lines, for which the establishment orrelease does not require any protocol exchange or other intervention at the NTP.The tests specified in this ETS cannot be carried out, nor can performance be monitored by the leasedline provider, while the leased line is in service, i.e. carrying user's traffic. Thus the tests are designed forbringing into and returning into service, although there is no obligation to perform these tests each timethe leased line is brought into or returned into service.The ETS covers the physical, mechanical and electrical characteristics of the network interface andspecifies the conformance tests for the connection characteristics and network interface. Some of thetests described in this ETS are not designed to be applied to the interface of an installed leased line; suchtests may be applied to equipment of the kind used to provide the interface.This ETS does not include details concerning the implementation of the tests nor does it includeinformation on any regulations concerning testing.2Normative referencesThis ETS incorporates by dated and undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listedhereafter. For dated references, subsequent amendments to or revisions of any of these publicationsapply to this ETS only when incorporated in it by amendment or revision. For undated references the latestedition of the publication referred to applies.[1]EN 28877 (1989): "Information processing systems - Interface connector andcontact assignments for ISDN basic access interface located at reference pointsS and T".[2]EN 60950 (1992): "Safety of information technology equipment includingelectrical business equipment".[3]ITU-T Recommendation O.41 (1993): "Psophometer for use on telephone-typecircuits".NOTE:This ETS also contains a number of informative references which have been includedto indicate the sources from which material has been derived, hence they do not havean associated normative reference number. Details of these publications are given inAnnex E. In some cases the same publication may have been referenced in both anormative and an informative manner.SIST ETS 300 451:1999
Page 8ETS 300 451: February 19963Definitions and abbreviations3.1DefinitionsFor the purposes of this ETS, the following definitions apply:group delay: A measure of the propagation time through the leased line. For a given frequency, it is equalto the first derivative of the phase shift through the leased line, measured in radians, with respect to theangular frequency measured in radians per second.group delay distortion: The difference between group delay at a given frequency and minimum groupdelay, in the frequency band of interest.leased lines: The telecommunications facilities provided by a public telecommunication network thatprovide defined transmission characteristics between network termination points and that do not includeswitching functions that the user can control, (e.g. on-demand switching).Network Termination Point (NTP): All physical connections and their technical access specificationswhich form part of the public telecommunications network and are necessary for access to and efficientcommunication through that public network.reference impedance ZR: This is 600 W. See also subclause A.1.2.terminal equipment: Equipment intended to be connected to the public telecommunication network; i.e.:-to be connected directly to the termination of a public telecommunication network; or-to interwork with a public telecommunication network being connected directly or indirectly to thetermination of a public telecommunication network,in order to send, process, or receive information.voice bandwidth: The band of frequencies over the range 300 Hz to 3 400 Hz.3.2AbbreviationsFor the purposes of this ETS, the following abbreviations apply:aReturn loss in dBaf()Return loss at frequency f in dBawWeighted return loss in dBAf()Return loss at frequency f expressed as a ratioA40Ordinary quality voice bandwidth 4-wire analogue leased lineADPCMAdaptive Differential Pulse Coded ModulationEMCElectroMagnetic CompatibilityffrequencyNTPNetwork Termination PointONPOpen Network Provisionqduquantizing distortion unitrmsroot mean squareRXReceive is a signal input (at either the leased line interface or the testequipment)TNVTelecommunications Network Voltage (see EN 60950 [2], subclause 3.4)TXTransmit is a signal output (at either the leased line interface or the testequipment)ZRReference impedanceSIST ETS 300 451:1999
Page 9ETS 300 451: February 19964Requirements and tests4.1Connection characteristicsThe ordinary quality voice bandwidth 4-wire analogue leased line is a bidirectional line, configured point-to-point, nominally covering the voice bandwidth. The connection is, in general, symmetrical, i.e. eachdirection of transmission has the same nominal characteristics, although the actual values areindependent.4.1.1Tabulation of connection characteristicsThe parameters defining the characteristics of the connection are given in table 1. These characteristicsdefine the service offered.Table 1: Network performance characteristicsDescriptionNatureReferencesubclauseOverall loss0 £ overall loss £ 21 dB4.1.2Loss/frequency distortionTable 2, figure 14.1.3Transmission signals- maximum mean input power- maximum instantaneous power- signal power in a 10 Hz bandwidth- maximum input power outside voice band-13 dBm0 dBmno requirementno requirement4.1.44.1.4.14.1.4.24.1.4.34.1.4.4Transmission delay- terrestrial (for distance G in kilometres)- via satellite< (15 + 0,01 G) ms< 350 ms4.1.5Group delay distortionno requirement4.1.6Variation of overall loss with time- amplitude hits- other variationsno requirement± 4 dB of that at 1 020 Hz4.1.74.1.7.14.1.7.2Random circuit noise< -41 dBm0p (see note)4.1.8Impulsive noiseno requirement4.1.9Phase jitterno requirement4.1.10Total distortion- quantizing distortion- total distortion£ 7,5 qdu; £ 1 ADPCM systemno requirement4.1.114.1.11.14.1.11.2Single tone interferenceno requirement4.1.12Frequency errorno requirement4.1.13Harmonic distortionno requirement4.1.14NOTE:Where the output relative level is not defined, an alternative value is specified in thereference subclause.4.1.2Overall lossRequirement: The overall loss, including long term variations, presented to a signal frequency of1 020 Hz sent at a power of -13 dBm in each direction of transmission with the line terminated in 600 W ateach end, shall be in the range:0 £ overall loss £ 21 dB.NOTE:The overall loss in each direction can be different.Test: The test shall be conducted according to subclause A.2.1.SIST ETS 300 451:1999
Page 10ETS 300 451: February 19964.1.3Loss/frequency distortionRequirement: The overall loss relative to that defined in subclause 4.1.2 above for the connection,presented to a signal sent at a power level of -13 dBm with the line terminated in 600 W at each end, shalllie between the limits given in table 2 and figure 1.Below 400 Hz and above 3 600 Hz, the relative loss shall not be less than -4 dB and 0 dB respectively, butis otherwise unspecified.Table 2: Limits for loss of the circuit relative to that at 1 020 HzUpper limitLower limitPoint(see fig. 1)Frequency HzRelative loss dBPoint(see fig. 1)Frequency HzRelative loss dBA4009E400-4B2 0009F300-3C2 00016G3 600-3D2 80016H3 60003002000Frequency Hz40036000916-32800ABCDGHRelative loss dB1020-4EFFigure 1: Limits for loss of the circuit relative to that at 1 020 HzTest: The test shall be conducted according to subclause A.2.2.4.1.4Transmission signals4.1.4.1Maximum mean input powerRequirement: The leased line shall be capable of carrying any signal presented at the input at a oneminute mean power level of -13 dBm within a voice bandwidth of 300 Hz to 3 400 Hz with the lineterminated in 600 W at each end.Test: The test shall be conducted according to subclause A.2.2.SIST ETS 300 451:1999
Page 11ETS 300 451: February 19964.1.4.2Maximum instantaneous powerRequirement: The leased line shall be capable of carrying a signal at the input having a maximum valueequal to an instantaneous power which is 13 dB above the mean value of -13 dBm (i.e. 0 dBm).NOTE:This value is based upon a provisional ITU-T value. See CCITT Recommendation V.2.Test: The test shall be conducted according to subclause A.2.5.4.1.4.3Maximum power in a 10 Hz bandwidthThere is no requirement for maximum power in a 10 Hz bandwidth.NOTE:However, there is a corresponding requirement on the terminal equipment specified inETS 300 453.4.1.4.4Maximum input power outside the voice bandNOTE:The leased line interface is not suitable for the handling of signals below 300 Hz andabove 3 400 Hz. Out of band signals from the terminal equipment are limited to avoidtrouble in the network (see terminal equipment interface requirement in ETS 300 453).4.1.5Transmission delayRequirement: The requirement depends upon whether satellite transmission is involved in the connectionor not:a)for connections where satellite transmission is not involved the one way end-to-end delayshall be less than (15 + 0,01 G) ms, where G is the geographical distance in kilometres, asshown in figure 2; orb)for connections where satellite transmission is involved the one way end-to-end delay shallbe less than 350 ms.NOTE:Requirements a) and b) are based on subclauses 2.2 and 2.3 of ITU-TRecommendation G.114 with suitable adjustment to requirement a) to allow for
thepossible use of loaded cable.Delay (ms)Geographical distance (km)100090003000600010015Figure 2: Upper limit of delayTest: The test shall be conducted according to subclause A.2.3.SIST ETS 300 451:1999
Page 12ETS 300 451: February 19964.1.6Group-delay distortionThere is no requirement for group delay distortion.NOTE:Group delay distortion is not considered to be important for voice communication.Terminal equipment for other purposes which wish to make use of leased linesconforming to this ETS will need to compensate for possible shortcomings due togroup delay distortion.4.1.7Variation of overall loss with time4.1.7.1Amplitude hitsThere is no requirement for amplitude hits.NOTE:Phase or amplitude hits are defined as sudden positive or negative changes in phaseor amplitude of an observed test signal which exceed a specified threshold and persistfor a period of time greater than a specified duration.4.1.7.2Other variationsRequirement: For a particular implementation, variations with time of the overall loss at 1 020 Hz(including daily and seasonal variations but excluding amplitude hits) shall not exceed ± 4 dB variationfrom the value established by the test for overall loss, see subclause 4.1.2. Any such variation shall notresult in an overall loss greater than the maximum specified in subclause 4.1.2.Test: There is no test for this but the record of the results of successive tests of overall loss may be usedto check compliance. The test shall be conducted according to subclause A.2.1.4.1.8Random circuit noiseRequirement: The level of the psophometric noise power at the output of the leased line shall be lessthan -41 dBm0p. In order that this parameter can be tested, the leased line provider should declare theplanned value of the output relative level of the leased line.Where the output relative level either is not, or cannot be, declared by the leased line provider, thepsophometrically weighted random circuit noise level shall be 28 dB below a received test signal which issent at a level of -13 dBm at a frequency of 1 020 Hz into the far end of the leased line.Test: The test shall be conducted according to subclause A.2.4.4.1.9Impulsive noiseThere is no requirement for impulsive noise.4.1.10Phase jitterThere is no requirement for phase jitter.4.1.11Distortion4.1.11.1Quantizing distortionRequirement: The quantizing distortion shall not exceed 7,5 quantizing distortion unit (qdu). Moreover,within this limit, no more than one Adaptive Differential Pulse Coded Modulation (ADPCM) system shall beused.Test: There is no test. This requirement shall be checked by calculation using information from thenetwork plans.SIST ETS 300 451:1999
Page 13ETS 300 451: February 19964.1.11.2Total distortionThere is no requirement for total distortion.4.1.12Single tone interferenceThere is no requirement for single tone interference.4.1.13Frequency errorThere is no requirement for frequency error.4.1.14Harmonic distortionThere is no requirement for harmonic distortion.4.2Interface presentationThe physical connection arrangements shall normally be by a socket as specified in subclause 4.2.1;however at the specific request of the user the connection arrangements specified in subclause 4.2.2 shallbe provided.4.2.1Connector specificationRequirement: The network interface shall provide an 8-contact socket of the type specified inEN 28877 [1] and with contact assignments as specified in table 3.Table 3: Contact assignmentContactNetwork interface1Unused2Unused3 & 6Receive pair4 & 5Transmit pair7Unused8UnusedNOTE:The transmit pair is the output from the network interface. The receive pair is the input tothe network interface as shown in figure 3. Where the terms "output" and "input" are usedwithout qualification in this ETS, they refer to the network interface.TXRXRXTXTERMINALEQUIPMENTINTERFACENETWORKINTERFACEOUTPUTINPUTINPUTOUTPUTFigure 3: Leased line configuration conventionsTest: There shall be a visual inspection that the socket is of the correct type. The contact assignments aretested indirectly through the tests in annex A.SIST ETS 300 451:1999
Page 14ETS 300 451: February 19964.2.2Hardwired presentationRequirement: The network interface shall provide a set of connection contacts (e.g. an insulationdisplacement connector or a screw terminal block) to which solid conductors with wire diameters in therange 0,4 to 0,6 mm may be connected. The leased line provider shall provide information on theconfiguration of the connection contacts used for each leased line interface.Test: There shall be a visual inspection that the connection method provided is suitable for taking solidconductors as defined in the requirement and that information on the configuration is provided.NOTE:All subsequent tests are carried out via the appropriate connection method.4.2.3Return lossRequirement: The return loss presented by the network interface against the reference impedance, whenthe far end interface of the connection is terminated by the reference impedance, shall either be:-greater than 6 dB over the frequency range 300 Hz to 3 400 Hz when measured with a voltageequivalent to a signal power level at the input to the leased line of -13 dBm at 1 020 Hz; or-if the return loss is not greater than 6 dB at all frequencies, then the weighted return loss against thereference impedance shall be greater than 6 dB over the frequency range 300 Hz to 3 400 Hz,when measured with a voltage equivalent to a signal power at the input to the leased line of-13 dBm at 1 020 Hz.The weighted return loss aw shall be given by:aAffdfw=-òéëêêêêùûúúúú385103003400,log()dBwhereAfaf()()=-1010andaf() is the measured return loss at frequency f expressed in dB.Test: The test shall be conducted according to subclause A.2.6.4.2.4Power feedingRequirement: The network interface shall not feed power to the terminal equipment interface and shallnot require power from the terminal equipment interface.Test: The test for power output from the network interface shall be conducted according to subclauseA.2.7. The test for the requirement not to support power feeding from the terminal interface is testedindirectly through the various tests of annex A since no powe
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