SIST-TP CLC/TR 50173-99-1:2008
Cabling guidelines in support of 10 GBASE-T
Cabling guidelines in support of 10 GBASE-T
This Technical Report a) specifies the transmission performance for channels to support 10 GBASE-T as specified in IEEE 802.3an, b) specifies the methods to assess whether installed Class E and Class F channels meet IEEE 802.3an requirements, c) provides mitigation techniques to improve the performance of an existing installation to meet the IEEE 802.3an requirements.
Verkabelungsleitfaden zur Unterstützung von 10 GBASE-T
Dieser Technische Bericht
a) legt das übertragungstechnische Leistungsvermögen für Übertragungsstrecken zur Unterstützung des in IEEE 802.3an spezifizierten 10 GBASE-T fest,
b) legt die Verfahren zur Bewertung installierter Übertragungsstrecken der Klasse E und Klasse F hinsichtlich der Einhaltung der Anforderungen von IEEE 802.3an fest,
c) bietet Abschwächungstechniken zur Verbesserung des Leistungsvermögens einer bestehenden Verkabelung, damit diese die Anforderungen von IEEE 802.3an einhält.
ANMERKUNG 1 Das in diesem Technischen Bericht festgelegte Leistungsvermögen der Übertragungsstrecke ist aus IEEE 802.3an abge¬leitet.
ANMERKUNG 2 IEEE 802.3an legt sowohl Anforderungen fest, die über den für EN 50173 1:2007, Klasse E, festgelegten Frequenz¬bereich hinausgehen, wie auch zusätzliche Parameter zu denjenigen für Klasse-E- und Klasse-F-Verkabelung in EN 50173-1:2007.
ANMERKUNG 3 Die Anforderungen für Übertragungsstrecken der Klasse E und Klasse F nach EN 50173 1:2007 legt dieser Technische Bericht nicht erneut fest.
Guide de câblage pour supporter le 10 GBASE-T
Vodila polaganja kablov za podporo 10 GBASE-T
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CLC/TR 50173-99-1:2008
01-maj-2008
Vodila polaganja kablov za podporo 10 GBASE-T
Cabling guidelines in support of 10 GBASE-T
Verkabelungsleitfaden zur Unterstützung von 10 GBASE-T
Guide de câblage pour supporter le 10 GBASE-T
Ta slovenski standard je istoveten z: CLC/TR 50173-99-1:2007
ICS:
33.040.50
35.110
SIST-TP CLC/TR 50173-99-1:2008 en,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL REPORT
CLC/TR 50173-99-1
RAPPORT TECHNIQUE
December 2007
TECHNISCHER BERICHT
ICS 35.110
English version
Cabling guidelines in support of 10 GBASE-T
Guide de câblage pour supporter Verkabelungsleitfaden zur Unterstützung
le 10 GBASE-T von 10 GBASE-T
This Technical Report was approved by CENELEC on 2007-11-02.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. CLC/TR 50173-99-1:2007 E
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CLC/TR 50173-99-1:2007 - 2 -
Foreword
This Technical Report was prepared by the Technical Committee CENELEC TC 215, Electrotechnical
aspects of telecommunication equipment.
The text of the draft was submitted to vote and was approved by CENELEC as CLC/TR 50173-99-1
on 2007-11-02.
This Technical Report provides guidance whether an installed generic cabling channel meeting the
requirements of EN 50173-1:2007, Class E, will support 10 GBASE-T as specified by IEEE 802.3an.
The Technical Report also provides mitigation procedures to improve the performance of Class E
channels to the point where the application is supported. Generic cabling channels meeting the
requirements of EN 50173-1:2007, Class F, will support IEEE 802.3an up to 100 m without mitigation.
The support of IEEE 802.3an includes additional parameters and an extended frequency range
beyond Class E. Conformance of installed cabling beyond the original cabling specifications must be
determined on a case-by-case basis, and is primarily needed due to new external noise requirements.
Whether these requirements are met by a specific channel is influenced by the components and
installation practices used. As IEEE 802.3an uses frequencies above those specified for Class E of
EN 50173-1:2007, input from supplier and installer may be helpful to evaluate the performance of
installed Class E channels.
This Technical Report takes into account the design goals for IEEE 802.3an (10 GBASE-T) equipment
such as:
a) frequency signal range up to 500 MHz;
b) meet EMC limits specified for EN 55022:2006, Class A;
NOTE While IEEE 802.3an specifies an application to meet Class A on unshielded cabling, meeting Class B may require
application specific equipment and/or cabling that exceeds the requirements of this TR respectively.
–12
c) support a bit error rate of 10 ;
d) support operation over four-connector, four-pair balanced cabling.
It is expected that IEEE 802.3an will be supported by the following cabling channels specified in
EN 50173-1:2007:
– Class F channels will support IEEE 802.3an to distances of at least 100 m;
– Class E channels using screened Category 6 components and assessed and mitigated according
to the guidelines in this Technical Report will support IEEE 802.3an over distances up to 100 m;
– Class E channels assessed and mitigated according to the guidelines in this Technical Report are
expected to support IEEE 802.3an over distances from 55 m up to 100 m using unscreened
Category 6 components.
In order to provide normative cabling specifications in explicit support of IEEE 802.3an, an amendment
to EN 50173-1:2007 is under consideration. This amendment will provide new channel specifications
that will include all characteristics needed to meet and/or exceed the IEEE 802.3an requirements
(Class E and Class F ).
A A
This Technical Report is derived from ISO/IEC TR 24750, which has been developed by
ISO/IEC JTC 1/SC 25 as a Technical Report Type 2.
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Contents
Introduction. 5
1 Scope. 7
2 Normative references . 7
3 Definitions and abbreviations. 7
3.1 Definitions . 7
3.2 Abbreviations. 9
4 Channel requirements. 9
4.1 General . 9
4.2 Return loss.10
4.3 Insertion loss .10
4.4 Near-end crosstalk loss (NEXT).11
4.5 Attenuation to crosstalk loss ratio near-end (ACR-N) .13
4.6 Attenuation to crosstalk loss ratio far-end (ACR-F).14
4.7 Alien (exogenous) crosstalk.16
4.8 Propagation delay.21
4.9 Delay skew.21
5 Guidance for mitigation.21
5.1 Planning certification, measurement and documentation.21
5.2 Mitigation techniques if in-channel parameters of the channel
from Clause 4 are not met .22
5.3 Mitigation techniques in case external parameters
of the channel (alien noise) from 4.7 are not met.22
Annex A (informative) Permanent link performance guidelines.24
Annex B (normative) Alien crosstalk margin computation.26
Annex C (informative) Analytical approach to alien crosstalk mitigation .31
Tables
Table 1 – Changes and additions to definitions in EN 50173-1:2007. 6
Table 2 – Equations for return loss limits for a channel .10
Table 3 – Return loss limits for a channel at key frequencies .10
Table 4 – Equation for insertion loss limits for a channel.11
Table 5 – Insertion loss limits for a channel at key frequencies .11
Table 6 – Equations for NEXT limits for a channel .11
Table 7 – NEXT limits for a channel at key frequencies .11
Table 8 – Equations for PSNEXT limits for a channel.12
Table 9 – PSNEXT limits for a channel at key frequencies.12
Table 10 – ACR-N limits for a channel at key frequencies.13
Table 11 – PSACR-N limits for a channel at key frequencies .14
Table 12 – Equation for ACR-F limits for a channel.15
Table 13 – ACR-F limits for a channel at key frequencies .15
Table 14 – Equation for PSACR-F limits for a channel.15
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Table 15 – PSACR-F limits for a channel at key frequencies.16
Table 16 – Equations for PSANEXT limits for a channel .17
Table 17 – PSANEXT limits for a channel at key frequencies.17
Table 18 – Equations for PSAACR-F limits for a channel.19
Table 19 – PSAACR-F limits for a channel at key frequencies and lengths .20
Table 20 – Examples of implementations at key insertion loss .20
Table 21 – Equations for propagation delay limits for a channel.21
Table 22 – Propagation delay limits for a channel at key frequencies.21
Table 23 – Delay skew limits for a channel .21
Table A.1 – Return loss for permanent link .24
Table A.2 – Insertion loss for permanent link .24
Table A.3 – NEXT for permanent link .25
Table A.4 – PSNEXT for permanent link.25
Table A.5 – ACR-F for permanent link .25
Table A.6 – PSACR-F for permanent link .25
Table B.1 – Power backoff schedule from main body IEEE 802.3 10 GBASE-T .26
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Introduction
In order to support IEEE 802.3 10 GBASE-T (ISO/IEC 8802-3:2000/A1, at present draft) over a
generic cabling systems as defined in series EN 50173, several new parameters are required to
specify the electrical transmission properties of the channel.
EN 50173-1 defines ACR and ELFEXT as: The S/N ratio of the noise in the disturbed pair to the signal
in the disturbing pair. The definition in EN 50173-1 is correct for cabling.
IEEE 802.3an defines these parameters slightly different: The S/N ratio of the noise in the disturbed
pair to the signal in the disturbed pair. This is of course the definition of importance for electrical
systems.
For equally long channels the values of both definitions are nearly the same, but if the channels have
different length the values based on IEEE 802.3an and EN 50173-1:2007 are different.
To align with IEEE 802.3an it was decided in February 2006 to change the naming and definition in
their cabling standard of some noise related items. The limits stay the same so backward compatibility
is assured (see Table 1 for summary).
Crosstalk and power sum crosstalk are well defined in EN 50173-1:2007. As cables are laid in trays,
ducts and/or are bundled together, the noise from one cable can couple into other cables. This can
happen between telecommunications cables of the same category, but also between cables with
different categories or even between signal or power line cables and telecommunications cables.
This type of noise is well known in telephony and existing versions of Ethernet over balanced cabling.
It has not been a major issue for the systems in use up to now. However, the increased frequency
range and sensitivity of the IEEE 802.3an transmission cannot neglect this external noise any more.
Only the power sum of the noise is of importance and is specified because it is irrelevant from which
external pairs or cables the noise is coming from and the noise from external sources cannot be
compensated for within the specific application addressed here. The power sum computation assumes
that the noise is generated by other channels using the same protocol. Disturbances that are created
by other protocols (like TV distribution) using the other channels are handled as background noise. To
determine alien crosstalk noise, the transmitter must therefore be known.
In a channel as specified in EN 50173-1, and measured in accordance with EN 50346, the near-end
(where the measurement transmitter is) and the far-end (were the measurement receiver is) are
known and the terms NEXT and FEXT are easy to define.
For alien crosstalk the term ANEXT or AFEXT can be ambiguous. Therefore new definitions for power
sum alien crosstalk noise (near-end and far-end) are introduced (see definitions). It appears that the
worst case situation is when a short channel runs in parallel at either end of a long channel. The short
channel with high signals will disturb the long channel receiver where receiving signals have been
attenuated due to the insertion loss of the long channel. For this case IEEE 802.3an introduced power
backoff strategies. The idea is that a system detects the length of the channel by receiving signal
amplitude and reduces the transmitter voltage to decrease alien noise.
IEEE 802.3an defines two limits for each of ANEXT and AFEXT that have to be met concurrently (for
values see 4.7.1):
a) The first limit applies to every pair individually within the disturbed channel;
b) The second limit applies to the average of all four pairs within the disturbed channel.
– PSANEXT average limit is 2,25 dB more stringent than the PSANEXT limit for each pair within
the disturbed channel;
– PSACR-F average is 4 dB more stringent than the PSACR-F limit for each pair within the
disturbed channel.
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If these two limits are not met concurrently tradeoffs can be calculated as explained in Annex B.
Table 1 – Changes and additions to definitions in EN 50173-1:2007
Term used in Term used in this Definition Requirement
EN 50173-1:2007 Technical Report
ACR ACR-N Revised No change
PSACR PSACR-N Revised No change
ELFEXT ACR-F Revised No change
PSELFEXT PSACR-F Revised No change
- PSANEXT New New
- PSAACR-F New New
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1 Scope
This Technical Report
a) specifies the transmission performance for channels to support 10 GBASE-T as specified in
IEEE 802.3an,
b) specifies the methods to assess whether installed Class E and Class F channels meet
IEEE 802.3an requirements,
c) provides mitigation techniques to improve the performance of an existing installation to meet the
IEEE 802.3an requirements.
NOTE 1 The channel transmission performance specified in this TR is derived from IEEE 802.3an.
NOTE 2 IEEE 802.3an specifies requirements beyond the frequency range specified for EN 50173-1:2007, Class E, and
additional parameters to those specified for Class E and Class F cabling in EN 50173-1:2007.
NOTE 3 This Technical Report does not re-specify the requirements for Class E and Class F channels of EN 50173-1:2007.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 50173-1:2007, Information technology – Generic cabling systems – Part 1: General requirements
EN 50346, Information technology – Cabling installation – Testing of installed cabling
1)
ISO/IEC 8802-3:2000/A1 , Information technology - Telecommunications and information exchange
between systems - Local and metropolitan area networks - Specific requirements – Part 3: Carrier
sense multiple access with collision detection (CSMA/CD) access method and physical layer
specifications - Media Access Control (MAC) parameters, physical layers, and management
parameters for 10 Gb/s operation
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this document the following terms and definitions apply in addition to those of
EN 50173-1.
3.1.1
alien crosstalk
the signal coupling from a disturbing pair of a channel to a disturbed pair of another channel
3.1.2
alien (exogenous) far-end crosstalk loss (AFEXT)
the signal isolation between a disturbing pair of a channel and a disturbed pair of another channel,
measured at the far-end
3.1.3
alien (exogenous) near-end crosstalk loss (ANEXT)
the signal isolation between a disturbing pair of a channel and a disturbed pair of another channel,
measured at the near-end
———————
1)
Under preparation.
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3.1.4
attenuation to alien (exogenous) crosstalk ratio at the far-end (AACR-F)
the difference, in dB, between the alien far-end crosstalk loss from a disturbing pair of a channel and
the insertion loss of a disturbed pair in another channel
3.1.5
attenuation to alien (exogenous) crosstalk ratio at the near-end (AACR-N)
the difference, in dB, between the alien near-end crosstalk loss from a disturbing pair of a channel and
the insertion loss of a disturbed pair in another channel
3.1.6
attenuation to crosstalk ratio at the far-end (ACR-F)
the difference, in dB, between the far-end crosstalk loss from a disturbing pair of a channel and the
insertion loss of a disturbed pair of the same channel
3.1.7
attenuation to crosstalk ratio at the near-end (ACR-N)
the difference, in dB, between the near-end crosstalk loss from a disturbing pair of a channel and the
insertion loss of a disturbed pair of the same channel
3.1.8
average alien (exogenous) near-end crosstalk loss
the calculated average of the alien near-end crosstalk loss of the pairs of a disturbed channel
3.1.9
average power sum alien (exogenous) near-end crosstalk loss
the calculated average of the power sum alien near-end crosstalk loss of the pairs of a disturbed
channel
3.1.10
average power sum attenuation to alien (exogenous) crosstalk ratio far-end
the calculated average of the power sum attenuation to alien crosstalk ratio at the far-end of the pairs
of a disturbed channel
3.1.11
equal level far end crosstalk ratio (ELFEXT)
the difference, in dB, between the far-end crosstalk loss from a disturbing pair of a channel and the
insertion loss of a disturbing pair of the same channel
3.1.12
power sum alien (exogenous) far-end crosstalk loss (PSAFEXT)
the power sum of the signal isolation between multiple disturbing pairs of one or more channels and a
disturbed pair of another channel, measured at the far-end
3.1.13
power sum alien (exogenous) near-end crosstalk loss (PSANEXT)
the power sum of the signal isolation between multiple disturbing pairs of one or more channels and a
disturbed pair of another channel, measured at the near-end
3.1.14
power sum attenuation to alien (exogenous) crosstalk ratio at the far-end (PSAACR-F)
the difference, in dB, between the power sum alien far-end crosstalk loss from multiple disturbing pairs
of one or more channels and the insertion loss of a disturbed pair in another channel
3.1.15
power sum attenuation to alien (exogenous) crosstalk ratio at the near-end (PSAACR-N)
the difference, in dB, between the power sum alien near-end crosstalk loss from multiple disturbing
pairs of one or more channels and the insertion loss of a disturbed pair in another channel
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3.1.16
power sum attenuation to crosstalk ratio at the far-end (PSACR-F)
the difference, in dB, between the power sum far-end crosstalk loss from multiple disturbing pairs of a
channel and the insertion loss of a disturbed pair in the same channel
3.1.17
power sum attenuation to crosstalk ratio at the near-end (PSACR-N)
the difference, in dB, between the power sum near-end crosstalk loss from multiple disturbing pairs of
a channel and the insertion loss of a disturbed pair in the same channel
3.1.18
power sum equal level far end crosstalk ratio (PSELFEXT)
the power sum of all disturbing pairs of a channel, of the difference, in dB, between the far-end
crosstalk loss and the insertion loss of each disturbing pair
3.2 Abbreviations
For the purposes of this document the following abbreviations apply in addition to those of
EN 50173-1:2007.
ACR-N Attenuation to crosstalk ratio near-end
ACR-F Attenuation to crosstalk ratio far-end
AFEXT Alien far-end crosstalk loss
ANEXT Alien near-end crosstalk loss
PSAFEXT Power sum alien far-end crosstalk loss
PSANEXT Power sum alien near-end crosstalk loss
PSAACR-F Power sum attenuation to alien crosstalk ratio far-end
4 Channel requirements
4.1 General
This clause discusses the IEEE 802.3an requirements in relation to the minimum performance of
Class E and Class F channels as specified in EN 50173-1:2007.
All requirements of this clause are met by EN 50173-1:2007, Class F.
To support IEEE 802.3an applications the channel performance limits of Class E of EN 50173-1 have
been extended here to higher frequencies and two new characteristics have been added:
a) PSANEXT (see 4.7.2)
b) PSAACR-F (see 4.7.3).
The parameters specified in this clause apply to channels with screened or unscreened cable
elements, with or without an overall screen, unless explicitly stated otherwise.
NOTE The term ”attenuation“ is used for definitions as it is common usage within the cabling industry. However, the correct
term is insertion loss which includes the effect of impedance variations both with and between the cabling components in the
channel.
For a balanced cabling installation to conform to this technical report:
1) the channel performance shall meet the requirements of this clause;
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2) the interfaces to the cabling shall conform to the requirements of Clause 8 of EN 50173 series of
standards with respect to mating interfaces;
3) local regulations concerning safety and EMC shall be met as applicable to the location of the
installation.
Measuring the link performance of an installed permanent link can be used to assess whether the
permanently installed cabling has the potential to be used as part of a balanced cabling channel to
support IEEE 802.3an. This assessment does not assure conformance to this Technical Report, and
shall not be used instead of the channel qualification procedure described in this clause. Annex A
contains balanced cabling permanent link performance guidelines.
4.2 Return loss
The variation of the input impedance of a channel is characterised by the return loss. To support
IEEE 802.3an the return loss for each pair of a channel shall meet the limits computed, to one decimal
place, using the formulae of Table 2. The limits shown in Table 3 are derived from the formulae at key
frequencies.
When required, the return loss shall be measured according to EN 50346. Terminations of 100 Ω shall
be connected to the cabling elements under test at the far-end of the channel. The return loss
requirements shall be met at both ends of the cabling.
Table 2 – Formulae for return loss limits for a channel
Frequency Minimum return loss
MHz dB
19,0
1 ≤ f < 10
10 ≤ f < 40 24-5lg(f)
40 ≤ f < 400 32-10lg(f)
6,0
400 ≤ f ≤ 500
Table 3 – Return loss limits for a channel at key frequencies
Frequency Minimum return loss
MHz dB
1,0 19,0
16,0 18,0
100,0 12,0
250,0 8,0
500,0 6,0
Values of return loss at frequencies for which the measured channel insertion loss is below 3,0 dB are
for information only.
4.3 Insertion loss
To support IEEE 802.3an, the insertion loss α of each pair of a channel shall not exceed the limits
computed, to one decimal place, using the formula of Table 4. The limits shown in Table 5 are derived
from the formula at key frequencies.
When required, the insertion loss shall be measured according to EN 50346.
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Table 4 – Formula for insertion loss limits for a channel
Frequency Maximum insertion loss
MHz dB
1 ≤ f ≤ 500
1,05()1,82 f + 0,0169 f + 0,25 f + 4 × 0,02 f
NOTE Values below 4 dB revert to 4 dB.
Table 5 – Insertion loss limits for a channel at key frequencies
Frequency Maximum insertion loss
MHz dB
1,0 4,0
16,0 8,3
100,0 21,7
250,0 35,9
500,0 53,4
See also 4.7 for insertion loss to alien crosstalk ratios.
4.4 Near-end crosstalk loss (NEXT)
4.4.1 Pair-to-pair NEXT
To support IEEE 802.3an the pair-to-pair NEXT α between each pair combination of a channel
NEXT
shall meet the limits computed, to one decimal place, using the formulae of Table 6. The limits shown
in Table 7 are derived from the formulae at key frequencies.
When required, the NEXT shall be measured according to EN 50346. The NEXT requirements shall
be met at both ends of the cabling.
Table 6 – Formulae for NEXT limits for a channel
Frequency Minimum NEXT
MHz dB
74,3−−15lg(ff) 94 20lg( )
−−20 20
1 ≤ f < 330 −+20lg 10 2× 10
31− 50lg( f / 330)
330 ≤ f ≤ 500
NOTE Values larger than 65 dB revert to 65 dB.
Table 7 – NEXT limits for a channel at key frequencies
Frequency Minimum NEXT
MHz dB
1,0 65,0
16,0 53,2
100,0 39,9
250,0 33,1
500,0 22,0
Values of NEXT at frequencies for which the measured channel insertion loss is below 4,0 dB are for
information only.
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4.4.2 Power Sum NEXT (PSNEXT)
To support IEEE 802.3an the PSNEXT α for each pair of a channel shall meet the limits
PSNEXT
computed, to one decimal place, using the formulae of Table 8. The limits shown in Table 9 are
derived from the formulae at key frequencies.
The PSNEXT requirements shall be met at both ends of the cabling.
PSNEXT of pair k, α (k) , is computed as follows:
PSNEXT
n
−×0,1 α (i,k )
NEXT
α (k) =−10× lg 10
(1)
PSNEXT ∑
ii=≠1, k
where
i is the number of the disturbing pair;
k is the number of the disturbed pair;
n is the total number of pairs;
α (i,k) is the near-end crosstalk loss coupled from pair i into pair k.
NEXT
Table 8 – Formulae for PSNEXT limits for a channel
Frequency Minimum PSNEXT
MHz dB
72,3−−15lg(ff) 90 20lg( )
−−20 20
−+20lg 10 2× 10
1 ≤ f < 330
28 − 42lg( f / 330)
330 ≤ f ≤ 500
NOTE Values larger than 62 dB revert to 62 dB.
Table 9 – PSNEXT limits for a channel at key frequencies
Frequency Minimum PSNEXT
MHz dB
1,0 62,0
16,0 50,6
100,0 37,1
250,0 30,2
500,0 20,4
Values of PSNEXT at frequencies for which the measured channel insertion loss is below 4,0 dB are
for information only
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4.5 Attenuation to crosstalk loss ratio near-end (ACR-N)
4.5.1 Pair-to-pair ACR-N
The ACR-N α for each pair combination of a channel shall meet the limits computed according to
ACR-N
Equation (2), to one decimal place. The limits shown in Table 10 are derived from the Equation (2) at
key frequencies. The requirement is automatically satisfied when both insertion loss and NEXT
requirements are met.
The ACR-N requirements shall be met at both ends of the cabling.
ACR-N of pairs i and k, α (i,k), is computed as follows:
ACR-N
α (i,k) = α (i,k) - α(k) dB (2)
ACR-N NEXT
where
i is the number of the disturbing pair,
k is the number of the disturbed pair,
α (i,k) is the near-end crosstalk loss coupled from pair i into pair k,
NEXT
α(k) is the insertion loss of disturbed pair k. When required, it shall be measured according to
EN 50346.
Table 10 – ACR-N limits for a channel at key frequencies
Frequency Minimum ACR-N
MHz dB
1,0 61
16,0 44,9
100,0 18,2
250,0 -2,8
500,0 -31,4
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4.5.2 Power sum ACR-N
...
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