IEC TR 61156-1-3:2011

IEC/TR 61156-1-3 ®
Edition 1.0 2011-04
TECHNICAL
REPORT
colour
inside
Multicore and symmetrical pair/quad cables for digital communications –
Part 1-3: Electrical transmission parameters for modelling cable assemblies
using symmetrical pair/quad cables

IEC/TR 61156-1-3:2011(E)
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IEC/TR 61156-1-3 ®
Edition 1.0 2011-04
TECHNICAL
REPORT
colour
inside
Multicore and symmetrical pair/quad cables for digital communications –
Part 1-3: Electrical transmission parameters for modelling cable assemblies
using symmetrical pair/quad cables

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 33.120.20 ISBN 978-2-88912-429-9

– 2 – TR 61156-1-3  IEC:2011(E)
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions, symbols, units and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Symbols, units and abbreviated terms . 6
4 Traditional length correction formulae . 7
4.1 Introduction . 7
4.2 Length correction formulae in IEC 61156-1 . 7
4.3 The development of the traditional cross-talk length correction formulae
NEXT and EL FEXT [3] . 8
5 Using traditional cross-talk length correction formulae . 16
5.1 Background (see [4]) . 16
5.2 Example (see [5], [6]) Length and frequency dependency of direct near-end
crosstalk attenuation . 17
6 On length concatenation of measured cables, using scattering and scattering
transfer parameters, see informative reference [7]. . 21
7 Matrix (model) status, comparison of different calculations [8] . 24
8 Recommendations for applying length correction formulae to modelling cross-talk
in cable assemblies . 25
Bibliography . 26

Figure 1 – Coupling between two circuits due to unbalances of the primary parameters . 9
Figure 2 – Integration of the coupled near- and far-end currents over the length of the
cable . 13
Figure 3 – Delta A at different frequencies as a function of length . 19
Figure 4 – Delta A for different lengths as a function of frequency . 20
Figure 5 – Delta A for different lengths as a function of frequency (= Delta A + Delta
A ) f = 500 MHz . 21
2 0
Figure 6 – Typical port assignment resulting out of the numbering of the VNA
measuring ports . 21
Figure 7 – Incident and reflected waves, schematically represented for a 2n × 2n
multiport network . 23

Table 1 – Delta A as a function of length or frequency, the other being a parameter . 19

Table 2 – Delta A as a function of frequency (= Delta A + Delta A ) . 20
1 2
TR 61156-1-3  IEC:2011(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTICORE AND SYMMETRICAL PAIR/QUAD
CABLES FOR DIGITAL COMMUNICATIONS –

Part 1-3: Electrical transmission parameters for modelling cable
assemblies using symmetrical pair/quad cables

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC/TR 61156-1-3, which is a technical report, has been prepared by subcommittee 46C:
Wires and symmetric cables, of IEC technical committee 46: Cables, wires, waveguides, R.F.
connectors, R.F. and microwave passive components and accessories.

– 4 – TR 61156-1-3  IEC:2011(E)
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
46C/924/DTR 46C/932/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61156 series, published under the general title Multicore and
symmetrical pair/quad cables for digital communications, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
TR 61156-1-3  IEC:2011(E) – 5 –
MULTICORE AND SYMMETRICAL PAIR/QUAD
CABLES FOR DIGITAL COMMUNICATIONS –

Part 1-3: Electrical transmission parameters for modelling cable
assemblies using symmetrical pair/quad cables

1 Scope
This technical report is a supplement to IEC 61156-1 Edition 3 (2007): Multicore and
symmetrical pair/quad cables for digital communications – Part 1: Generic specification.
This technical report covers the following topics following this standard:
– the near-end crosstalk test methods and length correction procedures of 6.3.5;
– the far-end crosstalk test methods and length correction procedures of 6.3.6;
– the concatenation of measured cable segments, even if they are of different design.
The final objective of this technical report is to describe the mathematics involved to model
the concatenation of cable sections of different length, not based upon measurements but
based upon the specification limits of the cables involved. This is required as a base
foundation of the complete channel modelling, involving also the connectivity covered by IEC
SC48B towards channels, as required and requested by ISO/IEC JTC1/SC25 WG3 for
incorporation into ISO/IEC 11801:2002 [1] .
This TR is informative and contains observations and recommendations applicable to using
the length correction formulas for either measurements or modelling of balanced cables.
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.
IEC 60050-726, International Electrotechnical Vocabulary – Part 726: Transmission lines and
waveguides
IEC 61156-1:2007, Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
IEC/TR 61156-1-2, Multicore and symmetrical pair/quad cables for digital communications –
Part 1-2: Electrical transmission characteristics and test methods of symmetrical pai
...