SIST TBR 024 E1:2004

• Abstract:

  Specification of the attachment requirement for connection of the terminal equipment to the public network and test methods for compliance.

• Status: Published
• Publication Date: 30-Sep-2004
• ICS: 33.040.50 - Lines, connections and circuits
• Technical Committee: BTC - Business telecommunications
• 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-299
• Ref Project: ETSI TBR 024 ed.1 (1997-07) - Business TeleCommunications (BTC); 34 Mbit/s digital unstructured and structured leased lines (D34U and D34S); Attachment requirements for terminal equipment interface

SIST TBR 024 E1:2004 is a Slovenian standard that is identical with TBR 024 Edition 1 from ETSI. It specifies attachment requirements and conformance tests for terminal equipment interfaces used with 34 Mbit/s digital unstructured leased lines (D34U) and 34 Mbit/s digital structured leased lines (D34S). The document is for equipment designers, test laboratories, and buyers who need to check whether terminal equipment can connect to the public network at the Network Termination Point (NTP).

What does SIST TBR 024 E1:2004 specify?

SIST TBR 024 E1:2004 specifies the essential attachment requirements for terminal equipment intended to connect to D34U and D34S leased lines, together with the tests used to check conformance. In practice, it focuses on the terminal equipment interface at the public network boundary, not on the whole end-to-end service.

The scope covers:

• connection to the NTPs of 34 368 kbit/s D34U leased lines
• connection to the NTPs of 34 368 kbit/s D34S leased lines with an information transfer rate of 33 920 kbit/s without restriction on binary content
• mechanical and electrical characteristics of the terminal equipment interface

The document says conformance to these attachment requirements does not by itself guarantee end-to-end interoperability. It also leaves customer premises wiring and installation between the terminal equipment and the NTP outside its scope.

The document is organized into:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Definitions and abbreviations
• Clause 4 - Requirements
• Annexes A to D - normative material
• Annex E - informative bibliography

Annex	What it covers
Annex A	Test methods and test conditions
Annex B	Definition of HDB3 code
Annex C	Definition of frame structure
Annex D	TBR Requirements Table (TBR-RT)
Annex E	Bibliography

What are the key requirements of SIST TBR 024 E1:2004?

SIST TBR 024 E1:2004 sets out the practical interface conditions that terminal equipment must meet before it can be attached to D34U or D34S leased lines. The most important points are mechanical connection, output coding and waveform, timing, jitter, and, for D34S equipment, frame structure.

Mechanical interface

Clause 4.1 requires the terminal equipment interface to provide two coaxial 75 Ω connectors, one for transmit and one for receive. That matters because the equipment must physically mate with the network interface in a consistent way, even though the TBR does not force a specific plug or socket type on the terminal equipment.

Output signal coding

Clause 4.2.1.1 requires the output signal to follow High Density Bipolar code 3 (HDB3). This prevents the network from misreading the signal and helps avoid error reports. Annex B defines how HDB3 handles sequences of zero bits.

Output waveform

Clause 4.2.1.2 requires the output pulse to comply with the pulse mask in figure 2 and the characteristics in table 1, based on ITU-T Recommendation G.703. In practice, this means the signal must have the right shape, level, polarity balance, and pulse width when measured on a 75 Ω non-reactive load.

Output timing

Clause 4.2.1.3 requires the output bit rate to stay within 34 368 kbit/s ± 20 ppm for each timing arrangement the equipment intends to use. The timing may come from an internal source, an external reference, or the received signal at the input port. For a buyer or integrator, this means the supplier needs to declare which timing modes are supported and what reference limits apply.

Output jitter

Clause 4.2.1.4 limits peak-to-peak output jitter and specifies the measurement bandwidths to use. The test also requires the equipment to be exercised with the maximum tolerable input jitter when output timing is derived from another source. In practice, this protects the network from timing instability that can cause errors or slips.

Frame structure for D34S

Clause 4.2.1.5 applies only to equipment intended for D34S. It requires the transmitted bit stream to follow Annex C, including the frame alignment bytes FA1 and FA2 and the frame monitoring functions in the EM and MA bytes. This matters because structured leased lines rely on frame alignment and error monitoring to operate correctly.

Conditional and non-applicable requirements

Annex D marks the frame structure requirement as conditional for D34S use, while the input port, safety, overvoltage protection, and ElectroMagnetic Compatibility (EMC) are not requirements under this TBR. That tells the reader where this document sets essential network-attachment conditions and where other standards or directives apply instead.

What terms does SIST TBR 024 E1:2004 define?

• Frame - A repeating set of bits in which each bit position is identified by a frame alignment signal.
• Frame alignment signal - A distinctive signal placed in every frame at the same position to establish and maintain frame alignment.
• Leased lines - Public network facilities that provide defined transmission characteristics between network termination points without user-controlled switching.
• Network Termination Point (NTP) - The physical connection point and technical access specification that form part of the public telecommunications network.
• Terminal equipment - Equipment intended to connect to the public telecommunications network to send, process, or receive information.
• High Density Bipolar code 3 (HDB3) - A modified Alternate Mark Inversion (AMI) code used to represent bits on the line while controlling long runs of zeros.
• Pseudo Random Bit Sequence (PRBS) - A test bit pattern used to stimulate the interface during conformance testing.

Who uses SIST TBR 024 E1:2004?

SIST TBR 024 E1:2004 is used by manufacturers of terminal equipment, test laboratories, network operators, and conformity assessment teams working with leased-line interfaces. It is especially relevant for people designing, verifying, or approving interfaces for D34U and D34S public network connection.

In practice, these users rely on the document to:

• design the physical interface and signal format
• plan type approval or conformance tests
• check output timing, jitter, and frame structure
• confirm what applies to D34U only and what also applies to D34S
• prepare declarations for implementation or procurement

What changed in SIST TBR 024 E1:2004 from the previous edition?

SIST TBR 024 E1:2004 is identical with TBR 024 Edition 1. The page history shows that this first edition was issued in July 1997.

Which standards are used with SIST TBR 024 E1:2004?

Standard	What it contributes
ITU-T Recommendation G.703	Physical and electrical characteristics of hierarchical digital interfaces, including the basis for the output pulse shape
ITU-T Recommendation O.151	Error performance measuring equipment and PRBS-related test support
ITU-T Recommendation O.171	Timing jitter measuring equipment used for jitter testing
ETS 300 686	Definition of the network interface presentation for D34U and D34S
ETS 300 687	Connection characteristics for D34U and D34S
ETS 300 689	The fuller terminal equipment interface standard from which this TBR is a subset
ETS 300 166	Basis for the terminal equipment interface
EN 60950	Safety reference used in the SELV circuit definition
IEC 169-13	Connector reference mentioned in the connector note

What does the SIST TBR 024 E1:2004 document contain?

SIST TBR 024 E1:2004 contains a requirements section and a set of normative annexes that turn those requirements into testable interface conditions. Annex A gives the test principles, including equipment connection, environmental conditions, and the specific methods for signal coding, waveform shape, output timing, output jitter, and frame structure.

The document also includes the technical definitions for HDB3 in Annex B and the D34S frame structure in Annex C. Annex C describes the frame layout, the alignment bytes FA1 and FA2, and the monitoring bytes used for BIP-8, RDI, and REI checking.

Annex D provides the TBR Requirements Table (TBR-RT), which is useful as a conformance statement proforma. Annex E lists the bibliography, including the directives and companion ETSI and ITU-T documents that support the technical basis of the TBR.

SLOVENSKI STANDARD
01-oktober-2004
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Business TeleCommunications (BTC); 34 Mbit/s digital unstructured and structured
leased lines (D34U and D34S); Attachment requirements for terminal equipment
interface
Ta slovenski standard je istoveten z: TBR 024 Edition 1
ICS:
33.040.50 Vodi, zveze in tokokrogi Lines, connections and
circuits
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL TBR 24
BASIS for July 1997
REGULATION
Source: ETSI TC-BTC Reference: DTBR/BTC-02056
ICS: 33.040.40
Key words: Access, digital, interface, leased line, ONP, terminal, testing, type approval
Business TeleCommunications (BTC);
34 Mbit/s digital unstructured and structured leased lines
(D34U and D34S);
Attachment requirements for terminal equipment interface
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail]
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

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TBR 24: July 1997
Whilst 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.

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TBR 24: July 1997
Contents
Foreword .5
Introduction.5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .7
3.1 Definitions .7
3.2 Abbreviations .8
4 Requirements.9
4.1 Mechanical characteristics.9
4.2 Electrical characteristics .10
4.2.1 Output port .10
4.2.1.1 Signal coding .10
4.2.1.2 Waveform shape .10
4.2.1.3 Output timing .11
4.2.1.4 Output jitter .11
4.2.1.5 Output frame structure.12
4.2.2 Input port .12
4.3 Safety.13
4.4 Overvoltage protection.13
4.5 ElectroMagnetic Compatibility (EMC) .13
Annex A (normative): Test methods.14
A.1 General.14
A.1.1 Equipment connection .14
A.1.2 Test environment .14
A.2 Test methods .15
A.2.1 Signal coding at the output port .15
A.2.2 Waveform shape at the output port .15
A.2.3 Output timing.16
A.2.4 Output jitter .17
A.2.5 Frame structure .18
Annex B (normative): Definition of HDB3 code .19
B.1 General.19
B.2 Definition .19
Annex C (normative): Definition of frame structure .20
C.1 Frame structure at 34 368 kbit/s .20
Annex D (normative): TBR Requirements Table (TBR-RT).21
Annex E (informative): Bibliography.22
History.23

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TBR 24: July 1997
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TBR 24: July 1997
Foreword
This Technical Basis for Regulation (TBR) has been produced by the Business TeleCommunications
(BTC) Technical Committee, in conjunction with the Terminal Equipment (TE) and Transmission and
Multiplexing (TM) Technical Committees, of the European Telecommunications Standards Institute
(ETSI).
This TBR resulted from a mandate from the Commission of the European Community (CEC) to provide
harmonized standards for the support of the Second Phase Directive (91/263/EEC).
This TBR is based on information from ITU-T Recommendations and ETSI publications and the relevant
documents are quoted where appropriate.
Introduction
The Council Directive on the application of Open Network Provision (ONP) to leased lines (92/44/EEC)
concerns the harmonization of conditions for open and efficient access to, and use of, the leased lines
provided over public telecommunications networks, and the availability throughout the European Union of
a minimum set of leased lines with harmonized technical characteristics.
At the date of publication of this TBR, the 34 Mbit/s unstructured and structured leased lines are not part
of the minimum set of leased lines under the Leased Line Directive and it is not planned that they will be
added to the minimum set.
Two classes of standard will be used for the interfaces of terminal equipment designed for connection to
the ONP leased lines. European Telecommunications Standards (ETSs), which are voluntary, give the full
technical specifications for these interfaces, whereas TBRs give the essential requirements under the
Second Phase Directive (91/263/EEC) for attachment to the leased lines. This TBR is a subset of the
corresponding ETS 300 689.
ETS 300 166 and ITU-T Recommendation G.703 are used as the basis for the terminal equipment
interface.
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TBR 24: July 1997
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TBR 24: July 1997
1 Scope
This TBR specifies the attachment requirements and the corresponding conformance tests for a terminal
equipment interface for:
- connection to the Network Termination Points (NTPs) of 34 368 kbit/s digital unstructured leased
lines (D34U); and
- connection to the NTPs of 34 368 kbit/s digital structured leased lines (D34S) with an information
transfer rate of 33 920 kbit/s without restriction on binary content.
These leased lines are defined in ETS 300 686 and ETS 300 687.
The term "attachment requirements" in the context of this TBR refers to the essential requirements for
access that apply under articles 4d and 4f of the Second Phase Directive (91/263/EEC). Conformance to
these requirements does not guarantee end-to-end interoperability. Essential requirements under articles
4c and 4e are not applicable to this TBR.
This TBR is applicable to all interfaces intended for connection to the D34U or D34S leased line. It covers
the essential requirements for the mechanical and electrical characteristics of the terminal equipment
interface. Interfaces intended only for connection to the D34U leased lines which do not comply with the
specified requirements on output structure, do not satisfy the attachment requirements for connection to
the D34S leased line.
Customer premises wiring and installation between the terminal equipment and the NTP are outside the
scope of this TBR.
2 Normative references
This TBR incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to, or revisions of any of these publications
apply to this TBR only when incorporated into it by amendment or revision. For undated references the
latest edition of the publication referred to applies.
[1] ITU-T Recommendation G.703 (1991): "Physical/electrical characteristics of
hierarchical digital interfaces".
[2] ITU-T Recommendation O.151 (1992): "Error performance measuring
equipment for digital systems at the primary rate and above".
[3] ITU-T Recommendation O.171 (1992): "Timing jitter measuring equipment for
digital systems".
NOTE: This TBR also contains a number of informative references which have been included
to indicate the sources from which various material has been derived, hence they do
not have an associated normative reference number. Details of these publications are
given in annex E. In some cases the same publication may have been referenced in
both a normative and an informative manner.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this TBR, the following definitions apply:
frame: A repetitive set of consecutive bits in which the position of each bit can be identified by reference
to a frame alignment signal.
frame alignment signal: The distinctive signal inserted in every frame always occupying the same
relative position within the frame and used to establish and maintain frame alignment.

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TBR 24: July 1997
leased lines: The telecommunications facilities provided by a public telecommunications network that
provide defined transmission characteristics between network termination points, and that do not include
switching functions that the user can control (e.g. on-demand switching).
Network Termination Point (NTP): All physical connections and their technical access specifications
which form part of the public telecommunications network and are necessary for access to and efficient
communication through that public network.
23-1
PRBS(2 ): A Pseudo Random Bit Sequence (PRBS) (as defined in subclause 2.2 of ITU-T
Recommendation O.151 [2]).
Safety Extra-Low Voltage (SELV) circuit: A secondary circuit which is so designed and protected that
under normal and single fault conditions, the voltage between any two accessible parts and, for class 1
equipment, between any accessible part and the equipment protective earthing terminal does not exceed
a safe value (subclause 1.2.8.5 of EN 60950).
terminal equipment: Equipment intended to be connected to the public telecommunications network, i.e.:
- to be connected directly to the termination of a public telecommunication network; or
- to interwork with a public telecommunications network being connected directly or indirectly to the
termination of a public telecommunications network,
in order to send, process, or receive information.
3.2 Abbreviations
For the purposes of this TBR, the following abbreviations apply:
ac alternating current
AMI Alternate Mark Inversion
BNC Bayonet Nut Connector
D34S 34 Mbit/s digital structured leased line
D34U 34 Mbit/s digital unstructured leased line
dc direct current
EMC ElectroMagnetic Compatibility
FA1 Frame Alignment byte 1
FA2 Frame Alignment byte 2
HDB3 High Density Bipolar code 3
LSB Least Significant Bit
MSB Most Significant Bit
NTP Network Termination Point
ONP Open Network Provision
ppm parts per million
PRBS Pseudo Random Bit Sequence
RDI Remote Defect Indication
REI Remote Error Indication
RX RX is a signal input (at either the terminal equipment or the test equipment,
see figure 1)
SELV Safety Extra-Low Voltage
TBR-RT TBR-Requirements Table
TX TX is a signal output (at either the terminal equipment or the test equipment,
see figure 1)
UI Unit Interval
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TBR 24: July 1997
4 Requirements
The terminal equipment is for use with D34U or D34S leased lines.
The D34U 34 368 kbit/s unstructured leased line provides a bi-directional point-to-point digital connection
with an information transfer rate of 34 368 kbit/s without restriction on binary content. Any structuring of
the data is the responsibility of the user.
The D34S 34 368 kbit/s structured leased line provides a bi-directional point-to-point digital connection
with an information transfer rate of 33 920 kbit/s without restriction on binary content. Any structuring of
the data within the transparent 33 920 kbit/s part of the frame is the responsibility of the user.
For both D34U and D34S the provision of timing is the responsibility of the user; however, in certain
installations the leased line provider may be able to offer a leased line that is synchronized to the network.
4.1 Mechanical characteristics
Justification: Without a means of connection, it is impossible for the terminal equipment to connect to the
network, therefore this is included in order for the terminal equipment to interwork with the network
(article 4f).
Requirement: The terminal equipment interface shall provide two coaxial 75 Ω connectors, one each for
transmit and receive.
There is no requirement under this TBR for a particular plug or socket to be provided on the terminal
equipment.
NOTE 1: ETS 300 689 specifies that the terminal equipment shall provide either:
- two coaxial sockets, one each for transmit and receive; these sockets being
either 75 Ω sockets complying with IEC 169-13 or 75 Ω Bayonet Nut Connector
(BNC) sockets; or
- two coaxial plugs at the end of a cord (or cords), one each for transmit and
receive; these plugs being either 75 Ω plugs complying with IEC 169-13 or 75 Ω
BNC plugs.
NOTE 2: The transmit pair is the output from the terminal equipment interface. The receive pair
is the input to the terminal equipment interface, as shown in figure 1. Where the terms
"output" and "input" are used without qualification in this TBR, they refer to the terminal
equipment interface.
NOTE 3: Normal practice is for the outer conductors of the input and output connectors to be
connected via a dc path to the signal ground and thence to ground. This connection is
to reduce EMC emissions. If there is a difference in ground potential between the
terminal equipment and the NTP, this arrangement may result in high currents in the
outer conductors and cause damage.
To prevent this problem, dc isolation may be introduced between the terminal
equipment and the NTP, for example by introducing dc isolation between the outer
conductor and the signal ground in the terminal equipment. Careful attention should be
given to the requirements of standards on installation earthing practice.
OUTPUT INPUT
TX RX
TERMINAL
NETWORK
EQUIPMENT
INTERFACE
INTERFACE
RX TX
INPUT OUTPUT
Figure 1
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TBR 24: July 1997
Test: There shall be a visual inspection that two 75 Ω connectors are provided.
4.2 Electrical characteristics
4.2.1 Output port
4.2.1.1 Signal coding
Justification: The correct signal coding is necessary for the output signals from the terminal equipment to
be recognized correctly at the input to the NTP. Failure to provide the correct coding may cause error
reports within the network. A requirement on signal coding is therefore included in order to prevent harm
to the network (article 4d).
Requirement: The signal transmitted at the output port shall comply with the High Density Bipolar code 3
(HDB3) encoding rules (see annex B).
Test: The test shall be conducted according to subclause A.2.1.
4.2.1.2 Waveform shape
Justification: The correct waveform shape both limits the voltages to line and ensures correct recognition
of the pulses. Incorrect recognition of pulses may cause error reports within the network. A requirement on
waveform shape is therefore included in order to prevent harm to the network (article 4d).
Requirement: The pulse at the output port shall comply with the requirements given in figure 2 and
table 1; based on ITU-T Recommendation G.703.
17 ns
(14,55 + 2,45)
V
0,2
0,1
1,0
8,65 ns
0,1
(14,55 - 5,90)
0,2
Nominal
pulse
14,55 ns
0,5
12,1 ns
(14,55 - 2,45)
24,5
0,1 0,1
(14,55 + 9,95)
0,1 0,1
0,2
29,1 ns
(14,55 + 14,55)
Figure 2: Pulse mask for 34 Mbit/s pulse

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TBR 24: July 1997
Table 1: Waveform shape at output port
Pulse shape (nominally rectangular) All marks of a valid signal shall conform with the
mask (see figure 2). The value V corresponds to the
nominal peak voltage of a mark.
Test load impedance
75 Ω non-reactive
Nominal peak voltage V of a mark 1,0 V
Peak voltage of a space 0 ± 0,1 V
Nominal pulse width 14,55 ns
Ratio of the amplitudes of positive and negative 0,95 to 1,05
pulses at the centre of the pulse interval
Ratio of the widths of positive and negative pulses 0,95 to 1,05
at the nominal half amplitude
Test: The test shall be conducted according to subclause A.2.2.
4.2.1.3 Output timing
Justification: Pulses at the wrong bit rate may not be properly recognized and may cause error reports
within the network. A requirement on output timing is therefore included in order to prevent harm to the
network (article 4d).
The terminal equipment may derive its timing from:
a) an internal source (e.g. an internal clock);
b) an external reference signal input;
c) the received signal at the input port.
Requirement: For each of the timing arrangements intended for use, the bit rate at the output port shall
be within the limits of 34 368 kbit/s ± 20 parts per million (ppm), when any relevant external reference
signal, including the received signal at the input port, is within its stated tolerance.
Test: The test shall be conducted according to subclause A.2.3.
4.2.1.4 Output jitter
Justification: A high level of jitter causes error reports within some networks, therefore this requirement
is included to prevent harm to the network (article 4d).
Requirement: The peak-to-peak output jitter shall not exceed the limits of table 2 when measured with a
band pass filter with the defined cut-off frequencies. At frequencies below the lower 3 dB point, the
attenuation of the high pass filter shall rise with a value greater than, or equal to, 20 dB per decade. At
frequencies above the upper 3 dB point, the attenuation of the low pass filtration shall rise with a value
greater than, or equal to, 60 dB per decade.
For the purpose of testing, any signal input from
...