SIST ETS 300 420 E1:2004
(Main)Business TeleCommunications (BTC); 2 048 kbit/s digital structured leased lines (D2048S); Terminal equipment interface
Business TeleCommunications (BTC); 2 048 kbit/s digital structured leased lines (D2048S); Terminal equipment interface
Specification of the terminal equipment side of the interface and test procedures for compliance.
Poslovne telekomunikacije (BTC) - Digitalni zakupljeni vodi za prenosno hitrost 2 048 kbit/s in za strukturirane signale (D2048S) - Vmesnik terminalske opreme
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2004
Poslovne telekomunikacije (BTC) - Digitalni zakupljeni vodi za prenosno hitrost 2
048 kbit/s in za strukturirane signale (D2048S) - Vmesnik terminalske opreme
Business TeleCommunications (BTC); 2 048 kbit/s digital structured leased lines
(D2048S); Terminal equipment interface
Ta slovenski standard je istoveten z: ETS 300 420 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.
EUROPEAN ETS 300 420
TELECOMMUNICATION November 1995
STANDARD
Source: ETSI TC-BTC Reference: DE/BTC-02023
ICS: 33.040.40
ONP, leased line, D2048S, terminal equipment
Key words:
Business TeleCommunications (BTC);
2 048 kbit/s digital structured leased lines (D2048S);
Terminal equipment interface
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
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 1995. All rights reserved.
New presentation - see History box
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ETS 300 420: November 1995
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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ETS 300 420: November 1995
Contents
Foreword .5
Introduction.5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions .8
3.2 Abbreviations .8
4 Requirements.9
4.1 Physical characteristics.9
4.1.1 Hardwired connection.10
4.1.2 Alternative means of connection .10
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 Impedance towards ground .12
4.2.1.5 Output jitter .12
4.2.1.6 Output return loss .13
4.2.1.7 Output signal balance.13
4.2.1.8 Output structure.13
4.2.1.8.1 CRC-4.13
4.2.1.8.2 Use of the E-bits .13
4.2.1.8.3 Use of the A-bit .13
4.2.1.8.4 Use of the S bits .14
a
4.2.2 Input port .14
4.2.2.1 Signal coding .14
4.2.2.2 Input return loss.14
4.2.2.3 Input loss tolerance.15
4.2.2.4 Immunity against reflections .15
4.2.2.5 Tolerable longitudinal voltages .15
4.2.2.6 Impedance towards ground .15
4.2.2.7 Input jitter tolerance .15
4.2.2.8 Input clock tolerance.16
4.2.2.9 Input frame structure .16
4.2.2.9.1 Frame alignment.16
4.2.2.9.2 Multiframe alignment .17
4.3 Safety.17
4.3.1 General requirements.17
4.3.2 Touch current .17
4.4 Overvoltage protection.18
4.4.1 Surge simulation, common mode.18
4.4.2 Surge simulation, transverse mode between transmit and receive pairs.18
4.4.3 Mains simulation, common mode.18
4.4.4 Mains simulation, transverse mode.18
4.4.5 Impulse transfer from mains, common mode .18
4.4.6 Impulse transfer from mains, transverse mode .19
4.4.7 Conversion of common mode to transverse mode .19
4.4.8 Impulse transfer from auxiliary interface .19
4.5 ElectroMagnetic Compatibility (EMC) .19
Annex A (normative): Test methods.20
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ETS 300 420: November 1995
A.1 General. 20
A.1.1 Additional information to support the test. 20
A.1.2 Equipment connection. 20
A.2 Test methods. 21
A.2.1 Signal coding at the output port. 21
A.2.2 Waveform shape at output port. 22
A.2.3 Output timing. 23
A.2.4 Return loss at input port . 24
A.2.5 Input loss tolerance and immunity against reflections. 24
A.2.6 Tolerable longitudinal voltage, HDB3 input coding. 26
A.2.7 Impedance towards ground. 27
A.2.8 Input and output jitter. 27
A.2.9 Frame structure. 29
A.2.9.1 Output structure and CRC-4 generation. 29
A.2.9.2 Terminals not using the E-bits . 30
A.2.9.3 Terminals using the E-bits to indicate errored SMFs. 30
A.2.9.4 Use of the A-bit. 31
A.2.10 Input frame structure. 33
A.2.10.1 Frame alignment. 33
A.2.10.2 Multiframe alignment . 35
Annex B (normative): Definition of HDB3 code. 36
B.1 General. 36
B.2 Definition. 36
Annex C (normative): Definition of frame structure. 37
C.1 Frame structure . 37
C.2 CRC-4. 37
C.2.1 CRC-4 generation . 38
C.2.2 CRC-4 monitoring . 38
Annex D (normative): ETS Requirements Table (ETS-RT). 39
Annex E (informative): Timing synchronization . 41
E.1 General. 41
E.1.1 User timing . 41
E.1.2 Network timing . 41
E.2 Further information . 41
Annex F (informative): Bibliography . 42
History. 43
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ETS 300 420: November 1995
Foreword
This European Telecommunication Standard (ETS) has been produced by the Business
TeleCommunications (BTC) Technical Committee of the European Telecommunications Standards
Institute (ETSI).
This ETS results from a mandate from the Commission of the European Community (CEC) to provide
harmonized standards for the support of the Directive on Open Network Provision (ONP) of leased lines
(92/44/EEC).
There are two other standards directly related to this ETS:
- ETS 300 418: "Business TeleCommunications (BTC); 2 048 kbit/s digital unstructured and
structured leased lines (D2048U and D2048S); Network interface presentation";
- ETS 300 419: "Business TeleCommunications (BTC); 2 048 kbit/s digital structured leased line
(D2048S); Connection characteristics".
This ETS is based on information from ITU-T Recommendations and ETSI publications and the relevant
documents are quoted where appropriate.
Transposition dates
Date of adoption of this ETS 17 November 1995
Date of latest announcement of this ETS (doa): 28 February 1996
Date of latest publication of new National Standard 31 August 1996
or endorsement of this ETS (dop/e):
Date of withdrawal of any conflicting National Standard (dow): 31 August 1996
Introduction
The Council Directive on the application of 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 (EU) of a minimum set
of leased lines with harmonized technical characteristics.
The consequence of the Directive is that telecommunications organizations within the EU shall make
available a set of leased lines between points in these countries with specified connection characteristics
and specified interfaces.
Two classes of standard will be used for the interfaces of terminal equipment designed for connection to
the ONP leased lines. European Telecommunication Standards (ETSs), which are voluntary, give the full
technical specifications for these interfaces, whereas Technical Basis for Regulations (TBRs) give the
essential requirements under the Second Phase Directive (91/263/EEC) for attachment to the leased
lines. This standard, which is an ETS, belongs to the first category. The TBR (TBR 13) is a subset of this
corresponding ETS.
ETS 300 166 and CCITT Recommendations G.703, G.704 and G.706 are used as the basis for the
terminal interface.
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ETS 300 420: November 1995
1 Scope
This ETS specifies the full physical and electrical characteristics, the necessary functional characteristics
and the corresponding test principles for a terminal equipment interface for connection to the Network
Termination Points (NTPs) of Open Network Provision (ONP) 2 048 kbit/s digital structured leased lines
using 120 Ω interfaces with an information transfer rate of 1 984 kbit/s without restriction on binary
content.
This ETS is not intended for regulatory purposes. A separate TBR (TBR 13) covers the essential
requirements for attachment under the Second Phase Directive (91/263/EEC).
This ETS is to ensure that the interface of the terminal equipment is compatible with the ONP 2 048 kbit/s
digital structured leased line. A terminal equipment interface that conforms to this ETS will also be
compatible with an ONP 2 048 kbit/s unstructured leased line. This ETS is applicable to all interfaces
designed for connection to the leased line, however in the cases of apparatus that carries a particular
service, of complex apparatus and of apparatus in private networks, other ETSs may apply in addition to
this ETS.
Customer premises wiring and installation between the terminal equipment and the NTP are outside the
scope of this ETS.
2 Normative references
This ETS incorporates by dated and 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 ETS only when incorporated into it by amendment or revision. For undated references the
latest edition of the publication referred to applies.
[1] CCITT Recommendation G.703 (1991): "Physical/electrical characteristics of
hierarchical digital interfaces".
[2] CCITT Recommendation G.704 (1991): "Synchronous frame structures used at
primary and secondary hierarchical levels".
[3] CCITT Recommendation O.151 (1992): "Error performance measuring
equipment for digital systems at the primary rate and above".
[4] CCITT Recommendation O.171 (1992): "Timing jitter measuring equipment for
digital systems".
[5] EN 60950 (1992): "Safety of information technology equipment including
electrical business equipment".
[6] ETS 300 046-2 (1992): "Integrated Services Digital Network (ISDN); Primary
rate access - safety and protection Part 2: Interface I - safety".
a
[7] ETS 300 046-3 (1992): "Integrated Services Digital Network (ISDN); Primary
rate access - safety and protection Part 3: Interface I - protection".
a
NOTE: This ETS 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 F. In some cases the same publication may have been referenced in
both a normative and an informative manner.
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ETS 300 420: November 1995
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
errored Sub-MultiFrame: A Sub-MultiFrame (SMF) where the calculated Cyclic Redundancy Check-4 bit
(CRC-4) does not correspond with the CRC-4 contained within the next SMF (see subclause C.2.2).
frame: A sequence of 256 bits of which the first 8 bits define the frame structure (see annex C).
leased lines: The telecommunications facilities provided by a public telecommunications network that
provide defined transmission characteristics between NTPs and that do not include switching functions
that the user can control, (e.g. on-demand switching).
multiframe: A sequence of two SMFs containing the multiframe alignment word (see annex C).
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.
PRBS(2 -1): A Pseudo Random Bit Sequence (PRBS) (as defined in subclause 2.1 of CCITT
Recommendation O.151 [3]).
S bits: bits 4 to 8 (bits S to S ) in frames not containing the frame alignment signal (see annex C).
a4 a8
a
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 [5]).
Sub-Multiframe (SMF): A sequence of 8 frames, each of 256 bits, over which the CRC-4 is calculated
(see annex C).
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 ETS, the following abbreviations apply:
AIS Alarm Indication Signal
AMI Alternate Mark Inversion
CRC-4 Cyclic Redundancy Check-4 bit
D2048S 2 048 kbit/s digital structured leased line
dc direct current
EMC ElectroMagnetic Compatibility
ETS-RT ETS Requirements Table
HDB3 High Density Bipolar code of order 3 (see annex B)
ISDN Integrated Services Digital Network
NTP Network Termination Point
ONP Open Network Provision
ppm parts per million
PRBS Pseudo Random Bit Sequence
RAI Remote Alarm Indication
rms root mean square
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ETS 300 420: November 1995
RX RX is a signal input (at either the terminal equipment interface or the test
equipment, see figure 1)
SDH Synchronous Digital Hierarchy
SELV Safety Extra-Low Voltage
SMF Sub-MultiFrame
TX TX is a signal output (at either the terminal equipment interface or the test
equipment, see figure 1)
UI Unit Interval
4 Requirements
The terminal equipment interface is for use with 2 048 kbit/s structured leased lines that provide
bidirectional, point-to-point digital connections with an information transfer rate of 1 984 kbit/s without
restriction on binary content. Any structuring of the data within the transparent 1 984 kbit/s part of the
frame is the responsibility of the user.
4.1 Physical characteristics
Currently no standardised connector is readily available. Consequently, the only method of connection that
can be specified in this ETS is the use of solid conductors of 0,4 mm to 0,6 mm. This ETS requires the
terminal equipment to be capable of presenting either a point for the attachment of unterminated solid
conductors, or solid conductors themselves (see subclause 4.1.1). It is a requirement that such a
connection method be available to be provided for use with the terminal equipment if necessary.
In order to allow connection to be made using other methods (e.g. connectors), the terminal equipment is
permitted to be supplied with a connection method suitable for use with those methods (see
subclause 4.1.2).
NOTE: The following are examples of arrangements that comply with the requirements. The
list below should not be regarded as an exhaustive list of all permitted arrangements:
a) a cord, permanently connected to the terminal equipment at one end and
unterminated at the other end, with wires that are solid conductors with
diameters in the range 0,4 mm to 0,6 mm;
b) a cord, connected via a plug and socket to the terminal equipment at one end
and unterminated at the other end, with wires that are solid conductors with
diameters in the range 0,4 mm to 0,6 mm;
c) an insulation displacement connector, designed to accept wires with solid
conductors with diameters in the range 0,4 mm to 0,6 mm, but with no cord;
d) a screw connector, designed to accept wires with solid conductors with
diameters in the range 0,4 mm to 0,6 mm, but with no cord;
e) the arrangement in b) plus one or more additional alternative cords with the
same plug or socket arrangement at the terminal end and any plug or socket at
the other end;
f) the arrangement in c) or d) plus one or more cords suitable for connection to the
terminal equipment at one end and any plug or socket at the other end.
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 ETS, they refer to the terminal equipment interface.
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ETS 300 420: November 1995
Input
Output
RX
TX
Network Terminal
Interface Equipment
RX TX
Input
Output
Figure 1
NOTE: The use of a shielded cord or cable may be necessary to meet radiation and immunity
requirements defined in ElectroMagnetic Compatibility (EMC) standards.
4.1.1 Hardwired connection
Requirement: The terminal equipment shall provide:
a) a set of connection contacts (e.g. an insulation displacement connector or a screw terminal block)
to which solid wire conductors with diameters in the range 0,4 mm to 0,6 mm may be connected; or
b) a wiring arrangement connected by any means to the terminal equipment, with unterminated solid
wire conductors with diameters in the range 0,4 mm to 0,6 mm at the end distant from the terminal
equipment.
Test: There is no test. All subsequent tests are carried out via the specified connection method.
4.1.2 Alternative means of connection
Any alternative means of connection may be provided in addition to the connection arrangements under
subclause 4.1.1.
4.2 Electrical characteristics
4.2.1 Output port
4.2.1.1 Signal coding
Requirement: The signal transmitted at the output port shall comply with the High Density Bipolar code of
order 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
Requirement: The pulse at the output port shall comply with the requirements given in table 1 and
figure 2, based on CCITT Recommendation G.703 [1].
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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) irrespective of the
polarity. The value V corresponds to the
nominal peak voltage of a mark.
Test load impedance 120 Ω non-reactive
Nominal peak voltage V of a mark 3 V
Peak voltage of a space 0 ± 0,3 V
Nominal pulse width 244 ns
Ratio of the amplitudes of positive and negative pulses at 0,95 to 1,05
the centre of the pulse interval
Ratio of the widths of positive and negative pulses at the 0,95 to 1,05
nominal half amplitude
269 ns
(244 + 25)
20%
10%
V=100%
194 ns
10%
(244 - 50)
20%
Nominal pulse
50%
244 ns
219 ns
10% 10%
(244 - 25)
0%
10% 10%
20%
488 ns
(244 + 244)
Figure 2: Pulse mask for 2 048 kbit/s pulse
Test: The test shall be conducted according to subclause A.2.2.
4.2.1.3 Output timing
This requirement is such that the terminal equipment is capable of operating when connected to leased
lines capable of carrying user timing within the range 2 048 kbit/s ± 50 parts per million (ppm) and when
connected to leased lines that provide timing that is synchronous to the network timing. For further
information see annex E.
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ETS 300 420: November 1995
Requirement: The terminal equipment shall have:
a) an internal clock which shall provide a bit rate at the output port within the limits of
2 048 kbit/s ± 50 ppm; and
b) the capability to provide a clock loop such that the signal timing at the output port is derived from
the timing at the input port.
The terminal equipment may also have:
c) an external reference signal input from which the output timing may be derived.
Test: For case a) the test shall be conducted according to subclause A.2.3. The capability to provide a
clock loop, case b), and the derivation of a clock signal from an external reference signal input, case c),
are covered by the test of subclause A.2.8.
4.2.1.4 Impedance towards ground
Requirement: Where the terminal equipment has a ground, the impedance towards ground of the output
port shall be greater than 1 000 Ω for frequencies in the range 10 Hz to 1 MHz when measured with a
sinusoidal test voltage of 2 V root mean square (rms). For the purpose of this requirement, ground shall
be the terminal equipment common reference point or test reference point.
NOTE: This requirement is included to allow transformerless implementations.
Test: The test shall be conducted according to subclause A.2.7.
4.2.1.5 Output jitter
Requirement: The peak-to-peak output jitter shall not exceed the limits of table 2 when measured with a
band pass filter with linear cut-off 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 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 which the output timing is derived shall be provided with
the maximum tolerable input jitter, and with the maximum tolerable input frequency deviation, as specified
by the manufacturer.
Where the output timing of the terminal equipment is taken from the leased line, the input to the terminal
equipment shall be provided with components of sinusoidal jitter at points on the curve of figure 3 and
table 4.
NOTE: A separate requirement for output jitter at frequencies below 40 Hz is not required
because the measurement filter with a first order lower cut-off will allow the jitter to
have a spectrum whose amplitude rises at 20 dB/decade as the frequency reduces
below 40 Hz. Where timing is taken from the leased line, the test uses input jitter
frequencies from 20 Hz upwards.
Table 2: Maximum output jitter
Measurement filter bandwidth Output jitter
Lower cut-off Upper cut-off Unit Interval (UI) peak-to-peak
(high pass) (low pass) (maximum)
40 Hz 100 kHz 0,11 UI
Test: The test shall be conducted according to subclause A.2.8.
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ETS 300 420: November 1995
4.2.1.6 Output return loss
There are no requirements for output return loss under this ETS.
NOTE: A requirement for output return loss may be added to this ETS when appropriate
specifications become available.
4.2.1.7 Output signal balance
There are no requirements for output signal balance under this ETS.
NOTE: The effects of the output signal imbalance are covered under the EMC Directive
(89/336/EEC).
4.2.1.8 Output structure
Requirement: The bit stream transmitted at the output of the terminal equipment shall be structured as
defined in clause C.1.
Test: The test shall be conducted according to subclause A.2.9.1.
4.2.1.8.1 CRC-4
Requirement: The CRC-4 bits transmitted at the output of the terminal equipment shall be as defined in
tables C.1 and C.2 and subclause C.2.1 of annex C and shall correspond to the data transmitted at the
output of the terminal equipment.
Test: The test shall be conducted according to subclause A.2.9.1.
4.2.1.8.2 Use of the E-bits
The terminal equipment shall comply either with subclause 4.2.1.8.2.1 or subclause 4.2.1.8.2.2.
4.2.1.8.2.1 Terminals not using the E-bits
This subclause is applicable to those terminal equipments which do not use the E-bits to indicate errored
SMFs.
Requirement: Both E-bits transmitted at the output of the terminal equipment shall be set to binary ONE
in all instances.
Test: The test shall be conducted according to subclause A.2.9.2.
4.2.1.8.2.2 Terminals using the E-bits to indicate errored SMFs
This subclause is applicable to those terminal equipments which use the E-bits to indicate errored SMFs.
Requirement: The E-bits transmitted at the output of the terminal equipment shall indicate errored SMFs
in the input bit stream. One E-bit in a multiframe shall be set to binary ZERO for each errored SMF
received in the input bit stream. The E-bits corresponding to non-errored SMFs shall be set to binary ONE.
Any delay between the detection of an errored SMF and the setting of the E-bit that indicates the errored
SMF shall be less than 1 second.
Test: The test shall be conducted according to subclause A.2.9.3.
4.2.1.8.3 Use of the A-bit
The terminal equipment shall comply either with subclause 4.2.1.8.3.1 or subclause 4.2.1.8.3.2.
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ETS 300 420: November 1995
4.2.1.8.3.1 Terminals not using the A-bit
Requirement: The A-bit transmitted at the output of the terminal equipment shall be set to binary ZERO in
all instances.
Test: The test shall be conducted according to subclause A.2.9.4.
4.2.1.8.3.2 Terminals using the A-bit
Requirement: The A-bit transmitted at the output of the terminal equipment shall be set to binary ZERO in
normal operation but may be changed from binary ZERO to binary ONE within 30 ms of any of the
following conditions occurring in the input bit stream:
a) three consecutive incorrect frame alignment signals, (the correct frame alignment signal is defined
in table C.1);
b) there being = 915 errored SMFs out of 1 000 SMFs.
The terminal may also change the A-bit from binary ZERO to binary ONE within 30 ms of:
c) bit 2 in frames not containing the frame alignment signal being in error (i.e. bit 2 is a binary ZERO)
on three consecutive occasions.
For a terminal equipment recovering from loss of frame alignment (i.e. the A-bit set to binary ONE) the
A-bit transmitted at the output of the terminal equipment shall be set from binary ONE to binary ZERO
within 30 ms of any of the following conditions occurring in the input bit stream:
d) for the first time, the presence of the correct frame alignment signal (as defined in table C.1); and
e) the absence of the frame alignment signal in the following frame detected by verifying that bit 2 of
the basic frame is a binary ONE; and
f) for the second time, the presence of the correct frame alignment signal in the next frame.
Test: The test shall be conducted according to subclause A.2.9.4.
4.2.1.8.4 Use of the S bits
a
There is no requirement on the value or setting of the S bits at the output of the terminal equipment.
a
4.2.2 Input port
4.2.2.1 Signal coding
Requirement: The input port shall decode without error HDB3 encoded signals in accordance with HDB3
encoding rules (see annex B).
Test: The test shall be conducted according to subclause A.2.6.
4.2.2.2 Input return loss
Requirement: The input return loss with respect to 120 Ω at the interface shall be greater than or equal to
the values given in table 3, which is taken from subclause 6.3.3 of CCITT Recommendation G.703 [1].
Table 3: Input port minimum return loss
Frequency range Return loss
51 kHz to 102 kHz 12 dB
102 kHz to 2 048 kHz 18 dB
2 048 kHz to 3 072 kHz 14 dB
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ETS 300 420: November 1995
Test: The test shall be conducted according to subclause A.2.4.
4.2.2.3 Input loss tolerance
Requirement: The input port shall decode without errors a 2 048 kbit/s signal as defined in
subclauses 4.2.1.1 and 4.2.1.2 above but modified by a cable or artificial cable with the following
characteristics:
a) attenuation that follows a ¹f law with values throughout the range 0 to 6 dB at 1 024 kHz; and
b) characteristic impedance of 120 Ω with a tolerance of ± 20 % in the frequency range from 200 kHz
up to, but not including, 1 MHz, and ± 10 % at 1 MHz.
Test: The test shall be according to subclause A.2.5.
4.2.2.4 Immunity against reflections
Requirement: When a signal comprising a combination of a normal signal and an interfering signal is
applied to the input port, via an artificial cable with a loss in the range 0 dB to 6 dB at 1 MHz, no errors
shall result due to the interfering signal.
The normal signal shall be a signal encoded according to HDB3, shaped according to the mask of
figure 2, with a binary content in accordance with a PRBS(2 -1).
The interfering signal shall be the same as the normal signal except that the level is attenuated by 18 dB,
the bit rate is within 2 048 kbit/s ± 50 ppm and the timing shall not be synchronized to the normal signal.
Test: The test shall be conducted according to subclause A.2.5.
4.2.2.5 Tolerable longitudinal voltages
Requirement: The receiver shall operate without errors with any input signal in the presence of a
longitudinal voltage of magnitude 2 V rms over the frequency range 10 Hz to 30 MHz.
NOTE: This requirement is included to allow transformerless implementations.
Test: The test shall be conducted according to subclause A.2.6.
4.2.2.6 Impedance towards ground
Requirement: Where the terminal equipment has a ground, the impedance towards ground of the input
port shall be greater than 1 000 Ω for frequencies in the range 10 Hz to 1 MHz when measured with a
sinusoidal test voltage of 2 V rms. For the purpose of this requirement, ground shall be the terminal
equipment common reference point or test reference point.
NOTE: This requirement is included to allow transformerless implementations.
Test: The test shall be conducted according to subclause A.2.7.
4.2.2.7 Input jitter tolerance
Requirement: The terminal equipment shall tolerate at its input port the maximum input jitter as shown in
table 4 and figure 3.
NOTE: Terminal equipment with more than one input will normally need to be designed with a
wander buffer of at least 18 μs, however, to accommodate the wander that may be
produced by Synchronous Digital Hierarchy (SDH) networks, up to 40 μs may be
needed.
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ETS 300 420: November 1995
Table 4: Input jitter tolerance
Peak-to-peak amplitude (UI) Frequency (Hz)
A1 A2 f1 f2 f3 f4
1,5 0,2 20 2 400 18 000 100 000
peak-to-peak jitterpeak-to-peak jitter
A1A1
A2A2
f1f1 f2f2 f3f3 f4f4
jitter frequencyjitter frequency
Figure 3: Input jitter tolerance
Test: The test shall be conducted according to subclause A.2.8.
4.2.2.8 Input clock tolerance
Requirement: The terminal equipment shall decode without error HDB3 encoded signals over the
frequency range 2 048 kbit/s ± 50 ppm.
Test: The test shall be conducted in accordance with subclause A.2.8.
4.2.2.9 Input frame structure
4.2.2.9.1 Frame alignment
Requirement: The input port shall accept an input bit stream with a frame and multiframe structure as
defined in annex C. The terminal equipment shall be capable of achieving frame alignment in order to
separate the user data from the frame information.
Frame alignment shall be achieved following:
a) for the first time, the presence of the correct frame alignment signal; and
b) the absence of the frame alignment signal in the following frame detected by verifying that bit 2 of
the basic frame is a binary ONE; and
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ETS 300 420: November 1995
c) for the second time, the presence of the correct frame alignment signal in the next frame, provided
that the data does not contain any simulated frame alignment words.
The terminal equipment shall continue to maintain frame alignment in the event of receiving one or two
consecutive incorrect frame alignment signals. On receipt of three consecutive incorrect frame alignment
signals the terminal equipment shall consider frame alignment to have been lost and initiate a search for
frame alignment.
Frame alignment may also be considered to have been lost following:
d) the occurrence of = 915 errored SMFs out of 1 000 SMFs; or
e) bit 2 in frames not containing the frame alignment signal being in error on three consecutive
occasions; or
f) the inability to achieve multiframe alignment within 8 ms (see subclause 4.2.2.9.2).
Test: The test shall be conducted in accordance with subclause A.2.10.1.
4.2.2.9.2 Multiframe alignment
This requirement is optional and applies only to those terminal equipments needing to obtain multiframe
alignment in order to extract CRC-4 information in order to comply with subclause 4.2.1.8.2.2.
Requirement: CRC-4 multiframe alignment shall be achieved if at least two valid CRC-4 multiframe
alignment signals can be located within 8 ms (the time separating two CRC-4 multiframe alignment
signals being 2 ms or a multiple of 2 ms). If multiframe alignment cannot be achieved within 8 ms it shall
be assumed that frame alignment is due to a spurious frame alignment signal and a research for frame
alignment shall be initiated.
NOTE: The research for frame alignment should be started at a point just after the location of
the assumed spurious frame alignment signal. This will usually avoid realignment onto
the spurious frame alignment signal.
Test: The test shall be conducted in accordance with subclause A.2.10.2.
4.3 Safety
4.3.1 General requirements
Requirement: The terminal equipment interface shall comply with the requirements for accessible parts
of a Safety Extra-Low Voltage (SELV) circuit.
Test: The test shall be conducted according to EN 60950 [5].
NOTE: Designers should take into account the minimum impedance towards ground specified
in this ETS.
4.3.2 Touch current
This requirement recognizes the fact that the terminal equipment is likely to have a mains electricity supply
interface. If the terminal equipment does not have a mains supply, this requirement is not applicable.
For the purpose of the following requirement, the term referred to as I in ETS 300 046-2 [6] shall be
a
deemed to be the point of test referred to in subclause A.1.2.
Requirement: The touch current measured across the terminal equipment interface shall not exceed
0,25 mA.
Test: The test shall be conducted according to ETS 300 046-2 [6].
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ETS 300 420: November 1995
4.4 Overvoltage protection
Overvoltage protection shall be in accordance with the methods described in ETS 300 046-3 [7] as
detailed below. The compliance criteria for the overvoltage protection tests of subclauses 4.4.1 to 4.4.4
shall be:
The terminal equipment shall operate properly within the limits of this specification after the test
without:
- the need for resetting the fault protection facilities; or
- the need to change any hardware component; or
- reloading of data other than data of a type declared in the operating instructions to be
unprotected data.
For the purpose of the following subclauses on protection, the term "interface" refers to the connection
made by the terminal equipment to the leased line.
For the purpose of the following subclauses on protection, the term referred to as I in ETS 300 046-3 [7]
a
shall be deemed to be the point of test referred to in subclause A.1.2.
4.4.1 Surge simulation, common mode
Requirement: The interface shall meet the compliance criteria after 10 common mode surges of 1 kV
(1,2/50 μs) on the terminal equipment interface.
Test: The test shall be conducted according to subclause 5.5.1 of ETS 300 046-3 [7].
4.4.2 Surge simulation, transverse mode between transmit and receive pairs
Requirement: The interface shall meet the compliance criteria after 10 transverse mode surges of 250 V
(1,2/50 μs) on the terminal equipment interface between the transmit and receive pairs.
Test: The test shall be conducted according to subclause 5.5.2 of ETS 300 046-3 [7].
4.4.3 Mains simulation, common mode
Requirement: If the terminal equipment is supplied from the mains, the interface shall meet the
compliance criteria after 10 common mode surges of 2,5 kV (10/700 μs).
Test: The test shall be conducted according to subclause 5.6.1 of ETS 300 046-3 [7].
4.4.4 Mains simulation, transverse mode
Requirement: If the terminal equipment is supplied from the mains, the interface shall meet the
compliance criteria after 10 transverse mode surges of 2,5 kV (10/700 μs).
Test: The test shall be conducted according to subclause 5.6.2 of ETS 300 046-3 [7].
4.4.5 Impulse transfer from mains, common mode
Requirement: If the interface is supplied from the mains, it shall transfer less than 1 kV common mode
voltage and less than 250 V transverse voltage to the terminal equipment interface when a common mode
surge of either polarity and of 2,5 kV (10/700 μs) is applied to the mains supply port.
Test: The test shall be conducted according to subclause 5.7.1 of ETS 300 046-3 [7].
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ETS 300 420: November 1995
4.4.6 Impulse transfer from mains, transverse mode
Requirement: If the interface is supplied from the mains, it shall transfer less than 1 kV common mode
voltage and less than 250 V transverse voltage to the terminal equipment interface when a transverse
mode surge of either polarity and of 2,5 kV (10/700 μs) is
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