ETSI TS 101 952-1 V1.1.1 (2009-06)

Access network xDSL splitters for European deployment; Part 1: Generic specification of xDSL over POTS splitters

RTS/ATTM-06021

General Information

• Status: Published
• Publication Date: 10-Jun-2009
• Technical Committee: ATTM TM6 - Wireline Access Network Systems
• Current Stage: 12 - Completion
• Due Date: 15-Apr-2009
• Completion Date: 11-Jun-2009

Standards Content (Sample)

Technical Specification
Access network xDSL splitters
for European deployment;
Part 1: Generic specification of xDSL
over POTS splitters
2 ETSI TS 101 952-1 V1.1.1 (2009-06)

Reference
RTS/ATTM-06021
Keywords
ADSL, POTS, splitter, VDSL
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ETSI
3 ETSI TS 101 952-1 V1.1.1 (2009-06)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 7
1 Scope . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 9
3 Definitions, symbols and abbreviations . 10
3.1 Definitions . 10
3.2 Symbols . 11
3.3 Abbreviations . 12
4 General functional description of xDSL over POTS splitters . 13
4.1 Functional diagram . 13
4.2 High pass block: three alternatives . 14
5 Circuit definitions, testing conditions and methods . 14
5.1 DC testing conditions . 14
5.1.1 Polarity independence . 14
5.1.2 DC feeding conditions (on/off-hook) . 14
5.1.3 DC feeding and loading bridges . 15
5.2 AC terminating impedances Z . 16
AC
5.2.1 Z and Z , xDSL transceiver related impedances . 16
RefDSL DSL
5.2.2 Z and Z , off-hook impedances . 16
R SL
5.2.3 Z , xDSL band impedance . 17
RHF
5.2.4 Z , on-hook high impedance . 17
OnHI
5.2.5 Z , on-hook low impedance . 17
OnLI
5.2.6 Z , impedance on-hook . 17
OnHo
5.2.7 Z , load impedance for ringing . 18
Ring
5.2.8 Z , impedance of the metering device . 18
Meter
5.3 High pass filter implementation . 18
5.3.1 High pass filter alternative B: First order filter . 18
5.3.2 High pass filter alternative C: higher order filter . 19
5.3.3 Reference high pass filter . 19
5.4 General transmission test set-up . 19
5.4.1 General definition of the Insertion Loss (IL) measurement . 20
5.4.2 POTS signal loss: IL LINE port to POTS port . 20
5.4.3 xDSL signal isolation: IL LINE to POTS port or xDSL to POTS port . 21
5.4.4 xDSL signal loss: IL LINE port to xDSL port . 21
5.4.5 General definition of the Return Loss . 23
5.4.6 Return Loss test set-up at LINE port and POTS port . 24
5.5 Unbalance measurement . 24
5.5.1 General definition of Longitudinal Conversion Loss . 24
5.5.2 General definition of Longitudinal Conversion Transfer Loss . 25
5.5.3 LCL and LCTL test set-up . 25
5.6 Noise measurement . 26
5.6.1 Psophometric noise in the POTS Band . 26
5.6.2 Noise in the xDSL Band . 27
5.7 Common Mode Rejection Ratio measurement . 27
6 Splitter requirements . 27
6.1 Options for splitter requirements . 27
6.1.1 Option A splitters . 28
6.1.2 Option B splitters . 28
6.2 DC requirements . 28
ETSI
4 ETSI TS 101 952-1 V1.1.1 (2009-06)
6.2.1 DC resistance to earth . 28
6.2.2 DC insulation resistance between A-wire and B-wire . 29
6.2.3 DC series resistance R . 29
DC
6.2.4 DC signalling . 29
6.3 Ringing frequency requirements . 29
6.3.1 Ringing voltage drop at 25 Hz and 50 Hz . 30
6.3.2 Z impedance in the presence of ringing at 25 Hz and 50 Hz . 30
InRing
6.3.3 Total harmonic distortion at 25 Hz and 50 Hz . 30
6.4 POTS pass band loss requirements (on-hook) . 30
6.4.1 On-hook requirement for the case of high impedance termination . 31
6.4.2 On-hook requirement for the case of low impedance termination . 31
6.4.2.1 Low impedance on-hook POTS pass band insertion loss. 31
6.4.2.2 Low impedance on-hook POTS pass band insertion loss distortion . 31
6.5 POTS pass band loss requirements (off-hook) . 31
6.5.1 Off-hook POTS pass band insertion loss . 32
6.5.2 Off-hook POTS pass band insertion loss distortion . 32
6.6 POTS pass band return loss requirements (off-hook) . 32
6.6.1 POTS pass band return loss requirements, option A . 32
6.6.2 POTS pass band return loss requirements, option B . 32
6.7 Requirements relating to metering pulses at 12 kHz or 16 kHz (optional). 33
6.8 Unbalance about Earth . 33
6.8.1 Unbalance of the low pass part . 33
6.8.2 Unbalance of the high pass part for alternative B or C . 34
6.9 xDSL band requirements . 34
6.9.1 xDSL band on-hook isolation between LINE and POTS port . 35
6.9.2 xDSL band off-hook isolation between LINE and POTS port . 35
6.9.3 Transition band signal loss: IL between POTS port and LINE port (optional) . 36
6.9.4 xDSL signal loss: IL LINE port to xDSL port . 36
6.9.4.1 High pass alternatives A and B . 36
6.9.4.2 High pass alternative C . 37
6.10 Noise levels . 37
6.10.1 POTS band audible noise level . 37
6.10.2 xDSL band noise level . 37
6.11 Distortion . 37
6.11.1 POTS band intermodulation distortion . 37
6.11.2 Extended xDSL band intermodulation distortion (informative) . 38
6.12 Group delay distortion . 38
6.13 POTS transient effects (informative) . 38
6.14 Requirements for Common Mode Rejection (optional) . 39
6.15 Requirements for Crosstalk at the LE (optional) . 39
Annex A (normative): xDSL specific information . 40
A.1 Z and Z for specific xDSL over POTS variants . 40
DSL RefDSL
A.1.1 Generic definition of Z , using C , Z , C and L . 40
DSL DCB RefDSL DSL DSL
A.1.2 Z for ADSL over POTS . 41
DSL
A.1.3 Z for European VDSL1 over POTS, with US0 starting at 25 kHz . 42
DSL
A.1.4 Z for VDSL2 over POTS with US0 . 42
DSL
A.2 Common requirements for passive POTS splitters . 43
A.3 Specific requirements for passive splitters for ADSL over POTS variants. 45
A.4 Specific requirements for passive splitters for VDSL1 over POTS variants. 46
A.5 Specific requirements for passive splitters for VDSL2 over POTS variants at the TE side . 46
A.6 Specific requirements for passive splitters for VDSL2 over POTS variants at the LE side . 47
Annex B (informative): Evolution of the documents . 48
Annex C (informative): Use of the present document for splitters at the cabinet . 49
Annex D (informative): Intrinsic IL and RL caused by Z in the POTS band. 50
DSL
ETSI
5 ETSI TS 101 952-1 V1.1.1 (2009-06)
Annex E (informative): IL Measurement from LINE to xDSL inside Z . 51
DSL
Annex F (informative): Return Loss measurements: practical diagrams. 53
Annex G (informative): Insertion Loss measured with feeding and loading bridges . 54
Annex H (informative): Dynamic tests of splitters in the presence of xDSL transceivers (WT-
127 of the Broadband Forum) . 55
H.1 General description. 55
H.2 Detailed description . 56
H.2.1 Static tests under continuous signals according to WT-127 . 57
H.2.2 Dynamic tests according to WT-127 . 57
Annex I (informative): Optimal transmission of POTS and xDSL signals and their
separation . 58
Annex J (informative): More on feeding and loading bridges . 60
Annex K (informative): Additional requirements for Active Splitter (F.F.S.) . 61
K.1 Bidirectional IL tests . 61
K.2 Noise measurements methods for active splitters . 61
K.2.1 (5.6.1) Psophometric noise in the POTS Band . 61
K.2.2 (5.6.2) Noise in the xDSL Band . 61
K.3 (6.10) Noise requirements for active splitters . 61
K.3.1 (6.10.1) POTS band audible noise level . 62
K.3.2 (6.10.2) xDSL band noise level . 62
K.4 (6.11) Distortion . 62
K.5 (6.13) Transitional tests . 62
Annex L (informative): Bibliography . 63
History . 64

ETSI
6 ETSI TS 101 952-1 V1.1.1 (2009-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Access, Terminals, Transmission
and Multiplexing (ATTM).
The present document is part 1 of a multi-part deliverable covering Access network xDSL splitters for European
deployment, as identified below:
Part 1: "Generic specification of xDSL over POTS splitters";
Part 2: "Generic specification of xDSL over ISDN splitters and xDSL universal splitters";
Part 3: "Generic specification of distributed filters for xDSL over POTS";
Part 4: "Additional specifications for dynamic distributed filters for xDSL over POTS".
NOTE 1: Before the publication of the 3 or 4 parts as described above, the TS 101 952 was composed of 2 parts,
which discriminated between ADSL and VDSL, with several subparts. For reasons of simplicity the TS is
now restructured as a set of only 3 (potentially 4) documents, intended for both ADSL and VDSL when
applicable. The older structure of the documents is explained in the informative annex B.
NOTE 2: Useful information on splitter tests may be found in TR 101 953-1-1 [i.3], TR 101 953-1-2 [i.4],
TR 101 953-2-1 [i.5] and TR 101 953-2-2 [i.6]. These documents are linked to the previous versions of
the splitter specifications. [i.3], [i.4], [i.5] and [i.6] e.g. describe the combination of the AC testing
conditions of the test set-ups with the DC conditions controlled via feeding and loading bridges. If there is
a discrepancy between the present document and the older TR 101 953 series of documents, the present
document prevails.
NOTE 3: The use of distributed filters is not recommended for VDSL but it is not excluded. For this reason parts 3
and 4 refer to distributed filters for xDSL and not just for ADSL.
The present document is fully in line with initiative "eEurope 2002 - An Information Society For All", under "The
contribution of European standardization to the eEurope Initiative, A rolling Action Plan" especially under the key
objective of a cheaper, faster and secure Internet.
ETSI
7 ETSI TS 101 952-1 V1.1.1 (2009-06)
Introduction
Remarks on and limitations of the present document
The present document covers all xDSL system variants, such as ADSL, ADSL2, ADSL2plus, VDSL1 and VDSL2. It is
applicable at the Local Exchange (LE) (i.e. network) side of the line at the LE or at the cabinet and at the Terminal
Equipment (TE) (i.e. user) side of the line. A number of limitations and remarks should be listed:
1) The use of the present documents is extended to splitters at the cabinet. Indeed, the previous versions of the
present document clearly stated that they did not apply to splitters at the cabinet. However as explained in the
informative annex C, this restriction was lifted.
2) The present document does not contain the requirements for splitters, which can handle both POTS and ISDN.
These so-called xDSL over "ISDN or POTS" universal splitters are specified in part 2.
3) Splitters at the customer premises with a distributed topology, called distributed filters, are not within the
scope of the present document. They are described in part 3 (and potentially part 4).
4) The present document covering xDSL over POTS splitters was gained from the experience with passive and
static xDSL splitters, the original state of the art for this application. Furthermore, the experience was gained
with identical requirements at either side of the line. Therefore, the requirements in the present document are
primarily intended for passive and static filters, with identical requirements for the LE side and the TE side of
the line. However, in the note under table A.3 an optional diversification between splitters requirements at the
two sides of the line is described. For the TE side splitters an optional variant could be allowed with better
downstream protection, with less IL in the upstream band and more IL in the downstream band. Similar
differentiation between LE and TE is possible for the balance requirements, see the note under table A.10.
5) The present document covering xDSL over POTS splitters is limited to passive and static splitters. There are
other classes of filters possible, besides passive and static splitters. Such active and/or dynamic filters are
composed of other elements than passive components. Active/dynamic splitters require different and
additional requirements and test methods to be specified. The full specification of requirements for
active/dynamic splitter is F.F.S. An introduction to this is in the informative annex K.
6) For certain static properties in the present document it is possible to relax the requirements and prove in
dynamic tests that the splitter performs sufficiently well. These dynamic tests are compiled in WT-127, by the
Broadband Forum. The use of the WT-127 methodology for this purpose is outside the scope of this version of
the document, but could prove useful to introduce splitters with reduced complexity, or active and/or dynamic
splitters. The WT-127 methodology is not fully finalized. It is described in annex H. Finalizing splitter tests in
the present document based on WT-127 is F.F.S.
7) To test distortion, noise and other requirements in the present document the WT-127 methodology is sometime
a superior methodology, or even the only feasible method at an acceptable complexity. Indeed, WT-127 will
prove that a splitter works correctly in a worst case xDSL test environment. With such tests, based on actual
xDSL transceiver results, one can avoid requirements are either inadequate or potentially unnecessarily strong.
Defining splitter tests based on WT-127 in the present document is F.F.S.
ETSI
8 ETSI TS 101 952-1 V1.1.1 (2009-06)
1 Scope
The present document specifies requirements and test methods for the low pass and high pass part of xDSL over POTS
splitters. These splitters are intended to be installed at the LE (i.e. network) side of the local loop, either at the local
exchange or at a remote cabinet, and at the TE (i.e. user) side near the NTP. When used at the remote cabinet, the POTS
signals can be injected locally at the cabinet, or at the central office. In the case of splitters at the TE side, the present
document specifies the central splitter that is intended for use at the demarcation point of the customer premises.
The majority of requirements in the present document are generic and applicable to all xDSL over POTS central
splitters. In the case where any requirements are applicable to only one particular flavour of xDSL, this is clearly
indicated in the clause describing the requirement. The relevant information about requirements for specific xDSL
system variants is given in annex A.
The splitter filter, as specified by the present document, may be implemented as an independent unit, separately from
the xDSL transceiver, or may be integrated with the xDSL termination unit. The splitter may also be integrated with the
base band termination unit (e.g. POTS line card); however this is outside of the scope of the present document.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
[1] ETSI TBR 038: "Public Switched Telephone Network (PSTN); Attachment requirements for a
terminal equipment incorporating an analogue handset function capable of supporting the justified
case service when connected to the analogue interface of the PSTN in Europe".
[2] ITU-T Recommendation O.42: "Equipment to measure non-linear distortion using the 4-tone
intermodulation method".
[3] ETSI ES 203 021-3: "Access and Terminals (AT); Harmonized basic attachment requirements for
Terminals for connection to analogue interfaces of the Telephone Networks; Update of the
technical contents of TBR 021, EN 301 437, TBR 015, TBR 017; Part 3: Basic Interworking with
the Public Telephone Networks".
NOTE: ETSI TBR 021 has been made historical.
[4] ITU-T Recommendation O.41: "Psophometer for use on telephone-type circuits".
ETSI
9 ETSI TS 101 952-1 V1.1.1 (2009-06)
[5] ITU-T Recommendation O.9: "Measuring arrangements to assess the degree of unbalance about
earth".
[6] ETSI ES 201 970: "Access and Terminals (AT); Public Switched Telephone Network (PSTN);
Harmonized specification of physical and electrical characteristics at a 2-wire analogue presented
Network Termination Point (NTP)".
[7] ETSI EN 300 659 (all parts): "Access and Terminals (AT); Analogue access to the Public
Switched Telephone Network (PSTN); Subscriber line protocol over the local loop for display
(and related) services".
[8] ETSI ES 200 778 (all parts): "Access and Terminals (AT); Analogue access to the Public Switched
Telephone Network (PSTN); Protocol over the local loop for display and related services;
Terminal equipment requirements".
[9] ETSI ES 201 729: "Public Switched Telephone Network (PSTN); 2-wire analogue voice band
switched interfaces; Timed break recall (register recall); Specific requirements for terminals".
[10] ETSI ES 201 187: "2-wire analogue voice band interfaces; Loop Disconnect (LD) dialling specific
requirements".
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI TR 102 139: "Compatibility of POTS terminal equipment with xDSL systems".
[i.2] ETSI TR 101 728: "Access and Terminals (AT); Study for the specification of low pass filter
section of POTS/ADSL splitters".
[i.3] ETSI TR 101 953-1-1: "Access and Terminals (AT); Unified and Generic Testing Methods for
European Specific DSL splitters; Part 1: ADSL splitters for European deployment;
Sub-part 1: Specification of Testing methods for Low Pass part of ADSL/POTS splitters".
[i.4] ETSI TR 101 953-1-2: "Access network xDSL transmission filters; Part 1: ADSL splitters for
European deployment; Sub-part 2: Testing methods for High Pass part of ADSL/POTS splitters".
[i.5] ETSI TR 101 953-2-1: "Access network xDSL transmission filters; Part 2: VDSL splitters for
European deployment; Sub-part 1: Specification of Testing methods for low pass part of
VDSL/POTS splitters".
[i.6] ETSI TR 101 953-2-2: "Access network xDSL transmission filters; Part 2: VDSL splitters for
European deployment; Sub-part 2: Specification of Testing methods for high pass part of
VDSL/POTS splitters".
[i.7] ITU-T Recommendation G.993.1: "Very high speed digital subscriber line transceivers".
[i.8] ITU-T Recommendation G.993.2: "Very high speed digital subscriber line transceivers 2
(VDSL2)".
[i.9] ITU-T Recommendation G.992.1: "Asymmetric digital subscriber line (ADSL) transceivers".
[i.10] ITU-T Recommendation G.992.3: "Asymmetric digital subscriber line transceivers 2 (ADSL2)".
[i.11] ITU-T Recommendation G.992.5: "Asymmetric Digital Subscriber Line (ADSL) transceivers -
Extended bandwidth ADSL2 (ADSL2plus)".
[i.12] ETSI TS 101 952-2: "Access network xDSL splitters for European deployment; Part 2: Generic
specification of xDSL over ISDN splitters and xDSL universal splitters".
NOTE: Part 2 of this multipart deliverable is under construction. Part 1 is the present document.
ETSI
10 ETSI TS 101 952-1 V1.1.1 (2009-06)
[i.13] ETSI TS 101 952-3: "Access network xDSL splitters for European deployment; Part 3: Generic
specification of distributed filters for xDSL over POTS";
NOTE: Part 3 of this multipart deliverable is under construction. Part 1 is the present document.
[i.14] ETSI TS 101 952-4: "Access network xDSL splitters for European deployment; Part 4: Additional
specifications for dynamic distributed filters for xDSL over POTS".
NOTE: Part 4 of this multipart deliverable is under study. Part 1 is the present document.
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
A-wire and B-wire: wires in the 2-wire local loop connection provided from the exchange to the NTP
active splitters: splitters containing some active components, including splitters with "on/off-hook detection" circuitry
distributed filter: low pass filter that is added in series with each of the parallel connected POTS TEs
NOTE: Each of these parallel connected filters (in the in-house cabling) is known as a distributed filter. These
filters are also known as In-line filters or microfilters.
dynamic splitter: splitter changing its transfer behaviour dynamically, e.g. based on the state of the POTS connection
far end echo: speech that is fed back to the talker in a telephony connection with a round trip delay (i.e. the delay
between talking and hearing the feedback), of greater than 5 ms, resulting in a distinguishable echo
off-hook: state of the POTS equipment at either end of a loop connection when the NTP terminal equipment is in the
steady loop state
NOTE: See ES 203 021-3 [3].
on-hook: state of the POTS equipment at either end of a POTS loop connection when the NTP terminal equipment is in
the quiescent state
NOTE 1: See ES 203 021-3 [3].
NOTE 2: In the case where multiple TEs are present at the customer end of the loop, then the TE is considered to
be on-hook from the perspective of testing the splitter only when all of terminals are on-hook.
passive splitters: splitters containing exclusively passive components
sidetone: speech that is fed back to the talker in a telephony connection with a round trip delay (i.e. the delay between
talking and hearing the feedback), of less than approximately 5 ms, making it indistinguishable from the original
utterance
signature network: circuitry included at the POTS port of the splitter, the values and configuration of which may be
operator dependent, which has the purpose of enabling network operator's remote line testing equipment to determine
the presence of a splitter on a line
xDSL: ADSL or VDSL
NOTE: This abbreviation stands for ADSL or VDSL and its use this way is strictly limited to the present
document; e.g. HDSL, SDSL and SHDSL are not covered.
ETSI
11 ETSI TS 101 952-1 V1.1.1 (2009-06)
3.2 Symbols
For the purposes of the present document, the following symbols apply:
Att Attenuation in the xDSL Band (LINE port to xDSL port, or reversed)
DB
C DC Blocking capacitor as the optional high pass of first order
DCB
C The capacitor C part of the Z
DSL
DSL
f highest of the used frequencies in the xDSL Band
H
f lowest of the used frequencies in the xDSL Band
L
f intermediate frequency, at the US(0) to DS edge for xDSL
M1
f intermediate frequency, used for IL in on-hook
M2
f maximum frequency above xDSL band for measurements
Max
IL Insertion Loss xDSL Band Off-Hook
DBOffH
IL Insertion Loss (Isolation) xDSL Band On-Hook
DBOnH
IL Insertion Loss for Metering (Off-Hook)
Meter
IL Insertion Loss POTS Pass Band Off-Hook
PBOffH
IL Insertion Loss POTS Pass Band On-Hook
PBOnH
IL Insertion Loss Transition Band, only done in Off-Hook
TBOffH
LCL Longitudinal Conversion Loss
LCTL Longitudinal Conversion Transfer Loss
L The inductance L part of the Z
DSL
DSL
N Noise in the xDSL band
DB
N Noise in the POTS band (psophometric)
PB
R DC resistance between A and B wire
A to B wire
R DC Resistance of a splitter for POTS current
DC
R The resistive R part of the Z (R ≡ Z )
DSL DSL DSL RefDSL
R Variable DC feed resistor in figure 3
FEED
R Variable DC load resistor in figure 4
LOAD
RL Return Loss POTS Pass Band Off-Hook, option A or B
PBOffH
R Resistance to Earth
to Earth
S Switch to connect xDSL impedance Z to the test set-up
DSL DSL
UaE Unbalance about Earth
V V Ring-Drop
RD
Z Generic name for the AC POTS impedance models
AC
Z Impedance model of the input filter of a particular xDSL
DSL
Z The input impedance of the splitter at the ringing frequencies
InRing
Z Generic name of the POTS on-hook impedance
ON
Z Impedance modelling POTS On-hook with High Impedance
OnHI
Z Impedance modelling multiple parallel on-hook phones
OnHo
Z Impedance modelling POTS On-hook with Low Impedance
OnLI
Z European harmonized complex reference POTS impedance
R
Z Generic name of Reference POTS impedance in RL formula
Ref
Z Nominal Reference Design Impedance of xDSL (Z ≡ R )
RefDSL RefDSL DSL
Z Complex POTS impedance, extending Z to higher frequencies, [i.1]
RHF R
Z Impedance modelling the load represented by ringer circuits
Ring
Z Impedance Z Short Loop, modelling a short line terminated on 600 Ω
SL
ETSI
12 ETSI TS 101 952-1 V1.1.1 (2009-06)
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
ADSL Asymmetric Digital Subscriber Line
ADSL1 ADSL limited to 1,1 MHz, see ITU-T Recommendation G.992.1 [i.9]
ADSL2 ADSL revision 2, see ITU-T Recommendation G.992.3 [i.10]
ADSL2plus ADSL revision "2plus", extended to 2,2 MHz; see ITU-T Recommendation G.992.5 [i.11]
AWGN Additive White Gaussian Noise
CLIP Calling Line Identification Presentation
CMRR Common Mode Rejection Ratio
CO Central Office ( ≡ Local Exchange ≡ LE)
CPE Customer Premise Equipment ( ≡ Terminal Equipment ≡ TE)
DC Direct Current
DS Downstream, which is from LE side to TE side
DSL Digital Subscriber Line
DSLAM DSL Access Module, equipment at the LE side with multiple xDSL transceivers
DUT Device Under Test
e.m.f. Electro-Magnetic Force
F.F.S. For Further Study
FDD Frequency Division Duplexing
HPF High Pass Filter
IL Insertion Loss
ISDN Integrated Services Digital Network
ITU International Telecommunication Union
LE Local Exchange ( ≡ Central Office)
N.A. Not Applicable
NTP Network Termination Point
POTS Plain Old Telephone Service
NOTE: The abbreviation POTS is used in the text of the present document instead of PSTN.
PSTN Public Switched Telephone Network
NOTE: The abbreviation PSTN is replaced by POTS in the text of the present document.
RL Return Loss
RMS Root Mean Square
SLIC Subscriber Line Interface Circuit
SDSL Symmetric DSL
TBD To Be Determined
TE Terminal Equipment (e.g. Telephone, Fax, voice band modem, etc.)
THD Total Harmonic Distortion
UaE Unbalance about Earth
US Upstream, which is from TE side to LE side
US0 US (Upstream) "0" band, the lowest VDSL upstream band
VDSL Very high speed Digital Subscriber Line
VDSL1 VDSL variant defined in ITU-T Recommendation G.993.1 [i.7]
VDSL2 VDSL variant defined in ITU-T Recommendation G.993.2 [i.8]
NOTE: xDSL is defined under clause 3.1 with definitions.
ETSI
13 ETSI TS 101 952-1 V1.1.1 (2009-06)
4 General functional description of xDSL over POTS
splitters
The main purpose of the xDSL over POTS splitter is to separate the transmission of POTS signals and xDSL signals,
enabling the simultaneous transmission of both services on the same twisted pair. The splitter also serves to protect
POTS from interference due to ingress from xDSL signals. Equally it protects the xDSL transmission from transients
generated primarily during POTS signalling (dialling, ringing, ring trip, etc.), and it must also prevent interference to
the xDSL service due to fluctuations in impedance and linearity that occur when telephones change operational state
(e.g. from off-hook to on-hook). Information on various implementations of ADSL over POTS splitters is given in
TR 101 728 [i.2]. Insertion of a splitter filter in existing POTS lines shall only have a low impact on the performance of
the POTS service. A tutorial on the transmission and separation of POTS and xDSL signals is contained in annex I.
4.1 Functional diagram
The functional diagram for the splitter combination is given in figure 1.

NOTE: For a Local Exchange xDSL deployment, the length "X" in this figure will typically be far less than 1 km.
For a remote xDSL terminal deployment, the length "X" can be up to several kilometres.

Figure 1: Functional diagram of the xDSL splitter configuration
The types of transfer functions between the different ports of the splitter are shown in figure 2 and can be understood as
follows:
- The transfer function from the POTS port to the LINE port and vice-versa is that of a low pass filter.
- A high level of isolation is required from the xDSL port to the POTS port to prevent undesirable interaction
between the xDSL transmission and any existing narrowband services, i.e. in both directions.
- The transfer function from the xDSL port to the LINE port and vice-versa is either that of a high pass filter, or
it may be all pass in nature, in the case where the full high pass filter function is implemented in the xDSL
transceiver.
Figure 2: Structure of the xDSL splitter filter
ETSI
14 ETSI TS 101 952-1 V1.1.1 (2009-06)
4.2 High
...