ETSI ETS 300 117 ed.1 (1991-06)

SLOVENSKI STANDARD
SIST ETS 300 117 E1:2003
01-december-2003
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Attachments to the Public Switched Telephone Network (PSTN); Category II attachment
requirements for 2400 bits per second duplex modems standardized for use on the
PSTN (Candidate NET 23)
Ta slovenski standard je istoveten z: ETS 300 117 Edition 1
ICS:
33.040.35 Telefonska omrežja Telephone networks
SIST ETS 300 117 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 117 E1:2003

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SIST ETS 300 117 E1:2003
EUROPEAN ETS 300 117
TELECOMMUNICATION June 1991
STANDARD
Source: Reference:
ICS:33.020
PSTN, 2400 bits/second duplex modems
Key words:
Attachments to the Public Switched Telephone Network (PSTN)
Category II attachment requirements for 2400 bits per second
duplex modems standardized for use on the PSTN
(The text of this ETS may be utilized, wholly or in part,
for the establishment of NET 23)
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 1991. All rights reserved.
New presentation - see History box

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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 Standards Approval Dept." at the address shown on the title page.

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Contents
Foreword.7
1 Scope .9
2 Normative references .9
3 Definitions and abbreviations. 10
3.1 Definitions. 10
3.2 Abbreviations. 11
4 General requirements . 11
4.1 References to other ETSs . 11
4.2 Information to be provided by the applicant . 11
4.2.1 Information required for testing purposes . 11
4.2.2 Instructions for use. 12
5 Functional requirements specific to Category II modems . 12
5.1 General requirements. 12
5.2 Modes. 12
5.3 Line signals. 13
5.3.1 Carrier frequencies. 13
5.3.2 Guard tone . 13
5.3.2.1 Guard tone - call mode modem. 13
5.3.2.2 Guard tone - answer mode modem. 13
5.3.3 Transmitted spectrum. 14
5.4 Line signalling rates. 14
5.5 Encoding and decoding of data . 14
5.6 Threshold of the received line signal detector . 14
5.7 Channel allocation . 14
5.7.1 Channel selection . 14
5.7.2 Automatic channel selection . 15
5.8 Hand-shaking sequences . 15
5.8.1 Auto-calling and auto-answering procedures. 15
5.8.1.1 Auto-calling - calling tone. 15
5.8.1.2 Auto-calling - recognition of answering tone . 15
5.8.1.3 Auto-answering . 15
5.8.2 Start-up procedures . 15
5.8.2.1 Call mode modem. 15
5.8.2.1.1 AMM set to 2400 bit/s (CCITT
Recommendation V.22bis [7]) . 16
5.8.2.1.2 AMM set to 1200 bit/s (CCITT
Recommendation V.22 [6] or V.22bis
[7]). 16
5.8.2.2 Answer mode modem . 16
5.8.2.2.1 CMM set to 2400 bit/s (CCITT
Recommendation V.22bis [7]) . 17
5.8.2.2.2 CMM set to 1200 bit/s. 17
5.8.3 Retrain sequence (2400 bit/s operation). 18
5.8.3.1 Initiating signal. 18
5.8.3.2 Response signal . 18
5.8.4 Rate change request . 18
5.8.4.1 2400 bit/s to 1200 bit/s . 19
5.8.4.1.1 Instigation of a rate change. 19
5.8.4.1.2 Response to a request for rate change 19

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5.8.4.2 1200 bit/s to 2400 bit/s .20
5.8.4.2.1 Instigation of a rate change.20
5.8.4.2.2 Response to a request for rate change 20
5.9 Transmission of start-stop characters.20
5.10 Scrambler and de-scrambler .21
5.11 Test loop 2 .21
5.11.1 Instigation of a remote loop 2 .21
5.11.2 Termination of a remote loop 2 .22
5.12 Receiver performance.22
Annex A (normative): Testing methods .23
A.1 General testing conditions.23
A.1.1 General notes .23
A.1.2 Proposed order for performing the tests .23
A.1.3 Limitation of number of tests .24
A.1.3.1 Introduction.24
A.1.3.2 General rules . 25
A.1.3.3 Specific rules .25
A.2 Test for subclause 5.3.1 (Carrier frequencies) .25
A.2.1 Test for subclause 5.3.1 using the MCT.26
A.2.2 Test for modems where the scrambler can be inhibited.26
A.2.3 Tests for modems where test points are accessible.26
A.2.4 Test for modems where neither subclauses A.2.2 nor A.2.3 applies .26
A.3 Test for subclause 5.3.2 (Guard tone).26
A.3.1 Test for subclause 5.3.2.1 (Guard tone, call mode modem).26
A.3.2 Test for subclause 5.3.2.2 (Guard tone, answer mode modem).27
A.4 Test for subclause 5.4 (Line signalling rates) .27
A.5 Test for subclause 5.5 (Encoding and decoding of data).27
A.6 Test for subclause 5.6 (Threshold of received line signal detector) .27
A.7 Test for subclause 5.7 (Channel allocation).28
A.7.1 Test for subclause 5.7.1 (General) .28
A.7.2 Test for subclause 5.7.2 (Automatic channel selection).28
A.8 Test for subclause 5.8 (Hand-shaking sequences).29
A.8.1 Tests for subclause 5.8.2 (Start-up procedures).29
A.8.1.1 Test for subclause 5.8.2.1 (Call mode modem under test) .29
A.8.1.1.1 Test for subclause 5.8.2.1.1 (CMM calling a CCITT
Recommendation V.22bis [7] AMM at 2400bit/s).29
A.8.1.1.2 Test for subclause 5.8.2.1.2 (CMM calling a CCITT
Recommendation V.22 [6] or V.22bis [7] AMM at 1200
bit/s).29
A.8.1.2 Test for subclause 5.8.2.2 (Answer mode modem under test).30
A.8.1.2.1 Test for subclause 5.8.2.2.1 (AMM called by a CCITT
Recommendation V.22bis [7] CMM at 2400 bit/s).30
A.8.1.2.2 Test for subclause 5.8.2.2.2 (AMM called by a CCITT
Recommendation V.22 [6] or V.22bis [7] CMM at 1200
bit/s).30
A.8.2 Tests for subclause 5.8.3 (Retrain sequence).30
A.8.2.1 Tests for subclause 5.8.3.1 (Initiating signal) .31
A.8.2.2 Tests for subclause 5.8.3.2 (Response signal).31
A.8.3 Tests for subclause 5.8.4 (Rate change request).31
A.8.3.1 Tests for subclause 5.8.4.1 (2400 bit/s to 1200 bit/s).31

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A.8.3.1.1 Tests for subclause 5.8.4.1.1 (Instigation of a rate change
from 2400 bit/s to 1200 bit/s) . 32
A.8.3.1.2 Tests for subclause 5.8.4.1.2 (Response to a request for
a rate change from 2400 bit/s to 1200 bit/s) . 32
A.8.3.2 Tests for subclause 5.8.4.2 (1200 bit/s to 2400 bit/s). 33
A.8.3.2.1 Tests for subclause 5.8.4.2.1 (Instigation of a rate change
from 1200 bit/s to 2400 bit/s) . 33
A.8.3.2.2 Tests for subclause 5.8.4.2.2 (Response to a request for
a rate change from 1200 bit/s to 2400 bit/s) . 34
A.9 Test for subclause 5.10 (Scrambler and de-scrambler) . 34
A.9.1 Test for modems which can be operated in the synchronous mode of use:. 35
A.9.2 Test for modems which can only be operated in a asynchronous mode of use . 35
A.10 Test for subclause 3.11 (Test loop 2) . 36
A.10.1 Instigation of remote test loop 2 . 36
A.10.1.1 Transmission of the test loop initiation signal (Controlling modem under
test). 36
A.10.1.2 Response to the test loop initiation signal (Controlled modem under test ) . 36
A.10.2 De-activation of remote test loop 2. 36
A.10.2.1 Transmission of the de-activation signal (Controlling modem under test) . 36
A.10.2.2 Response to the de-activation signal (Controlled modem under test) . 37
Annex B (informative): Derivation of timings. 38
Annex C (informative): Example proforma for the declaration of modes of operation/use. 40
History. 43

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Terminal Equipment (TE)
Technical Committee of the European Telecommunications Standards Institute (ETSI). The text of this ETS
may be utilized, wholly or in part, for the establishment of NET 23.
This ETS contains the technical requirements for approval to Category II of 2400 bits per second duplex
modems standardized for use on the Public Switched Telephone Network (PSTN). Testing and approval to
Category II is applicable only at the request of the applicant. These requirements are based upon, and do
not conflict with, CCITT Recommendation V.22bis [7].
Additionally, requirements are included which relate to end-to-end inter-operability over PSTN connections.
These requirements are in excess of the CCITT Recommendations. A modem which complies with CCITT
Recommendation V.22bis [7] should always meet the requirements of this ETS which relate to parameters
specified in that CCITT Recommendation.
Clause 4 of this ETS references the requirements which are common to both Category I and Category II
modems. This is stated in Clause 4 of ETS 300 114 [2].
Clause 5 of this ETS contains Category II requirements specific to 2400 bits per second duplex modems.
In the case of certain functions common to a number of different types of modem (e.g. Auto-answering
sequence) reference is made to Clause 5 of ETS 300 114 [2] which contains the relevant requirements.

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1 Scope
This ETS specifies the technical characteristics to be met by modems seeking Category II approval for
duplex operation over the PSTN at 2400 bits per second. The modulation scheme specified is that
described in CCITT Recommendation V.22bis [7].
The term "modem" in the context of this ETS includes all physical implementation practices for voice band
modems, which are galvanically connected to the PSTN.
This ETS specifies four modes of operation each with five modes of use (see subclause 5.2).
This ETS also contains descriptions of the tests to be performed in order to confirm compliance with the
functional requirements contained herein. A general description of the test conditions and test requirements
is given in Annex A.
2 Normative references
This ETS 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 ETS
only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies.
[1] Draft prETS 300 001: "Attachments to the Public Switched Telephone Network
(PSTN); General requirements for equipment connected to an analogue
subscriber interface in the PSTN".
[2] ETS 300 114: 1990: "Attachments to the Public Switched Telephone Network
(PSTN); Basic attachment requirements for modems standardized for use on the
PSTN."
[3] CCITT Recommendation Q.144 (1984): "Specifications of Signalling System No
5: Line Signal Receiver".
[4] CCITT Recommendation S.33 (1984): "Standardization of an international text
for the measurement of the margin of start-stop machines using International
Alphabet No 5".
[5] CCITT Recommendation V.14 (1988): "Transmission of start-stop characters
over synchronous bearer channels".
[6] CCITT Recommendation V.22 (1984): "1200 bits per second duplex modem
standardized for use in the General Switched Telephone Network and on point-
to-point 2-wire leased telephone-type circuits".
[7] CCITT Recommendation V.22bis (1988): "2400 bits per second duplex modem
using the frequency division technique standardized for use on the General
Switched Telephone Network and on point-to-point 2-wire leased telephone-type
circuits".
[8] CCITT Recommendation V.25 (1984): "Automatic answering equipment and/or
parallel automatic calling equipment on the general switched telephone network
including procedures for disabling of echo control devices for both manually and
automatically established calls".
[9] CCITT Recommendation V.42 (1988): "Error correcting procedures for DCEs
using asynchronous-to-synchronous conversion".
[10] CCITT Recommendation V.52 (1984): "Characteristics of distortion and error-
rate measuring apparatus for data transmissiion.

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[11] CCITT Recommendation V.54 (1984): "Loop Test devices for modems".
3 Definitions and abbreviations
3.1 Definitions
For the purpose of this ETS the definitions of ETS 300 114 [2] apply, together with the following.
Answer mode: when calls are established with automatic facilities, a standard answer mode shall be used
by the modem at the answering station. This mode consists of conventional characteristics (e.g. use of
high channel carrier frequency or particular scrambler generating polynomial) complementary to those used
in the standard call mode by the modem at the calling station, in order to ensure proper connection and
inter-working.
If calls are established on the Public Switched Telephone Network (PSTN) by operators, or for leased
line operation, bilateral agreement on the use of call mode and answer mode shall be necessary.
Call mode: when calls are established with automatic facilities, a standard call mode shall be used by the
modem at the calling station. This mode consists of conventional characteristics (e.g. use of low channel
carrier frequency or particular scrambler generating polynomial) complementary to those used in the
standard answer mode by the modem at the answering station, in order to ensure proper connection and
inter-working.
If calls are established on the PSTN by operators, or for leased line operation, bilateral agreement on the
use of call mode and answer mode shall be necessary.
Data Terminal Equipment (DTE): is used to define the origin and destination of signals present at the
digital interface of a modem. This expression does not require that a "commercial data terminal" be
present to receive or generate such signals; a tester or any other suitable device may monitor or generate
such signals.
Initiation and Acknowledgement Signal (S1): comprises an unscrambled repetitive double dibit pattern
of '00' and '11' at 1200 bit/s.
Modem: a functional unit that modulates and demodulates signals in order to enable digital data to be
transmitted over analogue transmission facilities.
Modem Conformance Tester (MCT): this is essentially a modem to the same recommendation as the
modem under test, but the individual sub-systems within it are both accessible (e.g. provide test points and
permit functions to be enabled or disabled when required) and externally controllable (e.g. permit
sequences such as the start up procedure to be selectively repeated). The sub-systems within a
conformance tester may be constructed as discrete items of equipment, so as to permit their assembly
into varying configurations required to suit the tests (e.g. the asynchronous to synchronous converter may
be simply applied to a synchronous CCITT Recommendation V.22 [6] conformance tester to achieve an
asynchronous CCITT Recommendation V.22 [6] conformance tester).
As an interim measure, until the conformance tester is defined, its definition agreed to be appropriate by
ETSI, and such a tester is available, a modem used for reference may be used in its place. In the absence
of previous approval to Category II of the modem used for reference, in the relevant modes of
use/operation, the testing authority shall ensure that the modem used for reference complies with the
relevant ETS to the extent necessary for the performance of the test.
Modem used for reference: a modem used for some of the tests specified herein or in another modem
specific ETS. A modem used for reference may, at the discretion of the applicant, be provided by the
testing authority or by himself. It shall be designed:
- to meet the requirements of the same CCITT Recommendation(s) as the modem under test, to the
extent necessary for performing the tests;

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- to provide the functionalities for a modem used for reference that are specified in the relevant
testing Clauses; and
- to provide an interface which is accessible and of a type suitable for use in the tests (e.g. CCITT
Recommendation V.24).
Where the applicant has provided the modem used for reference and the test fails, the testing authority
may not be in a position to determine the precise reason for failure.
Modes of operation: modes specified in this modem specific ETS, that have an influence upon line signals
present at the PSTN interface.
Modes of use: modes specified in this modem specific ETS, that have an influence upon conditions
present at a digital interface e.g. a "conventional" CCITT Recommendation V.24 interface or a PC bus
interface in the case of an integral modem.
On-line state: the on-line state or condition is defined as an electrical condition into which, when
connected to the network, a modem is placed such that it draws enough current to be capable of activating
the exchange.
NOTE: Usually, a modem in on-line state is potentially capable of sending or receiving speech-
band information to or from the network.
Silence: signals which in the relevant frequency band have an in-band power level which is at least 30 dB
below the level of the transmitted signal at the point of measurement. This term is used to describe periods
where signals are not transmitted during the hand-shaking sequences.
3.2 Abbreviations
AMM Answer Mode Modem
CCITT Comité Consultatif International Télégraphique et Téléphonique
Cct Circuit
CEPT Conférence Européenne des Administrations des Postes et des
Télécommunications
CMM Call Mode Modem
DCE Data Circuit-Terminating Equipment
DTE Data Terminal Equipment
ETS European Telecommunication Standard
ETSI European Telecommunications Standards Institute
MCT Modem Conformance Tester
PSTN Public Switched Telephone Network
4 General requirements
4.1 References to other ETSs
The modem shall comply with ETS 300 114 [2], Clause 4.
NOTE: ETS 300 114 [2] in turn refers to Draft prETS 300 001 [1] for the majority, if not all, of
its requirements.
4.2 Information to be provided by the applicant
4.2.1 Information required for testing purposes
The applicant shall declare which tests are relevant to the modes of operation/use identified in this ETS
and are applicable to the equipment submitted for test.
Compliance is considered to have been accomplished by provision of the relevant information.

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NOTE : This could be accomplished by completion of forms such as those provided in Annex C
(informative).
4.2.2 Instructions for use
Instructions for use shall be made available with the apparatus. The instructions for use shall include :
a) the apparatus or types of apparatus to which the instructions apply;
b) any information specifically indicated in this ETS for inclusion in the "Instructions for use"; and
c) any national restrictions on the use of the apparatus.
Any additional information that has been included shall be disregarded unless it is the subject of another
ETS.
Compliance shall be checked by inspection.
5 Functional requirements specific to Category II modems
5.1 General requirements
To comply with the requirements of this ETS, it shall be necessary that the modem provide:
a) duplex mode of operation with continuous carrier, by means of the modulation scheme specified in
CCITT Recommendation V.22bis [7];
b) channel separation by frequency division;
c) means by which the channels may be selected either manually and/or automatically, where a
modem is capable of transmitting in either of the two channels;
d) provision of a guard tone of 1800 Hz ± 20 Hz, which a modem is to transmit while transmitting in the
high channel;
e) signalling rates of 2400 bit/s and 1200 bit/s.
NOTE 1: The general requirements described above are a subset of the CCITT
Recommendation V.22bis [7]. In the requirements which follow any deviations from the
strict interpretation of the Recommendation have been identified.
NOTE 2: In the following, references are made to interchange circuits between the modem and
the Data Terminal Equipment (DTE), as defined in CCITT Recommendation V.24.
However, not all modems provide an interface with such circuits. For these cases the
references to CCITT Recommendation V.24 type interchange circuits indicate
equivalent operation of a DTE and of a modem where this exists.
NOTE 3: To perform certain tests specified herein, it is desirable that it be possible to disable
the transmit scrambler of the modem.
5.2 Modes
It shall be possible to configure the modem to operate at 2400 bit/s and at 1200 bit/s in at least one of the
following modes of use for either the call mode or the answer mode or, optionally, both the call and answer
modes:
a) Asynchronous with 8 bits per character;
b) Asynchronous with 9 bits per character;

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c) Asynchronous with 10 bits per character;
d) Asynchronous with 11 bits per character;
e) Synchronous.
In the asynchronous (start-stop) modes of use, the modem shall accept a data stream from the DTE at a
nominal rate of 2400 bits per second and 1200 bits per second. The asynchronous data to be transmitted
shall be converted into a synchronous data stream in accordance with subclause 5.9 suitable for
transmission.
Demodulated data shall be decoded in accordance with subclause 5.5, then descrambled in accordance
with subclause 5.10, it shall then be passed for reconversion into an asynchronous data stream in
accordance with subclause 5.9.
In the synchronous modes of use, the modem shall accept synchronous data from the DTE. The data shall
then be scrambled in accordance with subclause 5.10 and passed to the modulator for encoding in
accordance with subclause 5.5.
Demodulated data shall be decoded in accordance with subclause 5.5, then descrambled in accordance
with subclause 5.10.
Optionally, the modem may also provide facilities to instigate:
a) a retrain procedure during data transmission if the modem detects a loss of equalization; and/or
b) a rate change in a remote modem and also to respond to a rate change request. This facility, when
provided, permits modems to alter their rate of operation from 2400 bit/s to 1200 bit/s, and vice
versa, without disconnection from the PSTN.
It shall be the applicant's responsibility to specify for which of these modes of o
...