ETSI ETS 300 117 ed.1 (1991-06)
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)
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)
T/TE 04-20 [AH]
Priključitve na javno komutirano telefonsko omrežje (PSTN) – Priključitvene zahteve kategorije II za dupleksne modeme za hitrosti 2400 b/s, standardizirane za uporabo v PSTN
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2003
3ULNOMXþLWYHQDMDYQRNRPXWLUDQRWHOHIRQVNRRPUHåMH 3671 ±3ULNOMXþLWYHQH
]DKWHYHNDWHJRULMH,,]DGXSOHNVQHPRGHPH]DKLWURVWLEVVWDQGDUGL]LUDQH]D
XSRUDERY3671
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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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ETS 300 117: June 1991
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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ETS 300 117: June 1991
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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ETS 300 117: June 1991
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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ETS 300 117: June 1991
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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ETS 300 117: June 1991
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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ETS 300 117: June 1991
[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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ETS 300 117: June 1991
- 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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ETS 300 117: June 1991
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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ETS 300 117: June 1991
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 operation/use testing for
conformance to this ETS is required.
5.3 Line signals
5.3.1 Carrier frequencies
The carrier frequencies shall be 1200 Hz ± 0,5 Hz for the low channel and 2400 Hz ± 1 Hz for the high
channel.
Compliance shall be checked by the method described in Annex A, Clause A.2.
5.3.2 Guard tone
5.3.2.1 Guard tone - call mode modem
When the modem is transmitting in the low channel, it shall not transmit the guard tone specified in
subclause 5.3.2.2.
Compliance shall be checked by the method described in Annex A, subclause A.3.1.
5.3.2.2 Guard tone - answer mode modem
When the modem is transmitting in the high channel, a guard tone at 1800 Hz ± 20 Hz shall be transmitted
simultaneously. The level of the guard tone shall be 6 dB ± 1 dB below the level of the data signal in the
high channel.
Optionally, facilities may be provided to disable the transmission of the guard tone of 1800 Hz. Since the
provision of the guard tone is mandatory, all tests in this ETS shall be carried out with guard tone present.
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ETS 300 117: June 1991
Compliance shall be checked by the method described in Annex A, subclause A.3.2.
The overall level of the guard tone and the data signal of a CCITT Recommendation V.22bis [7] modem
shall remain in compliance with the in-band spectral power limits for the network to which they are being
connected (see ETS 300 114 [2], Clause 4).
NOTE: The purpose of the guard tone is to inhibit the false operation of in-band signalling
systems such as in international networks (see CCITT Recommendation Q.144 [3]). It
is thought by some that a marginal performance advantage may be gained as a result
of the slightly higher transmit level possible when the guard tone is disabled and
therefore this option is permitted.
5.3.3 Transmitted spectrum
The national network specific spectral power limits are specified in ETS 300 114 [2], Clause 4.
NOTE: ETS 300 114 [2], Clause 4 in turn refers to Draft prETS 300 001 [1]. There are no
requirements in this ETS relating to the spectrum of signals presented to the PSTN
over and above those for PSTN access invoked by subclause 4.1.
5.4 Line signalling rates
The signalling rates transmitted to line shall be 2400 bit/s and 1200 bit/s ± 0,01%
Compliance shall be checked by the method described in Annex A, Clause A.4.
5.5 Encoding and decoding of data
The encoding and decoding of data shall be in accordance with CCITT Recommendation V.22bis [7],
Section 2.5.2 and Table 1/V.22bis.
Until a Modem Conformance Tester (MCT) is available, compliance shall be checked by inspection of the
applicant's declaration of conformance. When a MCT is available, compliance shall be checked by the
method described in Annex A, Clause A.5.
5.6 Threshold of the received line signal detector
The modem shall comply with the requirements of ETS 300 114 [2], subclause 5.4, when receiving a data
signal corresponding to scrambled binary 1 at 2400 bit/s and at 1200 bit/s in the respective receive
channel for the modem.
Compliance shall be checked by the method described in Annex A, Clause A.6.
5.7 Channel allocation
A Call Mode Modem (CMM) shall be capable of transmitting signals in the low channel and responding to
signals received in the high channel. An Answer Mode Modem (AMM) shall be capable of transmitting
signals in the high channel and responding to signals received in the low channel.
5.7.1 Channel selection
A modem which is capable of being configured as both a CMM and an AMM shall provide facilities for at
least one of the following techniques of channel selection:
a) manual selection of the channels using facilities provided on the modem;
b) selection of the channels by the DTE (equivalent: Cct 126 control);
c) automatic selection of the channels as described in subclause 5.7.2.
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ETS 300 117: June 1991
NOTE: Other means of channel selection may also be provided but verification of the correct
functioning of such facilities is not a requirement of this ETS.
For techniques a) and b), compliance shall be checked by the method described in Annex A, subclause
A.7.1.
5.7.2 Automatic channel selection
A modem providing this facility shall, in the absence of manual intervention or a contrary command e.g. via
a digital interface (e.g. an equivalent to control using Cct 126), be automatically configured as:
a) a CMM when exchanging data on-line to another compatible modem, and when the modem has
entered the on-line state other than in response to an incoming PSTN call;
b) an AMM when exchanging data on-line to another compatible modem, and when the modem has
entered the on-line state in response to an incoming PSTN call.
Compliance shall be checked by the method described in Annex A, subclause A.7.2.
5.8 Hand-shaking sequences
In the following sequences the signal described shall be sent contiguously unless the description indicates
that a period of silence be present.
5.8.1 Auto-calling and auto-answering procedures
5.8.1.1 Auto-calling - calling tone
This ETS does not require the provision of the calling tone defined in CCITT Recommendation V.25 [8].
5.8.1.2 Auto-calling - recognition of answering tone
For modems to be used for automatically originated calls, the modem, or its associated call establishment
equipment, shall comply with the requirements for answering tone detection given in ETS 300 114 [2],
subclause 5.2.1.
5.8.1.3 Auto-answering
For modems to be used for automatically answered calls, the modem, or its associated call answering
equipment, shall comply with the requirements for answering tone generation given in ETS 300 114 [2],
subclause 5.2.2.
5.8.2 Start-up procedures
Initially, the modem shall be indicating that:
a) it is not detecting a valid carrier signal (equivalent: Cct 109 OFF);
b) it is not ready to transmit data (equivalent: Cct 106 OFF).
NOTE: For a modem to indicate that it is ready to transmit data (equivalent: turning ON
Cct 106) requires that the DTE has indicated that it wishes to transmit data (equivalent:
turning ON Cct 105).
5.8.2.1 Call mode modem
After connection to line and when presented with contiguous unscrambled binary 1 at 1200 bit/s and guard
tone from an AMM, the CMM shall remain silent for a minimum of 591 ms. The CMM shall then transmit
Signal S1 (see Clause 3) for 100 ms ± 3 ms, followed by scrambled binary 1 at 1200 bit/s.
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The handshake sequence which follows depends upon whether the AMM is set to operate at 2400 bit/s or
at 1200 bit/s. This is described in subclauses 5.8.2.1.1 and 5.8.2.1.2.
5.8.2.1.1 AMM set to 2400 bit/s (CCITT Recommendation V.22bis [7])
The modem conformance tester (the AMM) shall respond by replacing the unscrambled binary 1 at 1200
bit/s with Signal S1 for 100 ms ± 3 ms followed by scrambled binary 1 at 1200 bit/s.
When a change from unscrambled binary 1 at 1200 bit/s to signal S1 occurs in the data received by the
CMM, it shall continue to transmit the scrambled binary 1 at 1200 bit/s for 600 ms ± 10 ms timed from the
end of receipt of Signal S1, followed by scrambled binary 1s at 2400 bit/s for 200 ms ± 10 ms.
At the end of this period, the CMM shall
a) give an indication to the DTE that the modem has detected a valid carrier signal (equivalent: turning
ON Cct 109);
b) give an indication to the DTE that the modem is now ready to transmit data (equivalent: turning ON
Cct 106); and
c) enter the data transmission phase.
For a CMM, condition a) should always occur before condition b) although the criteria for test is simply that
these indications are now ON.
Compliance shall be checked by the method described in Annex A, subclause A.8.1.1.1.
5.8.2.1.2 AMM set to 1200 bit/s (CCITT Recommendation V.22 [6] or V.22bis [7])
The modem conformance tester (the AMM) shall respond by replacing the unscrambled binary 1 with
scrambled binary 1 at 1200 bit/s.
When a change from unscrambled binary 1 to scrambled binary 1 at 1200 bit/s occurs in the data received
by the CMM, it shall continue to transmit the scrambled binary 1 at 1200 bit/s for 1035 ms ± 50 ms.
At the end of this period, the CMM shall
a) give an indication to the DTE that the modem has detected a valid carrier signal (equivalent: turning
ON Cct 109);
b) give an indication to the DTE that the modem is now ready to transmit data (equivalent: turning ON
Cct 106); and
c) enter the data transmission phase.
For a CMM, condition a) should always occur before condition b) although the criteria for test is simply that
these indications are now ON.
Compliance shall be checked by the method described in Annex A, subclause A.8.1.1.2.
5.8.2.2 Answer mode modem
On completion of the CCITT Recommendation V.25 [9] auto-answering sequence or, when manually
answered, on connection to line, the AMM shall transmit unscrambled binary 1 at 1200 bit/s and guard
tone.
The handshake sequence which follows this depends upon whether the CMM is set to operate at 2400
bit/s or at 1200 bit/s, as discribed in subclauses 5.8.2.2.1 and 5.8.2.2.2.
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ETS 300 117: June 1991
5.8.2.2.1 CMM set to 2400 bit/s (CCITT Recommendation V.22bis [7])
The modem conformance tester (the CMM) shall respond by transmitting Signal S1 for 100 ms ± 3 ms
followed by scrambled binary 1 at 1200 bit/s
When a change from Signal S1 to scrambled binary 1 at 1200 bit/s occurs in the data received by the
AMM, it shall transmit signal S1 for 100 ms ± 3 ms followed by scrambled binary 1 at 1200 bit/s such that
the total period for signal S1 and this scrambled binary 1 is 600 ms ± 10 ms. This shall be followed by a
scrambled binary 1 signal at 2400 bit/s for 200 ms ± 10 ms.
The modem conformance tester shall now also be transmitting scrambled binary 1 at 2400 bit/s. At the end
of this period, the CMM shall:
a) give an indication to the DTE that the modem has detected a valid carrier signal (equivalent: turning
ON Cct 109);
b) give an indication to the DTE that the modem is now ready to transmit data (equivalent: turning ON
Cct 106); and
c) enter the data transmission phase.
For an AMM, conditions a) and b) should occur almost simultaneously. The order is therefore of no
importance.
NOTE: In the event that the rate change option has been established, the AMM may delay
transmission of the Signal S1 by more than 32 dibit duration after receipt of Signal S1
from the CMM.
Compliance shall be checked by the method described in Annex A, subclause A.8.1.2.1.
5.8.2.2.2 CMM set to 1200 bit/s
The modem conformance tester (the CMM) shall respond by transmitting scrambled binary 1 at 1200 bit/s.
When a change from silence to scrambled binary 1 at 1200 bit/s occurs in the data received by the AMM,
it shall continue to transmit unscrambled binary 1 at 1200 bit/s for a further 270 ms ± 40 ms, followed by
scrambled binary 1 at 1200 bit/s for 765 ms ± 10 ms.
At the end of this period, the CMM shall:
a) give an indication to the DTE that the modem has detected a valid carrier signal (equivalent: turning
ON Cct 109);
b) give an indication to the DTE that the modem is now ready to transmit data (equivalent: turning ON
Cct 106); and
c) enter the data transmission phase.
For an AMM, conditions a) and b) should occur almost simultaneously. The order is therefore of no
importance.
NOTE: In the event that the rate change option has been established, the AMM may delay
transmission of the Signal S1 by more than 32 dibit duration after receipt of Signal S1
from the CMM.
Compliance shall be checked by the method described in Annex A, subclause A.8.1.2.2.
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ETS 300 117: June 1991
5.8.3 Retrain sequence (2400 bit/s operation)
The requirements of this clause apply to modems for which the applicant has requested testing of this
facility for conformance to this ETS.
5.8.3.1 Initiating signal
The applicant shall indicate a method by which the modem may be caused to initiate a retrain.
Using the method described by the applicant, while the modem is transmitting at 2400 bit/s, it is caused to
initiate a retrain. The modem shall, give an indication to the DTE that the modem is not ready to transmit
data (equivalent: turning OFF Cct 106), and transmit signal S1 (see Clause 3) for 100 ms ± 3 ms. This
shall be followed by scrambled binary 1 at 1200 bit/s for a minimum period of 687 ms which shall be
followed, in turn, by scrambled binary 1 at 2400 bit/s for 200 ms ± 10 ms.
At the end of this period, the modem shall re-enter the data transfer phase at 2400 bit/s and give an
indication to the DTE that the modem is now ready to transmit data (equivalent: turning ON Cct 106).
Compliance shall be checked by the method described in Annex A, subclause A.8.2.1.
5.8.3.2 Response signal
When a change from scrambled data at 2400 bit/s to signal S1 occurs in the data received by the modem,
the modem shall give an indication to the DTE that the modem is not ready to transmit data (equivalent:
turning OFF Cct 106), and transmit signal S1 for 100 ms ± 3 ms. This shall be followed by scrambled
binary 1 at 1200 bit/s. The total time for which signal S1 and the subsequent scrambled binary 1 signal are
transmitted shall be 600 ms ± 10 ms. The modem shall replace the scrambled binary 1 at 1200 bit/s by
scrambled binary 1 at 2400 bit/s for 200 ms ± 10 ms.
At the end of this period, the modem shall re-enter the data transfer phase at 2400 bit/s and give an
indication to the DTE that the modem is now ready to transmit data (equivalent: turning ON Cct 106).
NOTE: In the event that the rate change option has been established, the modem may delay
transmission of the Signal S1 by more than 32 dibit durations after receipt of Signal S1
from the modem conformance tester.
Compliance shall be checked by the method described in Annex A, subclause A.8.2.2.
5.8.4 Rate change request
NOTE: The following clauses relate to an optional feature published in CCITT Recommendation
V.22bis [7]. This enables a V.22bis modem to signal a rate change request in the data
channel to a remote V.22bis modem.
In order for this facility to conform to the requirements of this ETS, where a modem provides the facility to
signal from one V.22bis modem a rate change request either from 2400 bit/s to 1200 bit/s or vice versa to
a remote V.22bis modem by means of the temporary cessation of transmission in the data channel of
scrambled data and by its substitution by the transmission of special symbols, or to act upon such a
request, the operation of that facility shall be in accordance with the requirements of subclauses 5.8.4.1
and 5.8.4.2.
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