ETSI ETS 300 116 ed.2 (1996-05)

SLOVENSKI STANDARD
01-december-2003
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XSRUDERY3671
Public Switched Telephone Network (PSTN); Category II specification for 1 200 bits per
second duplex modems standardized for use on the PSTN
Ta slovenski standard je istoveten z: ETS 300 116 Edition 2
ICS:
33.040.35 Telefonska omrežja Telephone networks
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 116
TELECOMMUNICATION May 1996
STANDARD Second Edition
Source:ETSI TC-TE Reference:RE/TE-05047
ICS: 33.020
modems, PSTN, testing
Key words:
Public Switched Telephone Network (PSTN);
Category II specification for 1 200 bits per
second duplex modems standardized for use on the PSTN
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 1996. All rights reserved.

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ETS 300 116: May 1996
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 300 116: May 1996
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions .8
3.2 Abbreviations .8
4 General requirements .8
4.1 References to other ETSs .8
4.2 Information to be provided by the applicant.8
4.2.1 Information required for testing purposes .8
4.2.2 Instructions for use.9
5 Functional requirements specific to category II modems.9
5.1 General requirements .9
5.2 Modes .10
5.3 Line signals.10
5.3.1 Carrier frequencies.10
5.3.2 Guard tone .11
5.3.2.1 Guard tone - call mode modem.11
5.3.2.2 Guard tone - answer mode modem.11
5.3.3 Transmitted spectrum .11
5.4 Line signalling rates .11
5.5 Encoding and decoding of data .11
5.6 Threshold of received line signal detection.12
5.7 Channel allocation .12
5.7.1 Channel selection.12
5.7.2 Automatic channel selection.12
5.8 Hand-shaking sequences .12
5.8.1 Auto-calling and auto-answering procedures.12
5.8.1.1 Auto-calling - calling tone.12
5.8.1.2 Auto-calling - recognition of answering tone.12
5.8.1.3 Auto-answering.13
5.8.2 Start-up procedures.13
5.8.2.1 Call Mode Modem.13
5.8.2.2 Answer Mode Modem.13
5.9 Transmission of start-stop characters .14
5.10 Scrambler and descrambler.14
5.11 Test loop 2 .14
5.11.1 Instigation of a remote loop 2.15
5.11.2 Termination of a remote loop 2 .15
5.12 Receiver performance .15
Annex A (normative): Testing methods.16
A.1 General testing conditions.16
A.1.1 General notes .16
A.1.2 Proposed order for performing the tests.16
A.1.3 Limitation of number of tests.17
A.1.3.1 Introduction.17
A.1.3.2 General rules.17
A.1.3.3 Specific rules.18

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ETS 300 116: May 1996
A.2 Test for subclause 5.3.1 (carrier frequencies). 18
A.2.1 Test for subclause 5.3.1 using the MCT . 18
A.2.2 Test for modems where the scrambler can be inhibited . 18
A.2.3 Tests for modems where test points are accessible. 19
A.2.4 Test for modems where neither subclause A.2.2 nor subclause A.2.3 applies . 19
A.3 Test for subclause 5.3.2 (guard tone). 19
A.3.1 Test for subclause 5.3.2.1 (guard tone, call mode modem) . 19
A.3.2 Test for subclause 5.3.2.2 (guard tone, answer mode modem) . 19
A.4 Test for subclause 5.4 (line signalling rates) . 20
A.5 Test for subclause 5.5 (encoding and decoding of data). 20
A.6 Test for subclause 5.6 (threshold of received line signal detection). 20
A.7 Test for subclause 5.7 (channel allocation). 20
A.7.1 Test for subclause 5.7.1 (general) . 21
A.7.2 Test for subclause 5.7.2 (automatic channel selection). 21
A.8 Test for subclause 5.8 (hand-shaking sequences). 21
A.8.1 Call mode modem (CMM). 21
A.8.2 Answer Mode Modem (AMM) . 22
A.9 Test for subclause 5.10 (scrambler and descrambler). 23
A.9.1 Test for modems which can be operated in the synchronous mode of use. 23
A.9.2 Test for modems which can only be operated in a asynchronous mode of use . 23
A.10 Test for subclause 5.11 (test loop 2) . 24
A.10.1 Instigation of remote test loop 2 . 24
A.10.1.1 Transmission of the test loop initiation signal (controlling modem under
test). 24
A.10.1.2 Response to the test loop initiation signal (controlled modem under test) . 24
A.10.2 Deactivation of remote test loop 2. 25
A.10.2.1 Transmission of the deactivation signal(controlling modem under test). 25
A.10.2.2 Response to the deactivation signal (controlled modem under test). 25
Annex B (normative): Derivation of timings . 26
Annex C (informative): Example proforma for the declaration of modes of operation/use. 27
Annex D (informative): Bibliography . 29
History. 30

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ETS 300 116: May 1996
Foreword
This second edition European Telecommunication Standard (ETS) has been produced by the Terminal
Equipment (TE) Technical Committee of the European Telecommunications Standards Institute (ETSI).
The objective of this specification, the application of which is entirely voluntary, is to provide the users with
an added degree of assurance that modems in compliance with this specification can interwork with each
other, under most network conditions.
This ETS contains the technical characteristics required for end-to-end interworking over the Public
Switched Telephone Network (PSTN) for 1 200 bits per second duplex modems standardized for use over
the PSTN.
These requirements are based on, and do not conflict with, CCITT Recommendation V.22 [1]. Additional
requirements are included relating to end-to-end inter-operability over PSTN connections. Such
requirements are in excess of the CCITT/ITU-T Recommendations.
Except where otherwise indicated, a modem which complies with CCITT Recommendation V.22 [1]
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, which are contained in clause 4 of final draft prETS 300 114 [2]. The definition of Category I and
Category II modems can be found in the foreword of final draft prETS 300 114 [2].
Clause 5 of this ETS contains Category II requirements specific to 1 200 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 final draft prETS 300 114 [2] which contains the relevant
requirements.
Transposition dates
Date of adoption of this ETS: 26 April 1996
Date of latest announcement of this ETS (doa): 31 August 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 29 February 1997
Date of withdrawal of any conflicting National Standard (dow): 29 February 1997

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ETS 300 116: May 1996
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ETS 300 116: May 1996
1 Scope
This ETS contains the technical characteristics required for end-to-end interworking over the Public
Switched Telephone Network (PSTN) of 1 200 bits per second (bit/s) duplex modems standardized for
use over the in accordance with CCITT Recommendation V.22 [1].
NOTE: CCITT Recommendation V.22 [1] also describes a method of transmitting data at
600 bit/s. This ETS specifies the characteristics to be met by such modems and, if
requested by the applicant, this feature can also be tested against the specifications.
The term "modem" in the context of this ETS includes all physical implementation practices for a voice
band modem which is conductively connected to the PSTN.
This ETS specifies four modes of operation each with up to 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 (normative).
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] CCITT Recommendation V.22 (1984): "1 200 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".
[2] Final draft prETS 300 114 (1996): "Public Switched Telephone Network (PSTN);
Basic Category I and Category II specifications for modems standardized for
use on the PSTN".
[3] ETS 300 001: "Attachments to the Public Switched Telephone Network (PSTN);
General technical requirements for equipment connected to an analogue
subscriber interface in the PSTN".
[4] 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".
[5] 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".
[6] CCITT Recommendation V.52 (1984): "Characteristics of distortion and error-
rate measuring apparatus for data transmission".

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ETS 300 116: May 1996
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the definitions of final draft prETS 300 114 [2] apply, together with the
following:
Modem Conformance Tester (MCT): 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 [1] conformance tester to achieve an
asynchronous V.22 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 case
that the modem used for reference has not been shown to conform to the ETS in the relevant modes of
operation/use, the testing authority ensures that the modem used for reference complies with the relevant
ETS to the extent necessary for the performance of the test.
silence: Periods during the hand-shaking sequences where signals are not transmitted.
The period of silence is measured using the start and finish criteria defined below. The levels refer to
signals which in the relevant frequency band have an in-band power level and are expressed with respect
to the normal transmitted signal level of the modem under test recorded at the point of observation.
start of the period of silence: The instant at which the transmitted signal level drops below a level that is
6 dB below the normal transmit level.
end of period of silence: The instant the transmitted signal rises above a level that is 6 dB below the
normal transmit level. During the period of silence at least one instant is observed where the signal level is
at least 30 dB below the normal transmit level.
3.2 Abbreviations
For the purposes of this ETS, the abbreviations given in final draft prETS 300 114 [2] apply.
4 General requirements
4.1 References to other ETSs
The modem shall comply with final draft prETS 300 114 [2], clause 4.
NOTE: Final draft prETS 300 114 [2] in turn refers to ETS 300 001 [3] 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 for which of the modes of operation/use identified in this ETS, the modem is
supposed to undergo tests.
Compliance shall be considered to have been accomplished by provision of the relevant information.
NOTE: This could be accomplished by completion of forms such as those provided in
annex C.
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ETS 300 116: May 1996
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, the modem shall provide:
- duplex mode of operation with continuous carrier, by means of the modulation scheme specified in
CCITT Recommendation V.22 [1];
- channel separation by frequency division;
- 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;
- provision of a guard tone of 1 800 Hz ± 20 Hz, which a modem is to transmit while transmitting in
the high channel;
- signalling rates of 1 200 bit/s and, optionally, 600 bit/s;
- the interchange circuits (or equivalent) that are required to change state after an identifiable event
or point in time, shall have changed state within a maximum of 3 seconds of that event, unless
otherwise specified (see note 4).
NOTE 1: The general requirements described above are a subset of CCITT Recommendation
V.22 [1]. 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 interchange circuits. For
these cases the references to CCITT Recommendation V.24 type interchange circuits
indicate equivalent functionality of a DTE and a modem.
NOTE 3: To perform certain tests specified herein, it is desirable that it be possible to disable
the transmit scrambler of the modem.
NOTE 4: This requirement is in addition to CCITT Recommendation V.22 [1].

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ETS 300 116: May 1996
5.2 Modes
It shall be possible to configure the modem to operate in at least one of the following modes of operation:
- 1 200 bit/s call mode;
- 1 200 bit/s answer mode;
and, optionally, in one or both of the following modes of operation:
- 600 bit/s call mode;
- 600 bit/s answer mode.
For each of the modes of operation at least one of the following modes of use shall be provided:
a) asynchronous with 8 bits per character;
b) asynchronous with 9 bits per character;
c) asynchronous with 10 bits per character;
d) asynchronous with 11 bits per character;
e) synchronous.
NOTE: It is acceptable for the same mode of use to be provided for each of the modes of
operation selected.
In the asynchronous (start-stop) modes of operation, the modem shall accept a data stream from the DTE
at a nominal rate of 1 200 bits per second or, optionally, 600 bits per second. The asynchronous data to
be transmitted shall, in accordance with subclause 5.9, be converted into a synchronous data stream
suitable for transmission.
Demodulated data shall be decoded in accordance with subclause 5.5, then descrambled in accordance
with subclause 5.10 and it shall then be passed for re-conversion into an asynchronous data stream in
accordance with subclause 5.9.
In the synchronous mode of operation, 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.
It shall be the applicant's responsibility to specify for which of these modes of operation/use the modem is
supposed to undergo tests.
5.3 Line signals
5.3.1 Carrier frequencies
The carrier frequencies shall be 1 200 Hz ± 0,5 Hz for the low channel and 2 400 Hz ± 1 Hz for the high
channel.
Compliance shall be checked by the method described in annex A, clause A.2.

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ETS 300 116: May 1996
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 1 800 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 1 800 Hz. Since the
provision of the guard tone is mandatory, all tests in this ETS shall be carried out with guard tone present.
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.22 [1] modem shall
remain in compliance with the in-band spectral power limits for the network to which they are being
connected (see final draft prETS 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). 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 final draft prETS 300 114 [2], clause 4.
NOTE: Final draft prETS 300 114 [2], clause 4 in turn refers to ETS 300 001 [3]. 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 1 200 bit/s ± 0,01 % and, if requested by the applicant,
600 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.22 [1],
section 2.5.2 and table 1/V.22.
Until a Modem Conformance Tester (MCT) is available, compliance shall be checked by inspection of the
applicant's declaration of conformance. When an MCT is available, compliance shall be checked by the
method described in annex A, clause A.5.

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ETS 300 116: May 1996
5.6 Threshold of received line signal detection
The modem shall comply with the requirements of final draft prETS 300 114 [2], subclause 5.4, when
receiving a data signal corresponding to scrambled binary 1 at 1 200 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.
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 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 continuously 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 shall not require the provision of the calling tone defined in CCITT Recommendation V.25 [4].
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 final draft
prETS 300 114 [2], subclause 5.2.1.

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ETS 300 116: May 1996
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 final draft
prETS 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 unscrambled binary 1 and the guard tone from the
remote modem (AMM), the CMM shall remain silent for a minimum of 551 ms. The modem shall then
transmit scrambled binary 1.
NOTE: The value of 551 ms is derived from CCITT Recommendation V.22 [1] and is not the
same as the value for CCITT Recommendation V.22bis. (see annex B).
When a change from unscrambled binary 1 to scrambled binary 1 occurs in the data received by the
CMM, it shall continue to transmit the scrambled binary 1 for a further period of 1 035 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);
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.
5.8.2.2 Answer Mode Modem
On completion of the CCITT Recommendation V.25 [4] auto-answering sequence or, when manually
answered, on connection to line, the AMM shall transmit unscrambled binary 1 at 1 200 bit/s and the
guard tone. When a change from silence to scrambled binary 1 at 1 200 bit/s occurs in the line signal
received by the AMM, it shall continue to transmit unscrambled binary 1 at 1 200 bit/s and the guard tone
for a further 270 ms ± 40 ms followed by scrambled binary 1 at 1 200 bit/s and the guard tone for 765 ms
± 10 ms.
At the end of this period, the AMM 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);
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ETS 300 116: May 1996
c) enter the data transmission phase.
For an AMM, conditions a) and b) should occur almost simultaneously. The order is therefore of no
importance.
Compliance shall be checked by the method described in annex A, subclause A.8.2.
5.9 Transmission of start-stop characters
If the modem is capable of transmitting start-stop characters without error correction, speed conversion or
flow control, it shall provide at least one of the following modes of use at 1 200 bit/s and, where requested
by the applicant, at 600 bit/s:
a) asynchronous with 8 bits per character;
b) asynchronous with 9 bits per character;
c) asynchronous with 10 bits per character;
d) asynchronous with 11 bits per character.
The asynchronous-to-synchronous conversion shall be in accordance with final draft prETS 300 114 [2],
subclause 5.5.
NOTE: The tests for compliance with the above requirements are described in final draft
prETS 300 114 [2], annex B, clause B.5.
5.10 Scrambler and descrambler
A self synchronizing scrambler and a self synchronizing descrambler, as specified in CCITT
Recommendation V.22 [1], subclauses 5.1 and 5.2, shall be provided in the transmitting part and the
receiving part, respectively, of the modem.
This implies that:
- the scrambler shall include circuitry to detect a sequence of 64 consecutive binary 1 s at its output
and, if detected, invert the next bit input to the scrambler;
- the descrambler may or may not include a circuitry to detect sequences of 64 consecutive binary 1s
at its input and, when detected, to invert the next bit output from the descrambler. Where such a
circuitry is included, it shall not begin operating prior to the initial hand-shaking sequence being
completed. Furthermore, where this circuitry is included, the detection of the test loop 2 initiating
signal of unscrambled binary 1s (see subclause 5.11.1, b)) shall be performed before the inversion
described above can take place.
Compliance shall be checked by the method described in annex A, clause A.9.
5.11 Test loop 2
The modem shall provide facilities for the implementation and the remote control of test loop 2. The
description of test loop 2 may be found in final draft prETS 300 114 [2], subclause 5.3.2.
NOTE: The inter-DCE signalling for control of test loop 2 as specified in CCITT
Recommendation V.54 has not been adopted for modems according to CCITT
Recommendation V.22 [1]. Instead a different procedure has been defined in that
Recommendation.
In the following, the sequences for the remote control of test loop 2 are defined irrespective of the line
signalling rate (600 bit/s or 1 200 bit/s).

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ETS 300 116: May 1996
5.11.1 Instigation of a remote loop 2
a) controlling modem
The modem which is instructed, either manually or by the DTE (equivalent: turning ON CcT 140), to
instigate a remote loop 2, shall transmit an initiation signal of unscrambled binary 1.
When the modem is presented with scrambled reversals it shall detect them and, after not less than
231 ms, and not more than 308 ms transmit scrambled binary 1.
When presented with scrambled binary 1, the modem shall indicate to the user or to the DTE (equivalent:
turning ON CcT 142) that the modem is in a test mode.
Compliance shall be checked by the method described in annex A, subclause A.10.1.1.
b) controlled modem
When the modem is presented with the initiation signal of unscrambled binary 1, transmitted by the
remote modem, for not less than 154 ms and not more than 231 ms, it shall detect them and transmit
scrambled reversals.
When presented with scrambled binary 1, the modem shall activate loop 2 and indicate to the user or to
the DTE (equivalent: turning ON CcT 142) that the modem is in a test mode.
Compliance shall be checked by the method described in annex A, subclause A.10.1.2.
5.11.2 Termination of a remote loop 2
a) controlling modem
When the modem from which a remote loop 2 had been instigated is instructed to terminate that loop
(equivalent: turning OFF CcT 140, where the remote loop 2 instigation was controlled by the DTE), it shall
suppress the line signal for 77 ms ± 10 ms after which data transmission shall be restored. The modem
shall indicate to the user or to DTE (equivalent: turning OFF CcT 142) that the modem is no longer in a
test mode.
Compliance shall be checked by the method described in annex A, subclause A.10.2.1.
b) controlled modem
When the modem inside which a loop 2 was remotely instigated is presented with a loss of line signal for
17 ms ± 7 ms followed by the reappearance of the signal, it shall de-activate loop 2 and restore normal
operation within 172 ms ± 57 ms, after which data transmission shall be restored. The modem shall
indicate to the user or to DTE (equivalent: turning OFF CcT 142) that the modem is no longer in a test
mode.
Compliance shall be checked by the method described in annex A, subclause A.10.2.2.
5.12 Receiver performance
When tested as described in final draft prETS 300 114 [2], subclause 5.6, the modem shall accumulate
not less than 75 % error free seconds during each of the performance testing periods.
NOTE 1: Since CCITT Recommendation V.22 [1] does not define performance criteria, the
requirements of this clause are additional to those of the CCITT Recommendation.
NOTE 2: The figure of 75 % is a provisional value, and based on reasoned estimations.

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Annex A (normative): Testing methods
A.1 General testing conditions
A.1.1 General notes
The general conditions for test shall apply, as described in final draft prETS 300 114 [2], annex B.
For the testing of the modem it shall generally be necessary to simulate the PSTN in the test set-up in
order for the modem under test and the MCT to remain in an on-line state. Unless otherwise indicated,
Test Line 3 (see final draft prETS 300 114 [2], annex C, clause C.5) shall be used to connect the modem
under test and the MCT.
The following information is given to aid the testing authority in determining the signals present on the line.
Unscrambled binary 1 at 1 200 bit/s is characterized by tones at 1 050 Hz and 1 650 Hz for the low
channel; and 2 250 Hz and 2 850 Hz for the high channel.
Whatever the binary input, scrambled binary signals are characterized by a general distribution of signal
power throughout the frequency band allocated to the particular mode (i.e. 650 Hz to 1 750 Hz for call
mode and 1 850 Hz to 2 950 Hz for answer mode). Therefore, the binary content of the transmitted data
signal cannot be determined without demodulation.
Where it is required to confirm that the data transfer phase has been established, a single message shall
be transmitted in each direction. There shall be no need to specifically check the text or data for errors
since all Category II modems are subjected to a performance check. The test message shall be:
- for asynchronous modems, " THE QUICK BROWN FOX." text in the international alphabet
N° 5 (IA5), according to CCITT Recommendation S.33 [5];
NOTE 1: Alternatively, the French version of the test text ("VOYEZ LE BRICK GEANT."), as
specified in CCITT Recommendation S.33 [5], may be used.
NOTE 2: Either the 64-character set version or the 95-character set version of the test texts, as
specified in CCITT Recommendation S.33 [5], may be used.
- for synchronous modems, approx 1 022 bits of pseudo-random data.
A.1.2 Proposed order for performing the tests
Except where otherwise stated, tests may be carried out in any order. The order of tests shall be at the
discretion of the testing authority.
The following proposal should therefore only be taken as a guideline:
NOTE: The following presentation is used for the designation of entries summarized
hereinafter:
Keyword/clause/subclause where the requirement is specified/clause where the test is specified (or other
means of conformance check).
1) Carrier frequencies/subclause 5.3.1/clause A.2;
2) Encoding and decoding of data/subclause 5.5/Applicant's declaration of conformance;
3) Auto answering sequence/subclause 5.8.1 (final draft prETS 300 114 [2], subclauses 5.2.1 and
5.2.2);
4) Start-up procedures/subclauses 5.8.2.1 and 5.8.2.2/subclauses A.8.1 and A.8.2;
5) Transmitted spectrum/subclause 5.3.3/final draft prETS 300 114 [2], clause 4; ETS 300 001 [3];

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ETS 300 116: May 1996
6) Channel allocation/subclauses 5.7.1 and 5.7.2/subclauses A.7.1 and A.7.2;
7) Line signalling rates/subclause 5.4/clause A.4;
8) Guard tone, call mode modem/subclause 5.3.2.1/subclause A.3.1;
9) Guard tone, answer mode modem/subclause 5.3.2.2/subclause A.3.2;
10) Threshold of received line signal detector (subclause 5.6; final draft prETS 300 114 [2],
subclause 5.4) clause A.6;
11) Scrambler and descrambler/subclause 5.10/clause A.9;
12) Asynchronous to synchronous converter/subclause 5.9 (final draft prETS 300 114 [2], clause B.5);
13) Instigation to a remote test loop 2/subclause 5.11.1 a)/subclause A.10.1.1;
14) Termination of a remote test loop 2/subclause 5.11.2 a)/subclause A.10.2.1;
15) Response to an activate test loop 2 command/subclause 5.11.1 b)/subclause A.10.1.2;
16) Response to a terminate test loop 2 command/subclause 5.11.2 b)/subclause A.10.2.2;
17) General requirements/subclause 5.1/Results of the relevant tests specified above;
18) Modes/subclause 5.2/Results of the relevant tests specified above;
19) Receiver performance/subclause 5.12 (final draft prETS 300 114 [2], subclauses B.6.4.2 and
B.6.4.3).
A.1.3 Limitation of number of tests
A.1.3.1 Introduction
Four modes of operation are described, each of which may have up to five modes of use.
The requirements as stated in this ETS are valid for all 20 possible modes. However, it is clear that the
performance of all the tests in all the possible modes is both unnecessary and undesirable.
The following subclauses of A.1.3 define the combinations of tests which shall be performed in order to
test conformity with this ETS.
In the remaining subclauses of A.1.3, the words "modes of operation" and "modes of use" refer only to
those modes for which the applicant has requested Category II conformance testing.
A.1.3.2 General rules
For each mode of operation, only one mode of use shall be tested. Where available, this shall be the
synchronous mode. Where tests are performed in the asynchronous mode one character length shall be
chosen using the following rule: the first choice is 10 bits/character, then 11 bits/character, then
9 bits/character and, finally, 8 bits/character.

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ETS 300 116: May 1996
A.1.3.3 Specific rules
After selection using the general rules given in subclause A.1.3.2, the following specific rules shall be
applied:
a) the following tests shall be performed, where relevant, for all modes of operation:
- carrier frequencies (requirement subclause 5.3.1 - test clause A.2);
- guard tone (requirement subclause 5.3.2 - test clause A.3);
- performance (requirement subclause 5.12).
b) The following tests shall be performed in both the call and answer modes of operation, where
relevant, at the highest available data signalling rate for the mode being tested:
- auto-call and auto-answer (requirement subclause 5.8.1 - test clause A.8);
- channel allocation (requirement subclause 5.7 - test clause A.7);
- threshold of received line signal detector (subclause 5.6 - test clause A.6).
c) The following tests shall be performed for one 1 200 bit/s mode of operation and, where relevant,
for one 600 bit/s mode of operation. Where the tests are to be performed at differing data signalling
rates, where possible one test shall be performed in the call mode of operation and the other in the
answer mode of operation:
- data signalling rates (requirement subclause 5.4 - test clause A.4);
- encoding and decoding (requirement subclause 5.5 - test clause A.5).
d) The following tests shall be performed for one 1 200 bit/s mode of operation:
- transmission of start/stop characters (requirement subclause 5.9);
-
...