SIST ETS 300 116 E1:2003

SLOVENSKI STANDARD
01-december-2003
3ULNOMXþLWYHQDMDYQRNRPXWLUDQRWHOHIRQVNRRPUHåMH3671±3ULNOMXþLWYHQH
]DKWHYHNDWHJRULMH,,]DGXSOHNVQHPRGHPH]DKLWURVWLEVVWDQGDUGL]LUDQH]D
XSRUDERY3671
Attachments to the Public Switched Telephone Network (PSTN); Category II attachment
requirements for 1200 bits per second duplex modems standardized for use on the
PSTN (Candidate NET 22)
Ta slovenski standard je istoveten z: ETS 300 116 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 300 116
TELECOMMUNICATION June 1991
STANDARD
Source: ETSI TC-TE Reference: T/TE 04-19
ICS: 33.020, 33.040.40
PSTN, 1200 bits/second duplex modems
Key words:
Attachments to the Public Switched Telephone Network (PSTN)
Category II attachment requirements for 1200 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 22)
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

Page 2
ETS 300 116: 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.

Page 3
ETS 300 116: June 1991
Contents
Foreword.5
1 Scope .7
2 Normative references .7
3 Definitions and abbreviations.8
3.1 Definitions and abbreviations.8
3.2 Abbreviations.9
4 General requirements .9
4.1 References to other ETSs .9
4.2 Information to be provided by the applicant .9
4.2.1 Information required for testing purposes .9
4.2.2 Instructions for use.10
5 Functional requirements specific to category II modems. 10
5.1 General requirements.10
5.2 Modes.10
5.3 Line signals.11
5.3.1 Carrier frequencies.11
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.12
5.4 Line signalling rates.12
5.5 Encoding and decoding of data .12
5.6 Threshold of received line signal detection.12
5.7 Channel allocation .12
5.7.1 Channel selection .13
5.7.2 Automatic channel selection .13
5.8 Hand-shaking sequences .13
5.8.1 Auto-calling and auto-answering procedures.13
5.8.1.1 Auto-calling - calling tone.13
5.8.1.2 Auto-calling - recognition of answering tone .13
5.8.1.3 Auto-answering .13
5.8.2 Start-up procedures . 14
5.8.2.1 Call mode modem.14
5.8.2.2 Answer mode modem .14
5.9 Transmission of start-stop characters.15
5.10 Scrambler and descrambler. 15
5.11 Test loop 2 .15
5.11.1 Instigation of a remote loop 2.16
5.11.2 Termination of a remote loop 2.16
5.12 Receiver performance .16
Annex A (normative): Testing methods .17
A.1 General testing conditions.17
A.1.1 General notes.17
A.1.2 Proposed order for performing the tests .17
A.1.3 Limitation of number of tests .18
A.1.3.1 Introduction. 18
A.1.3.2 General rules . 18

Page 4
ETS 300 116: June 1991
A.1.3.3 Specific Rules .19
A.2 Test for subclause 5.3.1 (carrier frequencies).19
A.2.1 Test for subclause 5.3.1 using the MCT.19
A.2.2 Test for modems where the scrambler can be inhibited.19
A.2.3 Tests for modems where test points are accessible.20
A.2.4 Test for modems where neither A.2.2 nor A.2.3 applies .20
A.3 Test for subclause 5.3.2 (guard tone) .20
A.3.1 Test for subclause 5.3.2.1 (guard tone, call mode modem).20
A.3.2 Test for subclause 5.3.2.2 (guard tone, answer mode modem).20
A.4 Test for subclause 5.4 (line signalling rates) .20
A.5 Test for subclause 5.5 (encoding and decoding of data) .21
A.6 Test for subclause 5.6 (threshold of received line signal detection).21
A.7 Test for subclause 5.7 (channel allocation) .21
A.7.1 Test for subclause 5.7.1 (general) .22
A.7.2 Test for subclause 5.7.2 (automatic channel selection).22
A.8 Test for subclause 5.8 (hand-shaking sequences) .22
A.8.1 Call mode modem (CMM).22
A.8.2 Answer mode modem (AMM).23
A.9 Test for subclause 5.10 (scrambler and descrambler).24
A.9.1 Test for modems which can be operated in the synchronous mode of use .24
A.9.2 Test for modems which can only be operated in a asynchronous mode of use .24
A.10 Test for subclause 5.11 (test loop 2).25
A.10.1 Instigation of remote test loop 2 .25
A.10.1.1 Transmission of the test loop initiation signal (controlling modem under
test) .25
A.10.1.2 Response to the test loop initiation signal (controlled modem under test ) .25
A.10.2 Deactivation of remote test loop 2 .26
A.10.2.1 Transmission of the deactivation signal(controlling modem under test) .26
A.10.2.2 Response to the deactivation signal (controlled modem under test) .26
Annex B (normative): Derivation of timings.27
Annex C (informative): Example proforma for the declaration of modes of operation/use.28
Annex D (informative): Bibliography.30
History .31

Page 5
ETS 300 116: 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 22.
This ETS contains the technical requirements for approval to Category II of 1200 bits per second duplex
modems standardized for use on the Public Switched Telephone Network (PSTN). Approval and testing to
Category II is applicable only at the request of the applicant. These requirements are based on, and do not
conflict with, CCITT Recommendation V.22 [1].
Additional 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.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.
Clause 5 of this ETS contains Category II requirements specific to 1200 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.

Page 6
ETS 300 116: June 1991
Blank page
Page 7
ETS 300 116: June 1991
1 Scope
This ETS specifies the technical characteristics to be met by modems seeking Category II approval for
duplex operation over the PSTN at 1200 bits per second. The modulation scheme specified is that
described in CCITT Recommendation V.22 [1].
NOTE: CCITT Recommendation V.22 [1] also describes a method of transmitting data at 600
bits per second. This ETS specifies the characteristics to be met by such modems and,
if requested by the applicant, this feature can also be approved as Category II.
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 (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): "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".
[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] Draft prETS 300 001 (1990): "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".

Page 8
ETS 300 116: June 1991
3 Definitions and abbreviations
The abbreviations and definitions of ETS 300 114 [2] apply, together with the following.
3.1 Definitions and abbreviations
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
interworking.
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.
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
interworking.
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): the expression "DTE" 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.
Modem: a functional unit that modulates and de-modulates signals in order to enable digital data to be
transmitted over analogue transmission facilities.
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
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 Recommendation(s) of the CCITT as the modem under test,
to the extent necessary for performing the tests;
- 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).
Page 9
ETS 300 116: June 1991
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: are defined as modes specified in this modem specific ETS, that have an influence
upon line signals present at the PSTN interface.
Modes of use: are 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 the on-line state is potentially capable of sending or receiving
speech-band information to or from the network.
Silence: in the context of this ETS, silence is defined as 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
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
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 [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 approval to
Category II is sought.
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.

Page 10
ETS 300 116: June 1991
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 1800 Hz ± 20 Hz, which a modem is to transmit while transmitting in the
high channel;
- signalling rates of 1200 bit/s and, optionally, 600 bit/s.
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.
5.2 Modes
It shall be possible to configure the modem to operate in at least one of the following modes of operation:
- 1200 bit/s call mode;
- 1200 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.
Page 11
ETS 300 116: June 1991
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 1200 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 Clause 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 approval for
Category II is sought.
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 Clause
5.3.2.2.
Compliance shall be checked by the method described in Annex A, Clause 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.
Page 12
ETS 300 116: June 1991
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.
Compliance shall be checked by the method described in Annex A, Clause 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 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). 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 [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 1200 bit/s ± 0,01% and, if requested by the applicant for
approval to Category II, 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.
5.6 Threshold of received line signal detection
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 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.

Page 13
ETS 300 116: June 1991
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, Clause 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 does 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 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.
Page 14
ETS 300 116: June 1991
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 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);
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 1200 bit/s and the guard
tone. When a change from silence to scrambled binary 1 at 1200 bit/s occurs in the line signal received by
the AMM, it shall continue to transmit unscrambled binary 1 at 1200 bit/s and the guard tone for a further
270 ms ± 40 ms followed by scrambled binary 1 at 1200 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);
c) enter the data transmission phase.
For an AMM, conditions a) and b) should occur almost simultaneously. The order is therefore of no
importance.
Page 15
ETS 300 116: June 1991
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 1200 bit/s and, where requested
by the applicant for approval to Category II, 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 ETS 300 114 [2], subclause 5.5.
NOTE: The tests for compliance with the above requirements are described in ETS 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 1s 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, subclause 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 ETS 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
Recommendation CCITT 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 1200 bit/s).

Page 16
ETS 300 116: June 1991
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 ETS 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.

Page 17
ETS 300 116: June 1991
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 ETS 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 modem conformance tester to remain in an on-line state. Unless
otherwise indicated, Test Line 3 (see ETS 300 114 [2], Annex C, Clause C.5) shall be used to connect the
modem under test and the modem conformance tester.
The following information is given to aid the testing authority in determining the signals present on the line.
Unscrambled binary 1 at 1200 bit/s is characterised by tones at 1050 Hz and 1650 Hz for the low channel;
and 2250 Hz and 2850 Hz for the high channel.
Whatever the binary input, scrambled binary signals are characterised by a general distribution of signal
power throughout the frequency band allocated to the particular mode (i.e. 650 Hz to 1750 Hz for call
mode and 1850 Hz to 2950 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 1022 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 / [ETS 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 / ETS 300 114 [2], Clause 4 ; Draft prETS 300 001 [3];

Page 18
ETS 300 116: June 1991
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; ETS 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 / [ETS 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 / [ETS 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 approval.
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
...