ETSI TBR 038 ed.1 (1998-05)
Public Switched Telephone Network (PSTN); Attachment requirements for a terminal equipment incorporating an analogue handset function capable of supporting the justified case service when connected to the analogue interface of the PSTN in Europe
Public Switched Telephone Network (PSTN); Attachment requirements for a terminal equipment incorporating an analogue handset function capable of supporting the justified case service when connected to the analogue interface of the PSTN in Europe
DTBR/ATA-004050
Javno komutirano telefonsko omrežje (PSTN) - Priključitvene zahteve za terminalsko opremo s funkcijo analogne pogovorke, ki lahko podpira storitev v upravičenem primeru, kadar je priključena na analogni vmesnik PSTN v Evropi
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2004
-DYQRNRPXWLUDQRWHOHIRQVNRRPUHåMH 3671 3ULNOMXþLWYHQH]DKWHYH]D
WHUPLQDOVNRRSUHPRVIXQNFLMRDQDORJQHSRJRYRUNHNLODKNRSRGSLUDVWRULWHYY
XSUDYLþHQHPSULPHUXNDGDUMHSULNOMXþHQDQDDQDORJQLYPHVQLN3671Y(YURSL
Public Switched Telephone Network (PSTN); Attachment requirements for a terminal
equipment incorporating an analogue handset function capable of supporting the justified
case service when connected to the analogue interface of the PSTN in Europe
Ta slovenski standard je istoveten z: TBR 038 Edition 1
ICS:
33.040.35 Telefonska omrežja Telephone networks
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL TBR 38
BASIS for May 1998
REGULATION
Source: ATA Reference: DTBR/ATA-004050
ICS: 33.020
Key words: analogue, PSTN, telephony, terminal, type approval
Public Switched Telephone Network (PSTN);
Attachment requirements for a terminal equipment incorporating
an analogue handset function capable of supporting
the justified case service when connected
to the analogue interface of the PSTN in Europe
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Internet: secretariat@etsi.fr - http://www.etsi.fr - http://www.etsi.org
Tel.: +33 4 92 94 42 00 - Fax: +33 4 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 1998. All rights reserved.
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TBR 38: May 1998
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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TBR 38: May 1998
Contents
Foreword .5
Introduction.5
1 Scope .7
2 Normative references.7
3 Definitions, symbols and abbreviations.8
3.1 Definitions .8
3.2 Symbols .9
3.3 Abbreviations .9
4 Speech transmission aspects .9
4.1 General .9
4.1.1 Polarity independence.9
4.1.2 Feed conditions .10
4.1.3 Power supply.10
4.1.4 Volume control .10
4.2 Speech performance characteristics .11
4.2.1 Sensitivity/frequency response.11
4.2.1.1 Sending Sensitivity.11
4.2.1.2 Receiving Sensitivity.12
4.2.2 Sending and Receiving Loudness Ratings (SLR and RLR).13
4.2.2.1 Sending Loudness Rating (SLR) .13
4.2.2.2 Receiving Loudness Rating (RLR) .13
4.2.3 Sidetone .14
4.2.4 Distortion .14
4.2.4.1 Sending distortion.14
4.2.4.2 Receiving distortion .15
4.2.5 Linearity (variation of gain with input level).15
4.2.5.1 Sending linearity .15
4.2.5.2 Receiving linearity.15
4.2.6 Noise .16
4.2.6.1 Sending noise.16
4.2.6.2 Receiving noise .16
4.2.7 Instability.17
4.2.8 Echo Return Loss (ERL) .17
Annex A (normative): Speech transmission compliance tests .18
A.1 General conditions for testing.18
A.1.1 Environment for tests.18
A.1.2 Accuracy of measurements and test equipment setting.18
A.1.3 Order of tests .18
A.1.4 Acoustic environment .19
A.1.5 Handset mounting.19
A.1.6 Test levels.19
A.1.6.1 Sending .19
A.1.6.2 Receiving.19
A.1.6.3 Sidetone .19
A.1.7 Volume control.19
A.1.8 Test equipment requirements.19
A.1.9 Alternative test methods .20
A.1.10 Testing arrangements.20
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TBR 38: May 1998
A.2 Speech transmission performance tests . 23
A.2.1 Sensitivity/frequency response. 23
A.2.1.1 Sending sensitivity . 23
A.2.1.2 Receiving sensitivity. 23
A.2.2 Loudness ratings. 24
A.2.2.1 Sending loudness rating . 24
A.2.2.2 Receiving loudness rating. 24
A.2.3 Sidetone . 25
A.2.4 Distortion . 26
A.2.4.1 Sending distortion . 26
A.2.4.2 Receiving distortion . 27
A.2.5 Linearity (variation of gain with input level). 27
A.2.5.1 Sending linearity . 27
A.2.5.2 Receiving linearity. 28
A.2.6 Noise . 28
A.2.6.1 Sending noise . 28
A.2.6.2 Receiving noise . 28
A.2.7 Instability. 29
A.2.8 Echo Return Loss (ERL) . 31
Annex B (normative): TBR Requirements Table (TBR-RT) . 32
B.1 TBR requirements table. 32
Annex C (informative): Information for test purposes.33
C.1 Introduction. 33
C.2 Guidance for the completion of the information required for test purposes. 33
C.2.1 Options. 33
C.2.2 General information. 33
Annex D (informative): Bibliography . 35
History. 36
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TBR 38: May 1998
Foreword
This Technical Basis for Regulation (TBR) has been produced by the ETSI Project Analogue Terminals
and Access (EP ATA).
The present document has been produced by ETSI in response to a mandate from the European
Commission issued under Council Directive 83/189/EEC (as amended) laying down a procedure for the
provision of information in the field of technical standards and regulations.
The present document is intended to become a Harmonized Standard as requested by the above
mentioned mandate, the reference of which will be published in the Official Journal of the European
Communities referencing the Council Directive relating to telecommunications terminal equipment and
satellite earth station equipment, including the mutual recognition of their conformity (Directive 98/13/EC).
A common technical regulation may be established by the European Commission in accordance with the
Directive.
Technical specifications relevant to the 98/13/EC Directive are given in the TBR-Requirements Table
(TBR-RT) in annex B.
Transposition dates
Date of adoption of this TBR: 01 May 1998
Date of latest announcement of this TBR (doa): 31 August 1998
Date of latest publication of new National Standard
or endorsement of this TBR (dop/e): 31 November 1998
Date of withdrawal of any conflicting National Standard (dow): 31 November 1999
Introduction
This TBR is written in response to an European Commission standardization mandate requesting a
harmonized standard for analogue voice terminals.
The scope of this TBR was laid down by ACTE and the requirements are based on I-ETS 300 677 (Public
Switched Telephone Network (PSTN); Requirements for handset telephony), and on I-ETS 300 480
(Public Switched Telephone Network (PSTN); Testing specification for analogue handset telephony).
This TBR specifies only the technical characteristics for handset telephony and shall be used in
conjunction with an appropriate access standard.
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TBR 38: May 1998
Blank page
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TBR 38: May 1998
1 Scope
This Technical Basis for Regulation (TBR) specifies the technical characteristics (electrical and acoustic
requirements) under Article 5(g) of Directive 98/13/EC to be provided by a single, handset telephony,
terminal equipment which is intended:
a) for pan-European approval; and
b) for connection by 2 wires to an analogue interface of a PSTN. This interface is characterized by a
d.c. loop to indicate seizure and clearing, low frequency a.c. ringing signals below the speech
passband to indicate an incoming call and the transmission phase having an approximate
bandwidth of 3 kHz at the network terminating point; and
c) for supporting the voice telephony justified case service.
The objective of this TBR is to ensure minimum speech quality when interworking via the public network
between two single items of equipment.
This TBR only applies to terminal equipment supporting handset telephony.
This TBR is applicable to handset telephony function. In the case of multiple functions provided in the
same terminal equipment, this TBR does not apply when those other functions are active in conjunction
with handset telephony.
This TBR specifies the functions necessary to provide 2-way real-time speech conversation. Where a
function is indicated as optional, it need not be provided, but, where such a function is provided, the
terminal needs to conform to the requirements and test specified in this TBR.
A test is given for each requirement in this TBR including measurement methods. The terminal equipment
may be stimulated to perform the tests by additional equipment if necessary.
The application of this TBR is not mandatory for:
a) a handset telephony function with speech transmission performance specially designed for
the disabled (e.g. with amplification of received speech as an aid for the hard of hearing);
b) a handset telephony function employing a radio link (e.g. cordless telephones);
c) a handset telephony function with speech transmission performance specifically designed to
cater for hostile environments;
d) any handsfree or loudspeaking voice telephony function;
e) a handset telephony function employing non-linear or time variant techniques for the
processing of the signal.
NOTE: The terminal equipment may provide additional functions or facilities to that of handset
telephony.
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TBR 38: May 1998
2 Normative references
This TBR incorporates by dated and 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 TBR only when incorporated in it by amendment or revision. For undated references the
latest edition of the publication referred to applies.
[1] ITU-T Recommendation G.122 (03/93): "Influence of national systems on
stability and talker echo in international connections".
[2] I-ETS 300 480: "Public Switched Telephone Network (PSTN); Testing
specification for analogue handset telephony".
[3] ITU-T Recommendation P.64 (04/97): "Determination of sensitivity/frequency
characteristics of local telephone systems".
[4] ITU-T Recommendation P.51 (08/96): "Artificial mouth".
[5] ITU-T Recommendation P.57 (0896): "Artificial ears".
[6] IEC 651: "Sound level meters".
[7] ISO 3 (1973): "Preferred numbers - Series of preferred numbers".
[8] ITU-T Recommendation P.79 (03/93): "Calculation of loudness ratings for
telephone sets".
[9] ITU-T Recommendation O.41 (10/94): "Psophometer for use on telephone-type
circuits".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of this TBR, the following definitions apply:
artificial ear: A device for the calibration of earphones incorporating an acoustic coupler and a calibrated
microphone for the measurement of sound pressure and having an overall acoustic impedance similar to
that of the average human ear over a given frequency band.
Echo Return Loss (ERL): Return loss averaged with 1/f power weighting over the telephone band
(300 Hz - 3 400 Hz), in accordance with clause 4 of ITU-T Recommendation G.122 [1].
handset: A combination of telephone microphone and receiver in a form convenient for holding
simultaneously to mouth and ear, which, when in use, retains the microphone in a position fixed in relation
to the receiver.
handset telephony: A function provided by terminal equipment whereby two-way real-time speech is
supported by means of a handset that forms an integral part of the terminal equipment. The term "live
speech" is also frequently used to describe "real-time speech". For the purposes of this TBR, they should
be considered as having the same meaning.
handsfree function: A function whereby telephony transmission and reception is facilitated by the use of
microphone(s) and loudspeaker(s) placed at a distance from the user. No handset is required to be used
and normally the handset is not active.
loop state: The state where the TE draws sufficient DC current to activate the exchange.
loop steady state: A loop state excluding the transitions from and to quiescent state.
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TBR 38: May 1998
loudness rating: A measure, expressed in decibels, for characterizing the loudness performance of
complete telephone connections or of parts thereof such as sending system, line, receiving system.
loudspeaking function: A function of a handset telephone using a loudspeaker associated with an
amplifier as a telephone receiver.
Mouth Reference Point (MRP): A point 25 mm in front of and on the axis of the lip position of a typical
human mouth (or artificial mouth).
nominal setting: A setting of the volume control where the RLR is as close as possible to -8 dB.
3.2 Symbols
For the purposes of this TBR, the following symbols apply:
WOhm
dB decibel
dBPa sound pressure level with respect to 1 Pa, expressed in dB
dBPa(A) "A" weighted sound pressure level with respect to 1 Pa, expressed in dB
dBV voltage level with respect to 1 V, expressed in dB
dBVp psophometrically weighted voltage level with respect to 1 V, expressed in dB
Pa Pascal
SPL Sound Pressure Level
V Volt
3.3 Abbreviations
For the purposes of this TBR, the following abbreviations apply:
a.c. alternating current
d.c. direct current
e.m.f. electromotive force
ERL Echo Return Loss
ERP Ear Reference Point
ITU-T International Telecommunications Union -Telecommunications sector
LRGP Loudness Rating Guard-ring Position
MRP Mouth Reference Point
PSTN Public Switched Telephone Network
r.m.s. root mean square
RL Return Loss
RLR Receiving Loudness Rating
SLR Sending Loudness Rating
STMR SideTone Masking Rating
TBR-RT Technical Basis for Regulation - Requirements Table
TE Terminal Equipment
4 Speech transmission aspects
4.1 General
4.1.1 Polarity independence
Reference: I-ETS 300 677, subclause 4.1.1.
Requirement: The TE shall conform to the requirements of this TBR for both polarities of line feeding
voltage.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to provide
adequate speech performance with both feed polarities, since a fixed polarity is not guaranteed by the
PSTN.
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TBR 38: May 1998
Test: Compliance shall be demonstrated by reversal of the d.c. voltage applied to the line terminals from
test to test or between changes of test configuration when performing the tests of annex A.
4.1.2 Feed conditions
Reference: I-ETS 300 677, subclause 4.1.2.
Requirement: The TE shall conform to the requirements of this TBR when tested with a supply voltage of
50 V and with feed resistances ranging from 500 W to 2 800 W.
NOTE: Some requirements are only specified for single or specific values of feed resistance.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to provide
adequate speech performance over the range of feed conditions occurring in the loop steady state when
connected to the PSTN.
Test: Compliance shall be demonstrated by performing the tests of annex A with the feed resistances
specified in subclause 4.2 which are chosen from those permitted by I-ETS 300 480 [2].
4.1.3 Power supply
Reference: I-ETS 300 677, subclause 4.1.3.
Requirement: Where the terminal handset function is intended to be used with power additional to that
derived from the network, the requirements of subclause 4.2 shall apply only when such additional power
is provided and operating within specification.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires any TE which
needs a source of external power for its speech functions to have adequate speech performance when its
power supply is connected and operative.
Test: Compliance shall be demonstrated by performing the tests of annex A with the power supply
connected and operative.
4.1.4 Volume control
Reference: I-ETS 300 677, subclause 4.1.4.
Requirement: For TE with a user-controlled receiving volume control, the speech performance
characteristics requirements apply with the user-controlled receiving volume control at the setting where
the RLR is as close as possible to -8 dB, unless stated otherwise. This setting is to be taken as the
nominal setting of the volume control.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to provide
adequate speech performance for at least one setting of the volume control.
Test: Compliance tests of annex A shall be carried out at the setting of the volume control where the RLR
is as close as possible to -8 dB when measured with the feed resistance R set to 1 000 W, unless
f
otherwise specified in the appropriate requirement.
NOTE: It is not necessary to strive to achieve values closer than 1 dB.
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TBR 38: May 1998
4.2 Speech performance characteristics
4.2.1 Sensitivity/frequency response
4.2.1.1 Sending Sensitivity
Reference: I-ETS 300 677, subclause 4.2.1.1.
Requirement: The sending sensitivity when measured according to ITU-T Recommendation P.64 [3] with
a load of 600 W, as a function of frequency, shall be not greater than the upper limit and not less than the
lower limit given in table 1 and shown in figure 1.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to have a
sensitivity/frequency response compatible with the network and with other telephones connected to the
network so as to be capable of providing adequate speech performance.
Test: Compliance shall be checked by the test described in subclause A.2.1.1 when measured with the
feed resistance R set to 1 000 W.
f
Table 1: Co-ordinates of sending sensitivity limit curves
Frequency (Hz) dB relative to arbitrary level
Upper limit 100 -9
2 000 +4
4 000 +4
8 000 -13
Lower limit 300 -14
2 000 -6
3 400 -11
Sensitivity
dB rel.
arbitrary zero
-5
-10
-15
100 500 1 000 2 000 5 000 10 000
Frequency (Hz)
Figure 1: Sending sensitivity/frequency limits
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TBR 38: May 1998
4.2.1.2 Receiving Sensitivity
Reference: I-ETS 300 677, subclause 4.2.1.2.
Requirement: The receiving sensitivity when measured according to ITU-T Recommendation P.64 [3], as
a function of frequency, shall be not greater than the upper limit and not less than the lower limit given in
table 2 and shown in figure 2.
Additionally, the sensitivity at 8 kHz shall be at least 20 dB below the sensitivity at 1 kHz.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to have a
sensitivity/frequency response compatible with the network and with other telephones connected to the
network so as to be capable of providing adequate speech performance.
Test: Compliance shall be checked by the test described in subclause A.2.1.2 when measured with the
feed resistance R set to 1 000 W.
f
Table 2: Co-ordinates of receiving sensitivity limit curves
Frequency (Hz) dB relative to arbitrary level
Upper limit 100 -10
200 +2
4 000 +2
8 000 -15
Lower limit 300 -9
1 000 -7
3 400 -12
Sensitivity
dB rel.
arbitrary zero
-5
-10
-15
100 500 1 000 2 000 5 000 10 000
Frequency (Hz)
Figure 2: Receiving sensitivity/frequency limits
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TBR 38: May 1998
4.2.2 Sending and Receiving Loudness Ratings (SLR and RLR)
4.2.2.1 Sending Loudness Rating (SLR)
Reference: I-ETS 300 677, subclause 4.2.2.1.
Requirement: The Sending Loudness Rating (SLR) shall be +3 dB – 4 dB when measured with the feed
resistance R set to 2 800 W and 1 000 W and +3 dB + 7/- 4 dB when measured with the feed resistance
f
R set to 500 W.
f
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the requirement to measure with R set to 2 800 W shall be replaced by a
f
requirement to measure with R set to 2 300 W.
f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to have a
SLR compatible with other telephones connected to the network so as to be capable of providing
adequate speech performance. It is also essential that the terminal performance permits a network
transmission plan capable of meeting ITU-T Recommendations at the international boundary.
Test: Compliance shall be checked by the test described in subclause A.2.2.1.
4.2.2.2 Receiving Loudness Rating (RLR)
Reference: I-ETS 300 677, subclause 4.2.2.2.
Requirement: The Receiving Loudness Rating (RLR) shall be -8 dB – 4 dB when measured with the feed
resistance R set to 2 800 W and 1 000 W and -8 dB + 7/- 4 dB when measured with the feed resistance R
f f
set to 500 W.
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the requirement to measure with R set to 2 800 W shall be replaced by a
f
requirement to measure with R set to 2 300 W.
f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to have a
RLR compatible with other telephones connected to the network so as to be capable of providing
adequate speech performance. It is also essential that the terminal performance permits a network
transmission plan capable of meeting ITU-T Recommendations at the international boundary.
Test: Compliance shall be checked by the test described in subclause A.2.2.2.
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TBR 38: May 1998
4.2.3 Sidetone
Reference: I-ETS 300 677, subclause 4.2.3.
Requirement: When measured by the test described in subclause A.2.3, the SideTone Masking Rating
(STMR) shall be not less than the value shown in table 3 for each termination specified in that table.
Table 3: Sidetone rating
Value of SideTone Masking Rating (dB)
Termination of Termination of Termination of
figure A.6 figure A.7 figure A.8
STMR STMR STMR
‡ +5‡ +10‡ +7
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE to have a
sidetone performance which neither disturbs the user nor interferes with the speech levels to such an
extent as to render the telephone incompatible with adequate speech performance and with ITU-T
Recommendations.
Test: Compliance shall be checked by the test described in subclause A.2.3.
4.2.4 Distortion
4.2.4.1 Sending distortion
Reference: I-ETS 300 677, subclause 4.2.4.1.
Requirement: The "total" harmonic distortion (summed up to the 5th harmonic) for fundamental
frequencies in the range 315 Hz to 1 000 Hz shall be not greater than 7 % with an input of -4,7 dBPa when
measured with a load of 600 W.
With a sinusoidal input signal of +5 dBPa at a frequency of 1 000 Hz, the "total" harmonic distortion
(summed up to the 5th harmonic) shall be not greater than 10 %.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to
produce distortion of the transmitted speech signals sufficient to interfere with adequate speech
performance.
Test: Compliance shall be checked by the test described in subclause A.2.4.1 with the feed resistance R
f
set to 2 800 W and 500 W.
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the test with R set to 2 800 W shall be replaced by a test with R set to 2 300 W.
f f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
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TBR 38: May 1998
4.2.4.2 Receiving distortion
Reference: I-ETS 300 677, subclause 4.2.4.2.
Requirement: The "total" harmonic distortion (summed up to the 5th harmonic) for fundamental
frequencies in the range 315 Hz to 1 000 Hz shall be not greater than 7 %, when measured with an input
e.m.f. of -12 dBV.
With an input e.m.f. of 0 dBV at a frequency of 1 000 Hz, the "total" harmonic distortion (summed up to the
5th harmonic) shall be not greater than 10 %.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to
produce distortion of the received speech signals sufficient to interfere with adequate speech
performance.
Test: Compliance shall be checked by the test described in subclause A.2.4.2 with the feed resistance R
f
set to 2 800 W and 500 W.
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the test with R set to 2 800 W shall be replaced by a test with R set to 2 300 W.
f f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
4.2.5 Linearity (variation of gain with input level)
4.2.5.1 Sending linearity
Reference: I-ETS 300 677, subclause 4.2.5.1.
Requirement: The sensitivity determined with an input sound pressure level of -4,7 dBPa shall not differ
by more than –2 dB from the sensitivity determined with an input sound pressure level of -19,7 dBPa when
measured with a load of 600 W.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to vary
its response to input speech signals sufficient to interfere with adequate speech performance.
Test: Compliance shall be checked by the test described in subclause A.2.5.1 with the feed resistance R
f
set to 1 000 W.
4.2.5.2 Receiving linearity
Reference: I-ETS 300 677, subclause 4.2.5.2.
Requirement: The sensitivity determined with an input signal with an e.m.f. of -12 dBV shall not differ by
more than –2 dB from the sensitivity determined with an input signal with an e.m.f. of -32 dBV.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to vary
its response to received speech signals sufficient to interfere with adequate speech performance.
Test: Compliance shall be checked by the test described in subclause A.2.5.2 with the feed resistance R
f
set to 1 000 W.
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TBR 38: May 1998
4.2.6 Noise
4.2.6.1 Sending noise
Reference: I-ETS 300 677, subclause 4.2.6.1.
Requirement: The psophometrically weighted noise produced by the apparatus in the sending direction
shall be not greater than -66 dBVp when the feed resistance R is set to 500 W, -64 dBVp when the feed
f
resistance R is set to 1 000 W, and -60 dBVp when the feed resistance R is set to 2 800 W.
f f
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the requirement to measure with R set to 2 800 W shall be replaced by a
f
requirement to measure with R set to 2 300 W.
f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to
generate noise levels sufficient to interfere with adequate speech performance or to be incompatible with
ITU-T Recommendations.
Test: Compliance shall be checked by the test described in subclause A.2.6.1.
4.2.6.2 Receiving noise
Reference: I-ETS 300 677, subclause 4.2.6.2.
Requirement: The A-weighted noise produced by the apparatus in the receiving direction shall be not
greater than -49 dBPa(A).
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to
generate noise levels sufficient to interfere with adequate speech performance or to be incompatible with
ITU-T Recommendations.
Test: Compliance shall be checked by the test described in subclause A.2.6.2 with the feed resistance R
f
set to 2 800 W and 500 W.
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the test with R set to 2 800 W shall be replaced by a test with R set to 2 300 W.
f f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
Page 17
TBR 38: May 1998
4.2.7 Instability
Reference: I-ETS 300 677, subclause 4.2.8.
Requirement: Instability (sustained audible oscillations), shall not be induced when the volume control is
set to give maximum receiving gain and the apparatus is subjected to the conditions specified in the
compliance test described in subclause A.2.7.
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to be
so unstable as to prevent the TE from operating in the normal speech mode or to be incompatible with
ITU-T Recommendations.
Test: Compliance shall be checked by the test described in subclause A.2.7.
4.2.8 Echo Return Loss (ERL)
Reference: I-ETS 300 677, subclause 4.2.7.
Requirement: The Echo Return Loss (ERL) shall be not less than 14 dB with respect to the impedance
shown in figure 3.
270 ohms 750 ohms
150 nF
Figure 3: Terminating impedance
Justification: 98/13/EC, Article 5(g).
Interworking of terminal equipment via the public telecommunications network requires the TE not to
cause echo of sufficient magnitude as to interfere with adequate speech performance.
Test: Compliance shall be checked by determination of the echo loss as described in subclause A.2.8
with the feed resistance R set to 2 800 W and 500 W.
f
For terminal equipment supporting handsfree or loudspeaking functions which is not powered from a
separate power supply, the test with R set to 2 800 W shall be replaced by a test with R set to 2 300 W.
f f
NOTE: In some countries, lines are in use which provide less current than that provided by this
test. When connected to such lines, TEs with handsfree or loudspeaking functions
may not operate correctly.
Page 18
TBR 38: May 1998
Annex A (normative): Speech transmission compliance tests
A.1 General conditions for testing
A.1.1 Environment for tests
The following conditions shall apply for the testing environment:
a) Ambient temperature: 15°C to 35°C (inclusive);
b) Relative humidity: 5 % to 85 %;
c) Air pressure: 86 kPa to 106 kPa (860 mbar to 1 060 mbar).
A.1.2 Accuracy of measurements and test equipment setting
Unless specified otherwise, the accuracy of measurements made by test equipment shall be equal to or
better than:
Table A.1: Accuracy of measurements
Item Accuracy
Electrical signal level ±0,2 dB for levels ‡ -50 dBV
±0,4 dB for levels < -50 dBV
Sound pressure ±0,7 dB
Frequency ±0,2 %
Unless specified otherwise, the accuracy of the signals generated by the test equipment shall be better
than:
Table A.2: Accuracy of signals
Quantity Accuracy
Sound pressure level at ±3 dB for frequencies from 100 Hz to 200 Hz
Mouth Reference Point (MRP) ±1 dB for frequencies from 200 Hz to 4 000 Hz
±3 dB for frequencies from 4 000 Hz to 8 000 Hz
Electrical excitation levels ±0,4 dB across the whole frequency range.
Frequency generation ±2 % (see note)
Specified component values ±1 %
NOTE: This tolerance may be used to avoid measurements at critical frequencies,
e.g. those due to sampling operations within the terminal under test.
For terminal equipment which is directly powered from the mains supply, all tests shall be carried out
within –5 % of the rated voltage of that supply. If the equipment is powered by other means and those
means are not supplied as part of the apparatus, all tests shall be carried out within the power supply limit
declared by the supplier. If the power supply is a.c., the test shall be conducted within –4 % of the rated
frequency.
A.1.3 Order of tests
Tests are made in any order except where otherwise specified.
Where testing involves taking measurements using different feeding resistances, measurements shall be
made with the highest feed resistance, then at lower values of resistance, decreasing sequentially to the
minimum, in order to avoid a heating effect in the test arrangement.
Page 19
TBR 38: May 1998
A.1.4 Acoustic environment
Acoustic tests shall be carried out in an environment where the ambient noise is insufficient to influence
the acoustic measurements being made.
Tests for noise and Echo Return Loss (ERL) shall be carried out in an environment where the ambient
noise is less than -64 dBPa(A).
A.1.5 Handset mounting
Unless otherwise stated in a particular test, where the mouthpiece of the TE is fixed relative to the earcap,
the handset shall be placed in the Loudness Rating Guard-ring Position (LRGP) as described in annex C
of ITU-T Recommendation P.64 [3].
In the case of a moveable microphone part, measurements are to be carried out at the setting for normal
usage as defined by the manufacturer.
Where the mouthpiece of the TE is separate from the earpiece, the front plane of the mouthpiece shall be
mounted 15 mm in front of the lip ring and coaxial with the artificial mouth.
The earcap shall be applied to the artificial ear.
A.1.6 Test levels
A.1.6.1 Sending
Unless otherwise stated in this TBR, a pure tone signal with a sound pressure level of -4,7 dBPa shall be
applied at the Mouth Reference Point (MRP) as described in ITU-T Recommendation P.64 [3].
A.1.6.2 Receiving
Unless otherwise stated in this TBR, a pure tone signal with an e.m.f. of -12 dBV from a 600 W resistive
source shall be connected between the terminals A and B shown in figure A.1.
A.1.6.3 Sidetone
Unless otherwise stated in this TBR, a pure tone signal with a sound pressure level of -4,7 dBPa shall be
applied at the Mouth Reference Point (MRP) as described in ITU-T Recommendation P.64 [3].
A.1.7 Volume control
Where a user-controlled volume control is provided, compliance tests shall be carried out at a setting of
the volume control as specified in the appropriate requirement.
If no setting of the volume control is specified, compliance tests shall be carried out at the nominal setting
of the volume control defined in subclause 4.1.4.
A.1.8 Test equipment requirements
Artificial mouth: the artificial mouth shall conform to ITU-T Recommendation P.51 [4].
Artificial ear: the ITU-T Recommendation P.57 [5] Type 1 shall normally be used unless another artificial
ear described in that Recommendation is requested by the terminal supplier.
Where a Type 1 ear is not used:
a) the sound pressure measurements shall be referred to the Ear Reference Point (ERP) by the
correction characteristics specified in ITU-T Recommendation P.57 [5];
b) no leakage correction shall be made in the calculations of RLR (i.e. L = 0).
E
Sound level measuring equipment: the sound level measuring equipment shall conform to IEC 651 [6],
Type 1.
Page 20
TBR 38: May 1998
A.1.9 Alternative test methods
The requirements of this test specification were written on the basis of the standard test methods
described in this TBR. For some parameters it is recognized that alternative test methods may exist. It is
the responsibility of the test house to ensure that any alternative method used is equivalent to that
described in this TBR.
For TE with adaptive modification of any transmission parameter dependent on the electrical operating
conditions e.g. automatic adjustment of sidetone balance, each of the feed conditions for the compliance
tests for the transmission parameters should be treated as a new installation and should be conditioned
according to any instructions provided by the supplier.
A.1.10 Testing arrangements
All tests for transmission performance shall be carried out with the TE connected to the test arrangement
shown in figure A.1. The values of the feed resistance R are chosen appropriate to the requirement under
f
test.
A C
C
(see note 2) f
L
f TE
Artificial mouth
(see note 3)
B D
C
f
L
f Artificial ear
R
(see note 3)
f
I
f
Feeding circuit
(see note 1)
50 V
NOTE 1: The d.c. feeding circuit shown is an i
...
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