SIST I-ETS 300 302-2 E1:2003

• Abstract:

  Standardization of electroacoustical characteristics of videotelephony terminals for ISDN using Pulse Code Modulation (PCM) A-law coding and loudspeaking or handsfree functions

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI I-ETS 300 302-2 ed.1 (1995-12) - Integrated Services Digital Network (ISDN); Videotelephony teleservice; Part 2: Electroacoustic characteristics for 3,1 kHz bandwidth loudspeaking and handsfree terminals

SIST I-ETS 300 302-2 E1:2003 is the Slovenian adoption of ETSI’s interim standard for ISDN videotelephony terminals. It specifies electroacoustic characteristics for 3,1 kHz bandwidth loudspeaking and handsfree functions, using PCM A-law coding and, optionally, LD-CELP speech coding. Engineers, test labs, quality managers and buyers use it to judge the audio performance, measurement setup and conformance points for videotelephony terminals.

What does SIST I-ETS 300 302-2 E1:2003 specify?

SIST I-ETS 300 302-2 E1:2003 specifies the electroacoustic characteristics for 3,1 kHz bandwidth loudspeaking and handsfree functions in videotelephony terminals for ISDN. It is written for terminals connected at the basic access of the coincident S and T reference point, and it focuses on the characteristics that differ from ordinary ISDN 3,1 kHz telephony because videotelephony adds video timing and special measurement conditions.

The document is organized into:

• Scope
• Normative references
• Definitions and abbreviations
• Mode "0U" characteristics
• Characteristics for framed transmission in PCM encoding
• Characteristics for framed transmission in LD-CELP encoding
• Annex A, which is an informative bibliography

Clause 4 and clause 5 apply to all videotelephonic terminals. Clause 6 applies only when the optional LD-CELP encoding mode is implemented.

What are the key requirements of SIST I-ETS 300 302-2 E1:2003?

SIST I-ETS 300 302-2 E1:2003 sets the main audio, delay and noise requirements for videotelephony terminal functions, and it ties many checks to the test methods in I-ETS 300 245-3. In practice, that means the standard tells a manufacturer what to measure, in which operating mode, and how to interpret the audio path of the terminal.

Encoding and operating modes

Clause 4 requires mode 0U at the beginning of a call, with A-law as the default encoding law. Clause 5 says the normal working mode is b1, but most tests are to be performed in a0, with delay tested while video is active. This matters because the measured speech performance has to reflect the terminal’s real videotelephony use, not only a simplified audio-only case.

User position and level setting

Clause 5.1 defines how the user position affects measurements. For compact terminals, measurements are corrected with a factor F based on the distance to a standard user position. For terminals with a separated acoustic front end, the supplier defines the test position. This matters because loudspeaking and handsfree performance depends strongly on geometry.

Loudness, coupling and control range

Clause 5.3 covers SLR and RLR. The standard sets nominal targets with a manufacturing tolerance, and it also requires a user-controlled receiving volume range of at least 15 dB. Clause 5.4 adds TCLw, and says extra delay in the audio path must be taken into account. In practice, these provisions check whether the terminal sounds loud enough, can be adjusted by the user, and remains stable when audio is fed back through the device.

Noise and idle-mode behavior

Clause 5.7 limits sending and receiving noise, and the measurements are made in idle mode. The receiving noise limits apply at maximum volume, including an A-weighted noise check and a third-octave-band check. This matters for product acceptability because idle noise is immediately noticeable to users and often appears in quiet rooms.

Delay, lip synchronisation and echo

Clause 5.8 applies the delay requirements and test methods of I-ETS 300 302-1. Clause 5.9 gives no normative lip synchronisation requirement, but it notes a practical check based on keeping audio-video delay difference small. Clause 5.11 points to the echo-cancelling remarks from I-ETS 300 245-3, with extra attention to the longer audio delay in videotelephony.

Optional LD-CELP mode

Clause 6 applies when LD-CELP at 16 kbit/s is used. The terminal has to show conformance to CCITT Recommendation G.728, and the sending and receiving loudness ratings must stay within a small difference from the PCM-based values. This lets manufacturers support the optional codec without changing the user-facing audio balance.

What terms does SIST I-ETS 300 302-2 E1:2003 define?

SIST I-ETS 300 302-2 E1:2003 defines several terms that matter for measurement and user interaction.

• Acoustic Reference Level (ARL) - The acoustic level that corresponds to -10 dBm0 at the digital interface.
• Hands-Free Reference Point (HFRP) - The calibrated measurement point on the axis of the artificial mouth, 50 cm from the lip ring.
• loudspeaking function - The handset stays in the normal position while sound is presented through the loudspeaker(s).
• hands-free function - The user does not hold a handset to the ear; microphones and loudspeakers may be arranged freely.
• Terminal Coupling Loss (TCL) - The frequency-dependent coupling loss between receiving and sending ports caused by acoustic, electrical or mechanical coupling.
• Weighted Terminal Coupling Loss (TCLw) - TCL with the weighting defined by CCITT Recommendation G.122.
• idle mode - The state when the terminal is not activated by an input signal.
• videotelephony teleservice - A real-time audiovisual service where speech and moving pictures are exchanged over one or two 64 kbit/s circuit-mode connections.

Who uses SIST I-ETS 300 302-2 E1:2003?

SIST I-ETS 300 302-2 E1:2003 is used by terminal designers, audio engineers, test laboratories, conformity assessment teams and quality managers working on ISDN videotelephony equipment. It is also relevant to suppliers who need to declare how a terminal behaves in loudspeaking or handsfree use, especially when LD-CELP is implemented. Buyers and procurement teams can use it to compare terminal designs on objective audio-performance criteria.

What changed in SIST I-ETS 300 302-2 E1:2003 from the previous edition?

SIST I-ETS 300 302-2 E1:2003 is identical to I-ETS 300 302-2 Edition 1.

Which standards are used with SIST I-ETS 300 302-2 E1:2003?

The standard builds on these referenced documents:

• CCITT Recommendation G.711 - Defines PCM coding used for the main A-law requirements.
• CCITT Recommendation G.728 - Defines the optional LD-CELP speech coding mode.
• I-ETS 300 245-3 - Supplies the main loudspeaking and handsfree test methods and related telephony characteristics.
• I-ETS 300 302-1 - Provides the absolute delay requirements and test methods.
• ETS 300 111 - Describes the ISDN 3,1 kHz telephony teleservice.
• ETS 300 145 - Defines videotelephony modes of operation and terminal types.
• ETS 300 144 - Identifies mode 0U in the videotelephony context.
• CCITT Recommendations P.10, G.701 and I.112 - Provide the vocabulary used for telephony, PCM and ISDN terms.

What does the SIST I-ETS 300 302-2 E1:2003 document contain?

SIST I-ETS 300 302-2 E1:2003 contains the scope, the normative references, the defined terms and abbreviations, and the technical clauses for PCM and LD-CELP operation. It gives the measurement framework for user position, volume control, loudness ratings, noise, delay, lip synchronisation and echo-related behavior. It also points to the test methods in I-ETS 300 245-3 and I-ETS 300 302-1 where the detailed measurements are performed.

Annex A is an informative bibliography.

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Integrated Services Digital Network (ISDN); Videotelephony teleservice; Part 2:
Electroacoustic characteristics for 3,1 kHz bandwidth loudspeaking and handsfree
terminals
Ta slovenski standard je istoveten z: I-ETS 300 302-2 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERIM
EUROPEAN I-ETS 300 302-2
TELECOMMUNICATION December 1995
STANDARD
Source: ETSI TC-TE Reference: DI/TE-04008.2
ICS: 33.080
ISDN, videotelephony terminals, 3,1 kHz audio, handsfree, loudspeaking, LD-CELP coding
Key words:
Integrated Services Digital Network (ISDN);
Videotelephony teleservice;
Part 2: Electroacoustic characteristics for 3,1 kHz bandwith
loudspeaking and handsfree terminals
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 - [e-mail]
X.400: Internet:
Tel.: [phone] - Fax: [phone]
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 1995. All rights reserved.
New presentation - see History box

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I-ETS 300 302-2: December 1995
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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I-ETS 300 302-2: December 1995
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions .8
3.2 Abbreviations .9
4 Mode "0U" characteristics .9
4.1 Default encoding law.9
4.2 A-law encoding .9
4.3 μ-law encoding.9
5 Characteristics for framed transmission in PCM encoding .9
5.1 General .9
5.1.1 Encoding .10
5.1.2 Relative level .10
5.1.3 Standard user's position.10
5.1.3.1 "Compact" terminal.10
5.1.3.2 Terminal with separated acoustic front end.10
5.1.4 Volume control .10
5.2 Sensitivity - frequency response .10
5.3 Loudness Ratings (SLR and RLR) .10
5.3.1 Sending Loudness Rating (SLR).11
5.3.2 Receiving Loudness Rating (RLR).11
5.3.2.1 Maximum sensitivity.11
5.3.2.2 Volume control range .11
5.4 Terminal Coupling Loss (TCL).11
5.4.1 Weighted Terminal Coupling Loss (TCLw) .11
5.4.2 Stability.11
5.5 Distortion.11
5.6 Out of band signals.11
5.7 Noise.12
5.7.1 Sending .12
5.7.2 Receiving.12
5.7.2.1 A-weighted noise .12
5.7.2.2 Third octave band spectrum.12
5.8 Absolute delay.12
5.9 Lip synchronisation .12
5.10 Switching characteristics.12
5.11 Echo cancelling characteristics.12
5.12 Articulation .12
6 Characteristics for framed transmission in LD-CELP encoding.13
6.1 General .13
6.2 Sensitivity.13
6.2.1 Sending .13
6.2.2 Receiving.13
Annex A (informative): Bibliography.14
History.15

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I-ETS 300 302-2: December 1995
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I-ETS 300 302-2: December 1995
Foreword
Part 2 of this Interim European Telecommunication Standard (I-ETS) was produced by the Terminal
Equipment (TE) Technical Committee of the European Telecommunications Standards Institute (ETSI).
An ETSI standard may be given I-ETS status either because it is regarded as a provisional solution ahead
of a more advanced standard, or because it is immature and requires a "trial period". The life of an I-ETS
is limited to three years after which it can be converted into an European Telecommunication Standard
(ETS), have it's life extended for a further two years, be replaced by a new version or, be withdrawn.
This is the second Part of an I-ETS which is currently intended to comprise four Parts.
Part 1: Electroacoustic characteristics for handset telephony function when using Pulse Code
Modulation encoding.
Part 2: Electroacoustic characteristics for 3,1 kHz bandwidth loudspeaking and handsfree
terminals.
Part 3: Electroacoustic characteristics for 7 kHz bandwidth handset terminals.
Part 4: Electroacoustic characteristics for 7 kHz bandwidth loudspeaking and handsfree terminals.
Proposed announcement date
Date of adoption of this I-ETS: 1 December 1995
Date of latest announcement of this I-ETS (doa): 31 March 1996

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I-ETS 300 302-2: December 1995
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I-ETS 300 302-2: December 1995
1 Scope
This I-ETS specifies the electroacoustic characteristics for 3,1 kHz bandwidth loudspeaking and
handsfree functions implemented in videotelephony terminals. These terminals are intended for use in the
videotelephony teleservice and connected to the basic access of the coincident S and T reference point of
the Integrated Services Digital Network (ISDN) using either Pulse Code Modulation (PCM) encoding
according to CCITT Recommendation G.711 [1], A-law or low delay code-excited linear prediction (LD-
CELP) coding at 16 kbit/s as specified in CCITT Recommendation G.728 [2].
The videotelephony teleservice in the ISDN is defined in ETS 300 264.
The requirements of clauses 4 and 5 are applicable to all videotelephonic terminals and the requirements
of clause 6 is applicable when the optional LD-CELP encoding is implemented.
The requirements of this I-ETS specify those characteristics which deviate from those an ISDN 3,1 kHz
telephony terminal needs to meet due to conditions which are special for videotelephony applications (e.g.
delay, measurement position). The corresponding requirements to an ISDN 3,1 kHz telephony
loudspeaking and handsfree terminal can be found in I-ETS 300 245-3 [3] and in I-ETS 300 245-8 for
LD-CELP coding.
2 Normative references
This I-ETS 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 I-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 G.711 (1988): "Pulse code modulation (PCM) of voice
frequencies".
[2] CCITT Recommendation G.728 (1992): "Coding of speech at 16 kbit/s using low
delay code excited linear prediction".
[3] I-ETS 300 245-3 (1995): "Integrated Services Digital Network (ISDN); Technical
characteristics of telephony terminals; Part 3: Pulse Code Modulation (PCM)
A-law, loudspeaking and handsfree telephony".
[4] CCITT Recommendation P.10 (1988): "Vocabulary of terms on telephone
transmission quality and telephone sets".
[5] CCITT Recommendation G.701 (1988): "Vocabulary of digital transmission and
multiplexing, and pulse code modulation (PCM) terms".
[6] ETS 300 111 (1992): "Integrated Services Digital Network (ISDN); Telephony
3,1 kHz teleservice, Service description".
[7] ETS 300 145: "Integrated Services Digital Network (ISDN); Audiovisual
teleservices; Videotelephone systems and terminal equipment operating on one
or two 64 kbit/s channels".
[8] CCITT Recommendation I.112 (1988): "Vocabulary of terms for ISDNs".
[9] ETS 300 144: "Integrated Services Digital Network (ISDN); Audiovisual
teleservices; Frame structure for a 64 kbit/s to 1 920 kbit/s channel and
associated syntax for inband signalling".
[10] CCITT Recommendation G.101 (1988): "The transmission plan".
[11] I-ETS 300 302-1: "Integrated Services Digital Network (ISDN); Videotelephony
teleservice, Part 1: Electroacoustic characteristics for telephony function when
using Pulse Code Modulation (PCM) encoding".

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I-ETS 300 302-2: December 1995
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this Part of the I-ETS, the relevant definitions and abbreviations in CCITT
Recommendations P.10 [4] and
...