SIST I-ETS 300 245-2 E2:2003
(Main)Integrated Services Digital Network (ISDN); Technical characteristics of telephony terminals; Part 2: PCM A-law handset telephony
- Abstract
To prepare an amendment sheet to, or a new edition of I-ETS 300 245-2 to include a full test description and to restructure the ISDN telephony terminal standards with the objective to make the structure easier to understand for the users.
- Status
- Published
- Publication Date
- 30-Nov-2003
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Dec-2003
- Due Date
- 01-Dec-2003
- Completion Date
- 01-Dec-2003
SIST I-ETS 300 245-2 E2:2003 is the Slovenian adoption of ETSI I-ETS 300 245-2 Edition 2 for Integrated Services Digital Network (ISDN) telephony terminals. It specifies the technical characteristics for Pulse Code Modulation (PCM) A-law handset telephony at the basic access, and it is meant for terminal makers, test houses, and approval or quality teams that need a common way to check speech performance.
The document focuses on handset telephony terminals at the coincident S and T reference point and is used together with Part 1. In practice, it tells readers what performance to check, how to test it, and which extra characteristics apply beyond the general ISDN terminal requirements.
What does SIST I-ETS 300 245-2 E2:2003 specify?
SIST I-ETS 300 245-2 E2:2003 specifies the technical characteristics for PCM A-law 3,1 kHz handset telephony terminals used at ISDN basic access. It adds requirements to Part 1 and makes the structure of the ISDN telephony terminal standards easier to follow.
The document is organized into seven main clauses and three annexes.
| Annex | What it covers |
|---|---|
| Annex A | Normative test specifications and test methods |
| Annex B | Informative acoustic shock requirements |
| Annex C | Informative bibliography |
Main clause topics are:
- Clause 1 - Scope
- Clause 2 - Normative references
- Clause 3 - Definitions and abbreviations
- Clause 4 - Call control functions
- Clause 5 - Transmission aspects
- Clause 6 - Power feeding
- Clause 7 - Physical modules
The scope also states that the present version does not cover measurements on receivers in handsets with low acoustic output impedance.
What are the key requirements of SIST I-ETS 300 245-2 E2:2003?
SIST I-ETS 300 245-2 E2:2003 is mainly about speech transmission quality, measured performance, and the test methods used to show conformance. The requirements matter because they determine whether a handset sounds natural, avoids echo and noise, and behaves consistently in real use.
Base ISDN and coding requirements
- Clause 4 requires compliance with Part 1 for call control functions. That means this part is not standalone - users need Part 1 for the general ISDN terminal framework.
- Clause 5.1 sets A-law encoding at 64 kbit/s as the default speech coding. If a terminal uses something else, it is additional rather than replacing the A-law basis.
- Clause 5.1.2 defines the digital interface as the 0 dBr point. This gives a common reference for level measurements and loudness calculations.
- Clause 5.1.3 says the receiving volume control, if present, applies to the requirements unless stated otherwise. In practice, conformance testing must consider the full control range where relevant.
Speech quality requirements
- Clause 5.2.1 sets sending and receiving frequency-response limits for the mouth path and ear path. These are the basic speech-band shape requirements that affect intelligibility and naturalness.
- Clause 5.2.2 gives nominal loudness ratings: Sending Loudness Rating (SLR) and Receiving Loudness Rating (RLR), with manufacturing tolerance allowed. If the terminal has volume control, the RLR must meet the specified bounds at appropriate settings.
- Clause 5.2.3 controls sidetone through SideTone Masking Rating (STMR) and Listener SideTone Rating (LSTR). This matters because too much sidetone makes the user hear their own voice too strongly, while too little can make speech feel unnatural.
- Clause 5.2.4 sets Terminal Coupling Loss (TCL) and Weighted Terminal Coupling Loss (TCLw) limits, plus a stability-loss requirement. These reduce echo and unwanted feedback, especially when the handset is handled close to other surfaces.
Distortion, gain, noise, and out-of-band behavior
- Clause 5.2.5 covers distortion in sending, receiving, and sidetone paths, using both pseudo-random noise and sinusoidal methods. The standard accepts two test methods because different labs may use different equipment, but the measured distortion must still stay within the stated limits.
- Clause 5.2.6 covers variation of gain with input level. This is important when terminals use switch-gain or other non-linear techniques, because the document allows equivalent evaluation methods if they are documented and accepted by the test house.
- Clause 5.2.7 limits out-of-band signals in both directions. In practice, this checks that the terminal does not leak or create unwanted image frequencies outside the speech band.
- Clause 5.2.8 sets noise limits for sending and receiving, including the level of the sampling frequency in receive mode. This helps control background hiss, codec artifacts, and audible tonal components.
- Clause 5.2.10 limits total group delay from the mouth path to the digital interface and back to the ear path. Lower delay matters for conversational quality because excessive delay makes turn-taking harder.
Physical modules and safety-related guidance
- Clause 6 sends power-feeding requirements back to Part 1.
- Clause 7 gives no normative requirements for the handset itself, but it points to Part 1 for the alerting module.
- Annex B gives guidance on acoustic shock, which is tied to safety concerns. It is informative, but it is useful for suppliers who need a basis for self-declaration.
What terms does SIST I-ETS 300 245-2 E2:2003 define?
- Acoustic Reference Level (ARL) - The acoustic level that produces -10 dBm0 at the digital interface.
- digital interface - The B-channels available at the coincident S and T reference point on an ISDN basic access.
- handsfree telephony terminal - A telephony terminal that uses a loudspeaker with an amplifier instead of a handset.
- loudspeaking telephony terminal - A handset telephony terminal that uses a loudspeaker with an amplifier as the receiver.
- telephony 3,1 kHz teleservice - A bidirectional speech service with 3,1 kHz audio bandwidth using a B-channel for user information and the D-channel for signalling.
- Terminal Coupling Loss (TCL) - The frequency-dependent loss between receiving and sending ports caused by acoustic, electrical, and seismic coupling inside the terminal.
- Weighted Terminal Coupling Loss (TCLw) - The TCL after applying the weighting of CCITT Recommendation G.122.
- Sending Loudness Rating (SLR) / Receiving Loudness Rating (RLR) - Standardized loudness measures for the send and receive paths used to set and compare terminal volume levels.
Who uses SIST I-ETS 300 245-2 E2:2003?
SIST I-ETS 300 245-2 E2:2003 is used by telecom terminal manufacturers, especially teams designing ISDN handset telephony terminals. They use it to set speech performance targets and to design the terminal so that it can be tested against a common benchmark.
Test laboratories and certification bodies use it to run the acoustic and digital measurements in Annex A. Quality managers and buyers use it to compare products and confirm that a terminal meets the expected ISDN speech characteristics before approval, procurement, or release.
It is also relevant to suppliers who need to document equivalent methods for non-linear devices, and to organizations concerned with acoustic shock as a safety issue.
What changed in SIST I-ETS 300 245-2 E2:2003 from the previous edition?
SIST I-ETS 300 245-2 E2:2003 is the second edition of Part 2. The scope states that it was prepared to include a full test description and to restructure the ISDN telephony terminal standards so users can understand them more easily.
Which standards are used with SIST I-ETS 300 245-2 E2:2003?
| Standard | What it contributes |
|---|---|
| I-ETS 300 245-1 | General ISDN telephony terminal requirements, including call control, power feeding, and alerting module requirements |
| CCITT P.10 | Telephone transmission quality and telephone set vocabulary |
| CCITT G.701 | Digital transmission, multiplexing, and PCM vocabulary |
| CCITT G.122 | Weighting used for TCLw |
| CCITT G.711 | PCM A-law voice coding |
| CCITT G.101 | Transmission plan and the 0 dBr point |
| CCITT G.223 | Noise weighting for distortion and noise measurements |
| ITU-T P.51 | Artificial mouth |
| ITU-T P.57 | Artificial ear types and related corrections |
| IEC 651 | Sound level meters |
| CCITT O.133 | Reference codec and PCM encoder/decoder measurement equipment |
| CCITT G.712 | Quantizing distortion performance characteristics |
| ITU-T P.64 | Sensitivity/frequency measurement methods for local telephone systems |
| ISO 3 | Preferred numbers and one-twelfth octave frequency series |
| ITU-T P.79 | Loudness rating calculation for telephone sets |
| IEC 225 | Octave, half-octave, and third-octave band filters |
| CCITT O.131 | Pseudo-random-noise distortion test signal |
| CCITT O.132 | Sinusoidal distortion test signal |
What does the SIST I-ETS 300 245-2 E2:2003 document contain?
The document contains the full set of requirements for handset telephony performance, together with the test set-ups used to check them. Annex A gives the practical procedures for sensitivity response, loudness ratings, sidetone, TCL, distortion, gain variation, out-of-band signals, noise, and delay.
It also includes the supporting figures and tables needed for those tests, such as the response curves, level limits, and the delay-measurement arrangement. Annex B gives acoustic shock guidance for continuous and peak signals, and Annex C lists the bibliography used in the document.
Get Certified
Connect with accredited certification bodies for this standard
ANCE
Mexican certification and testing association.
Intertek Slovenia
Intertek testing, inspection, and certification services in Slovenia.
LNE (Laboratoire National de Métrologie et d'Essais)
French national laboratory for metrology and testing.
Sponsored listings
Frequently Asked Questions
SIST I-ETS 300 245-2 E2:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Integrated Services Digital Network (ISDN); Technical characteristics of telephony terminals; Part 2: PCM A-law handset telephony". This standard covers: To prepare an amendment sheet to, or a new edition of I-ETS 300 245-2 to include a full test description and to restructure the ISDN telephony terminal standards with the objective to make the structure easier to understand for the users.
To prepare an amendment sheet to, or a new edition of I-ETS 300 245-2 to include a full test description and to restructure the ISDN telephony terminal standards with the objective to make the structure easier to understand for the users.
SIST I-ETS 300 245-2 E2:2003 is classified under the following ICS (International Classification for Standards) categories: 33.080 - Integrated Services Digital Network (ISDN). The ICS classification helps identify the subject area and facilitates finding related standards.
SIST I-ETS 300 245-2 E2:2003 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2003
'LJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL ,6'1 ±7HKQLþQHNDUDNWHULVWLNH
WHOHIRQVNLKWHUPLQDORY±GHO 7HOHIRQLMDVSRJRYRUNDPLVSUHWYRUERJRYRUDSR
SUDYLOX3&0$ODZ
Integrated Services Digital Network (ISDN); Technical characteristics of telephony
terminals; Part 2: PCM A-law handset telephony
Ta slovenski standard je istoveten z: I-ETS 300 245-2 Edition 2
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 300 245-2
TELECOMMUNICATION February 1996
STANDARD Second Edition
Source: ETSI TC-TE Reference: RI/TE-04041
ICS: 33.080
ISDN, telephony terminals, handset function
Key words:
Integrated Services Digital Network (ISDN);
Technical characteristics of telephony terminals;
Part 2: PCM A-law handset telephony
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.
Page 2
I-ETS 300 245-2: February 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.
Page 3
I-ETS 300 245-2: February 1996
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions .8
3.2 Abbreviations .9
4 Call control functions.9
5 Transmission aspects .9
5.1 General .9
5.1.1 Encoding .9
5.1.2 Relative level .9
5.1.3 Volume control .9
5.2 Speech performance characteristics .9
5.2.1 Frequency response and sensitivity .9
5.2.1.1 Sending.9
5.2.1.2 Receiving.10
5.2.2 Loudness rating.11
5.2.2.1 Nominal values .11
5.2.2.2 Volume control (optional).11
5.2.3 Sidetone .12
5.2.3.1 Talkers sidetone .12
5.2.3.2 Listeners sidetone.12
5.2.4 Terminal Coupling Loss (TCL) .12
5.2.4.1 Weighted Terminal Coupling Loss (TCLw).12
5.2.4.2 Stability loss.12
5.2.5 Distortion .12
5.2.5.1 Sending.12
5.2.5.1.1 Method 1 (Pseudo random noise) .13
5.2.5.1.2 Method 2 (Sinusoidal signal).13
5.2.5.2 Receiving.13
5.2.5.2.1 Method 1 (Pseudo random noise) .13
5.2.5.2.2 Method 2 (Sinusoidal signal).14
5.2.5.3 Sidetone.14
5.2.6 Variation of gain with input level.14
5.2.6.1 Sending.14
5.2.6.2 Receiving.14
5.2.7 Out-of-band signals.15
5.2.7.1 Discrimination against out-of-band input signals (Sending) 15
5.2.7.2 Spurious out-of-band signals (Receiving).15
5.2.8 Noise .16
5.2.8.1 Sending.16
5.2.8.2 Receiving.16
5.2.8.3 Level of sampling frequency (Receiving).16
5.2.9 Acoustic shock .16
5.2.10 Delay .16
5.3 Non-linear devices .16
6 Power feeding .17
7 Physical modules .17
7.1 Handset.17
7.2 Alerting module.17
Page 4
I-ETS 300 245-2: February 1996
Annex A (normative): Test specifications . 18
A.1 General conditions for testing. 18
A.1.1 Environment for test . 18
A.1.2 Test equipment requirements . 18
A.1.2.1 Electro-acoustic equipment . 18
A.1.2.2 Test equipment for digital telephone sets. 18
A.1.2.2.1 Codec approach and specification. 18
A.1.2.2.2 Direct digital processing approach. 19
A.1.3 Alternative test methods. 19
A.1.4 Accuracy of calibration . 20
A.1.5 Bandwidth. 20
A.2 Speech transmission requirements testing. 20
A.2.1 Sensitivity-frequency response . 20
A.2.1.1 Sending. 20
A.2.1.2 Receiving . 20
A.2.2 Loudness rating. 20
A.2.2.1 Sending loudness rating . 20
A.2.2.2 Receiving loudness rating. 21
A.2.3 Sidetone . 21
A.2.3.1 Talker sidetone . 21
A.2.3.2 Listener sidetone . 21
A.2.4 Terminal coupling loss . 22
A.2.4.1 Weighted terminal coupling loss. 22
A.2.4.2 Stability loss. 22
A.2.5 Distortion . 23
A.2.5.1 Sending. 23
A.2.5.1.1 Method 1 . 23
A.2.5.1.2 Method 2 . 23
A.2.5.2 Receiving . 24
A.2.5.2.1 Method 1 . 24
A.2.5.2.2 Method 2 . 24
A.2.5.3 Sidetone. 24
A.2.6 Variation of gain with input level. 24
A.2.6.1 Sending. 24
A.2.6.2 Receiving . 24
A.2.7 Out-of-band signals. 25
A.2.7.1 Discrimination against out-of-band input signals . 25
A.2.7.2 Spurious out-of-band signals. 25
A.2.8 Noise . 25
A.2.8.1 Sending. 25
A.2.8.2 Receiving . 25
A.2.8.3 Level of sampling frequency (receiving) . 25
A.2.9 Delay . 25
Annex B (informative): Acoustic shock requirements. 28
B.1 Continuous signal . 28
B.2 Peak signal . 28
Annex C (informative): Bibliography . 29
History. 30
Page 5
I-ETS 300 245-2: February 1996
Foreword
This second edition of 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 ETS, have it's life extended for a further
two years, be replaced by a new version, or be withdrawn.
Part 2 of this I-ETS specifies technical characteristics for Integrated Services Digital Network (ISDN)
telephony terminals as described in the scope of this I-ETS. The characteristics are additional to type
approval requirements to which the terminal equipment is subject. The additional characteristics are
meant to give improved performance.
This second edition of Part 2 to this I-ETS is the second Part of an I-ETS comprising eight Parts.
Part 1: General.
Part 2: PCM A-law, handset telephony.
Part 3: Pulse Code Modulation (PCM) A-law, loudspeaking and handsfree telephony.
Part 4: Interface for additional equipment to an ISDN telephony terminal.
Part 5: Wideband (7 kHz) handset telephony.
Part 6: Wideband (7 kHz) handsfree telephony.
Part 7: Locally generated information tones.
Part 8: Speech transmission characteristics when using low-delay code-excited linear prediction
coding at 16 kbit/s.
Proposed announcement date
Date of adoption of this I-ETS: 29 February 1996
Date of latest announcement of this I-ETS (doa): 31 May 1996
Page 6
I-ETS 300 245-2: February 1996
Blank page
Page 7
I-ETS 300 245-2: February 1996
1 Scope
This second edition of Part 2 of this Interim European Telecommunication Standard (I-ETS) specifies the
technical characteristics for Pulse Code Modulation (PCM) A-law 3,1 kHz handset telephony terminals to
be used at the basic access for the coincident S and T reference point of the Integrated Services Digital
Network (ISDN).
This Part applies in conjunction with I-ETS 300 245-1 [1] and the characteristics specified in this Part are
additional to those of I-ETS 300 245-1 [1].
The present version of this Part does not cover measurements on receivers (in handsets) with low
acoustic output impedance.
2 Normative references
Part 2 of this I-ETS incorporates by dated or undated reference, provision 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 Part of this I-ETS only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referenced to applies.
[1] I-ETS 300 245-1: "Integrated Services Digital Network (ISDN); Technical
characteristics of telephony terminals; Part 1: General".
[2] CCITT Recommendation P.10 (1988): "Vocabulary of terms on telephone
transmission quality and telephone sets".
[3] CCITT Recommendation G.701 (1988): "Vocabulary of digital transmission and
multiplexing, and pulse code modulation (PCM) terms".
[4] CCITT Recommendation G.122 (1988): "Influence of national systems on
stability, talker echo and listener echo in international connections".
[5] CCITT Recommendation G.711 (1988): "Pulse code modulation (PCM) of voice
frequencies".
[6] CCITT Recommendation G.101 (1988): "The transmission plan".
[7] CCITT Recommendation G.223 (1988): "Assumptions for the calculation of
noise on hypothetical reference circuits for telephony".
[8] ITU-T Recommendation P.51 (1993): "Artificial mouth".
[9] ITU-T Recommendation P.57 (1993): "Artificial ears".
[10] IEC Publication 651: "Sound level meters".
[11] CCITT Recommendation O.133 (1988): "Equipment for measuring the
performance of PCM encoders and decoders".
[12] CCITT Recommendation G.712 (1992): "Transmission performance
characteristics of pulse code modulation".
[13] ITU-T Recommendation P.64 (1993): "Determination of sensitivity/frequency
characteristics of local telephone systems".
[14] ITU-T Recommendation P.64 (1988): "Determination of sensitivity/frequency
characteristics of local telephone systems to permit calculation of their loudness
ratings".
[15] ISO 3 (1973): "Preferred numbers - Series of preferred numbers".
Page 8
I-ETS 300 245-2: February 1996
[16] ITU-T Recommendation P.79 (1993): "Calculation of loudness ratings for
telephone sets".
[17] IEC 225: "Octave, half-octave and third-octave band filters intended for the
analysis of sound and vibrations".
[18] CCITT Recommendation O.131 (1988): "Quantizing distortion measuring
equipment using a pseudo-random noise".
[19] CCITT Recommendation O.132 (1988): "Quantizing distortion measuring
equipment using a sinusoidal test signal".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this I-ETS, the relevant definitions given in CCITT Recommendations P.10 [2] and
G.701 [3] apply along with the following:
Acoustic Reference Level (ARL): The acoustic level which gives - 10 dBm0 at the digital interface.
digital interface: The B-channels available at the coincident S and T reference point at an ISDN basic
access.
handsfree telephony terminal: A telephony terminal using a loudspeaker associated with an amplifier as
a telephone receiver and which can be used without a handset [based on CCITT Recommendation P.10
[2]].
loudspeaking telephony terminal: A handset telephony terminal using a loudspeaker associated with an
amplifier as a telephone receiver [based on in CCITT Recommendation P.10 [2]].
telephony 3,1 kHz teleservice: A teleservice providing speech transmission at an audio bandwidth of
3,1 kHz. The communication is bi-directional, with both directions active during the speech phase. User
information is provided over a B-channel, signalling is provided over the D-channel [based on
ETS 300 111, clause 5].
Terminal Coupling Loss (TCL): The frequency dependent coupling loss between the receiving port and
sending port of a terminal due to:
- acoustic coupling at the user interface;
- electrical coupling due to crosstalk in the handset cord or within the electrical circuits;
- seismic coupling through the mechanical parts of the terminal.
NOTE 1: The receiving port and the sending port of a digital voice terminal is a 0 dBr point.
NOTE 2: The coupling at the user interface will depend on the conditions of use.
Weighted Terminal Coupling Loss (TCLW): The weighted TCL using the weighting of CCITT
Recommendation G.122 [4].
Page 9
I-ETS 300 245-2: February 1996
3.2 Abbreviations
For the purposes of this I-ETS, the following abbreviations, plus the relevant abbreviations in CCITT
Recommendations P.10 [2] and G.701 [3] apply:
ARL Acoustic Reference Level
ERP Ear Reference Point
ISDN Integrated Services Digital Network
LRGP Loudness Rating Guard-ring Position
MRP Mouth Reference Point
PCM Pulse Code Modulation
RLR Receiving Loudness Rating
SLR Sending Loudness Rating
STMR SideTone Masking Rating
TCL Terminal Coupling Loss
TCLw Weighted Terminal Coupling Loss
4 Call control functions
The requirements of I-ETS 300 245-1 [1] shall be met.
5 Transmission aspects
5.1 General
Recommendations and requirements for PCM A-law handset terminals are given in this second Part of
the I-ETS. For loudspeaking or handsfree terminals or when using other coding algorithms other Parts of
this I-ETS may apply.
5.1.1 Encoding
The default speech encoding algorithm for all telephony terminals shall be the A-law encoding at 64 kbit/s
as defined in CCITT Recommendation G.711 [5]. Any possible other encoding algorithm will be additional.
For some encoding algorithms recommendations are given in other Parts of this I-ETS.
5.1.2 Relative level
The digital interface is defined as a 0 dBr point according to CCITT Recommendation G.101 [6].
5.1.3 Volume control
Unless stated otherwise, the requirements apply for all positions of the user-controlled receiving volume
control, if provided.
5.2 Speech performance characteristics
5.2.1 Frequency response and sensitivity
5.2.1.1 Sending
The sending sensitivity-frequency response (from Mouth Reference Point (MRP) to digital interface) shall
be within the limits restricted by the fully drawn lines in figure 1.
In figure 1, a response is given which is considered to give good quality (naturalness and intelligibility).
The response is drawn on a logarithmic (frequency) - linear (dB sensitivity) scale.
Page 10
I-ETS 300 245-2: February 1996
Figure 1: Sending sensitivity/frequency response
The sensitivity values are dB on an arbitrary scale.
Conformance shall be checked by the tests described in annex A, subclauses A.2.1 and A.2.1.1.
5.2.1.2 Receiving
The receiving sensitivity-frequency response (from digital interface to Ear Reference Point (ERP)) shall be
within the limits restricted by the fully drawn lines in figure 2.
In figure 2, a response is given which is considered to give good quality (naturalness and intelligibility).
The response is drawn on a logarithmic (frequency) - linear (dB sensitivity) scale.
Page 11
I-ETS 300 245-2: February 1996
Figure 2: Receiving sensitivity/frequency response
The sensitivity values are dB on an arbitrary scale.
Conformance shall be checked by the tests described in annex A, subclauses A.2.1 and A.2.1.2.
5.2.2 Loudness rating
5.2.2.1 Nominal values
The nominal values are:
SLR = 7 dB
RLR = 3 dB
A manufacturing tolerance for both Sending Loudness Rating (SLR) and Receiving Loudness Rating
(RLR) of ± 3 dB is allowed.
The nominal value of RLR shall be met for at least one setting of the (optional) volume control.
Conformance shall be checked by measurement of SLR and RLR as described in annex A,
subclause A.2.2.
5.2.2.2 Volume control (optional)
If provided, the volume control shall fulfil the following requirements.
When the volume control is set to its maximum position, or an automatic gain control is present, the RLR
shall not be less than (louder than) - 8 dB.
With the volume control set to its minimum position, the RLR shall not be greater than (quieter than)
18 dB.
Conformance shall be checked by measurement of the RLR as described in annex A, subclauses A.2.2
and A.2.2.2, with the volume control set as specified.
Page 12
I-ETS 300 245-2: February 1996
NOTE: It is recommended that all terminals should offer a manual volume control. For
interworking with some non-ISDN networks, a volume control is particularly important
to solve problems of too low receiving levels.
5.2.3 Sidetone
5.2.3.1 Talkers sidetone
The value of the SideTone Masking Rating (STMR) shall be in the range 13 dB - 18 dB when corrected to
nominal values of SLR and RLR (SLR = 7 dB, RLR = 3 dB).
Where a user-controlled volume control is provided STMR shall meet the requirement given above at the
setting where RLR is equal (or closest) to the nominal value.
Compliance shall be checked by the test described in annex A, subclauses A.2.3 and A.2.3.1.
5.2.3.2 Listeners sidetone
The value of the Listener SideTone Rating (LSTR) shall not be less than 15 dB when corrected to nominal
values of SLR and RLR (SLR = 7 dB, RLR = 3 dB).
Where a user-controlled volume control is provided STMR shall meet the requirement given above at the
setting where RLR is equal (or closest) to the nominal value.
Compliance shall be checked by the test described in annex A, subclauses A.2.3 and A.2.3.2.
5.2.4 Terminal Coupling Loss (TCL)
5.2.4.1 Weighted Terminal Coupling Loss (TCLw)
When corrected to nominal Send Loudness Rating (SLR) and Receive Loudness Rating (RLR), the TCLw
shall not be less than 40 dB.
For all positions of the user controlled volume control the TCLw shall not be less than 35 dB.
Compliance shall be checked by the test described in annex A, subclause A.2.4.1.
NOTE: In order to minimise the annoyance due to echo it is a long term objective to have
TCLw of 46 dB or more.
5.2.4.2 Stability loss
With the handset lying on a hard surface and the transducers facing that surface, the attenuation from the
digital input to the digital output shall be at least 6 dB at all frequencies in the range from 200 Hz to 4 kHz.
Conformance shall be checked by the test described in annex A, subclause A.2.4.2.
5.2.5 Distortion
The requirements for sending and receiving distortion were derived from the quantising distortion limits of
CCITT Recommendation G.712 [12]. This recommendation was written for PCM junctions with a flat
frequency response. The additional factors which have to be taken into account for telephones are the
frequency response, and the noise and harmonic distortion introduced by the electro-acoustic/analogue
parts of the instrument. The limits were calculated by a simple combination of contributions from these
factors. The effect of environmental noise on the measurement was found to be negligible until low
acoustic levels.
5.2.5.1 Sending
The terminal shall meet the requirements of both subclauses 5.2.5.1.1 and 5.2.5.1.2.
Page 13
I-ETS 300 245-2: February 1996
5.2.5.1.1 Method 1 (Pseudo random noise)
The ratio of signal-to-total distortion (harmonic and quantizing) power of the digitally encoded signal output
by the terminal equipment shall be greater than the limits given in table 1 unless the sound pressure at the
Mouth Reference Point (MRP) is greater than + 5 dBPa.
Table 1: Limits for signal-to-total distortion ratio for method 1
Sending level dB Receiving level at the Sending ratio (dB) Receiving Ratio (dB)
relative to ARL digital interface
- 45 - 55 dBm0 5,0 5,0
- 30 - 40 dBm0 20,0 20,0
- 24 - 34 dBm0 25,5 25,5
- 17 - 27 dBm0 30,2 30,6
- 10 - 20 dBm0 32,4 33,0
0 - 10 dBm0 33,0 33,7
+ 4 - 6 dBm0 33,0 33,8
+ 7 - 3 dBm0 20,0 20,0
Limits for intermediate levels are found by drawing straight lines between the break points in table 1 on a
linear (dB signal level) - linear (dB ratio) scale.
Compliance shall be checked by the test described in annex A, subclause A.2.5.1.1.
5.2.5.1.2 Method 2 (Sinusoidal signal)
The ratio of signal-to-total distortion power measured with the proper noise weighting (see table 4 of
CCITT Recommendation G.223 [7]) shall be greater than the limits given in table 2 unless the sound
pressure at the MRP is greater than + 10 dBPa.
Table 2: Limits for signal-to-total distortion ratio for method 2
Sending level dB Receiving level at the Sending Receiving
relative to ARL digital interface Ratio (dB) Ratio (dB)
- 35 - 45 dBm0 17,5
17,5
- 30 - 40 dBm0 22,5 22,5
- 20 - 30 dBm0 30,7 30,5
- 10 - 20 dBm0 33,3 33,0
0 - 10 dBm0 33,7 33,5
+ 7 - 3 dBm0
31,7 31,2
+ 10 0 dBm0 25,5 25,5
Limits for intermediate levels are found by drawing straight lines between the break points in table 2 on a
linear (dB signal level) - linear (dB ratio) scale.
Compliance shall be checked by the test described in annex A, subclause A.2.5.1.2.
5.2.5.2 Receiving
The terminal shall meet the requirements of both subclauses 5.2.5.2.1 and 5.2.5.2.2.
5.2.5.2.1 Method 1 (Pseudo random noise)
The ratio of signal-to-total distortion (harmonic and quantizing) power of the signal in the artificial ear shall
be greater than the limits given in table 1 unless the signal in the artificial ear is greater than + 5 dBPa or
is less than - 50 dBPa.
Compliance shall be checked by the test described in annex A, subclause A.2.5.2.1.
Page 14
I-ETS 300 245-2: February 1996
5.2.5.2.2 Method 2 (Sinusoidal signal)
The ratio of signal-to-total distortion power measured in the artificial ear with the psophometric noise
weighting (see table 4 of CCITT Recommendation G.223 [7]) shall be greater than the limits given in
table 2 (of this I-ETS) unless the signal in the artificial ear is greater than + 10 dBPa or is less than
- 50 dBPa.
Compliance shall be checked by the test described in annex A, subclause A.2.5.2.2.
5.2.5.3 Sidetone
The third harmonic distortion generated by the terminal equipment shall be not greater than 10 %.
Compliance shall be checked
...