ETSI EN 300 175-8 V1.4.2 (1999-06)

SLOVENSKI STANDARD
01-julij-2005
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Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 8:
Speech Coding and Transmission
Ta slovenski standard je istoveten z: EN 300 175-8 Version 1.4.2
ICS:
33.070.30 'LJLWDOQHL]EROMãDQH Digital Enhanced Cordless
EUH]YUYLþQHWHOHNRPXQLNDFLMH Telecommunications (DECT)
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 300 175-8 V1.4.2 (1999-06)
European Standard (Telecommunications series)
Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI);
Part 8: Speech coding and transmission

2 ETSI EN 300 175-8 V1.4.2 (1999-06)
Reference
REN/DECT-000129-8 (1me00jdc.PDF)
Keywords
DECT, radio
ETSI
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© European Telecommunications Standards Institute 1999.
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ETSI
3 ETSI EN 300 175-8 V1.4.2 (1999-06)
Contents
Intellectual Property Rights . 6
Foreword. 6
1 Scope. 7
2 References . 8
3 Definitions and abbreviations. 9
3.1 Definitions . 9
3.2 Abbreviations. 10
4 Configurations . 11
4.1 Reference configuration. 11
4.1.1 Basic configuration . 11
4.1.2 Portable Part (PP). 12
4.1.2.1 Functional organization . 12
4.1.2.2 Volume control. 12
4.1.3 Fixed Part (FP). 13
4.1.3.1 Digital interface . 13
4.1.3.2 Analogue interface. 14
4.1.3.3 FP adaptive volume control. 14
4.2 Test configurations . 14
5 Encoding. 14
5.1 32 kbit/s full term (ADPCM). 14
5.1.1 Algorithm . 14
5.1.2 Bit sequence . 15
5.2 Other codings. 15
6 Transmission aspects . 15
6.1 Relative level . 15
6.2 Acoustic reference level. 15
6.3 Volume control . 15
7 Speech performance characteristics . 15
7.1 PP frequency responses . 15
7.1.1 Sending. 15
7.1.2 Receiving . 16
7.2 PP sending and receiving loudness ratings . 16
7.2.1 Nominal values. 16
7.2.2 User-controlled volume control in PP . 16
7.2.3 PP adaptive volume control. 17
7.2.4 FP adaptive volume control. 17
7.3 Sidetone . 18
7.3.1 Talker sidetone. 18
7.3.2 Listener sidetone . 18
7.4 Terminal coupling loss. 18
7.4.1 Weighted Terminal Coupling Loss (TLCw). 18
7.4.1.1 PP for the 3,1 kHz service (PSTN or ISDN) . 18
7.4.1.2 FP with 4-wire interface . 18
7.4.1.3 FP with analogue 2-wire interface . 19
7.4.1.4 PP for unrestricted 64 kbit/s service . 19
7.4.2 Stability loss. 19
7.4.2.1 Requirement . 19
7.4.2.2 Test conditions . 20
7.4.2.3 Fixed geometry PP. 20
7.4.2.4 Variable geometry PP. 20
7.5 Distortion. 20
ETSI
4 ETSI EN 300 175-8 V1.4.2 (1999-06)
7.5.1 Sending. 20
7.5.2 Receiving . 20
7.5.3 Sidetone. 20
7.5.4 Recommended value for network planning . 20
7.6 Out of band signals . 20
7.6.1 Sending (discrimination against out of band input signals). 20
7.6.2 Receiving (spurious out of band signals) . 21
7.7 Noise. 21
7.7.1 Sending. 21
7.7.2 Narrow-band noise . 21
7.7.3 Receiving . 21
7.7.4 Level of sampling frequency (receiving). 21
7.8 Acoustic shock. 21
7.8.1 Continuous signal. 21
7.8.2 Peak signal . 21
7.9 Delay. 22
7.9.1 DECT network . 22
7.9.2 PP. 22
7.9.3 FP. 22
7.10 Network echo control. 22
7.11 PP ambient noise rejection. 23
7.12 Additional requirements for DECT systems provided with a 2-wire PSTN interface. 23
7.12.1 General. 23
7.12.1.1 Polarity independence. 23
7.12.1.2 Feed Conditions. 23
7.12.1.3 Power supply . 23
7.12.2 Speech performance characteristics . 23
7.12.2.1 Sensitivity/frequency response . 24
7.12.2.2 Sending and Receiving Loudness Ratings (SLR and RLR). 24
7.12.2.3 Distortion. 24
7.12.2.4 Noise. 24
7.12.2.5 Echo Return Loss. 24
8 Additional features . 24
8.1 Loudspeaking and hand-free facilities . 24
8.2 Tandem with mobile radio network . 24
8.2.1 Tandem with GSM. 25
8.2.1.1 Network echo control . 25
8.2.1.2 Terminal coupling loss . 25
8.2.1.3 The GSM mobile transmitter operates in continuous mode. 25
8.2.1.4 The GSM mobile transmitter operates in discontinuous mode, DTX. 25
8.3 DECT connected to the GSM fixed network . 25
8.3.1 Network echo control. 26
8.3.2 Terminal coupling loss. 26
8.4 Wireless Relay Stations (WRS) . 26
8.4.1 Modified FP network echo control requirements for implementation of 2 and 3 CRFP links in
cascade . 27
Annex A (informative): Description of "reference" echo control devices. 28
A.1 Handset echo. 28
A.1.1 Overview. 28
A.1.1.1 Connection to the PSTN/ISDN . 28
A.1.1.1.1 Local and national calls . 28
A.1.1.1.2 Long distance connections with echo control devices in the PSTN/ISDN, e.g. calls via satellites. 28
A.1.1.2 Connection to the GSM network. 29
A.1.2 Implementation of the FP echo control function. 29
A.1.2.1 Suppression threshold . 30
A.1.2.2 Static characteristics of activation control. 30
A.1.2.3 Dynamic characteristics of activation control . 30
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5 ETSI EN 300 175-8 V1.4.2 (1999-06)
A.2 Network echo. 30
A.2.1 Soft suppressor implementation of requirement 2. 31
A.2.1.1 Static characteristics. 32
A.2.1.2 Dynamic characteristics . 32
A.2.2 Additional echo control for a 2-wire interface of requirement 1. 32
A.2.3 Echo canceller used for both requirements 1 and 2 . 33
Annex B (informative): Local loop application. 34
B.1 DECT tethered local loop replacement with 2-wire PP end system. 34
B.1.1 TCLw requirements . 34
B.1.2 Network echo. 35
B.2 Quantization distortion considerations. 35
Annex C (informative): GSM Discontinuous Transmission (DTX), and Voice Activity
Detection (VAD) . 36
Annex D (informative): Speech levels in relation to ambient room noise and examples of
adaptive volume control settings . 37
Bibliography . 38
History. 39
ETSI
6 ETSI EN 300 175-8 V1.4.2 (1999-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by ETSI Project Digital Enhanced Cordless
Telecommunications (DECT).
The present document is part 8 of a multi-part EN covering the Common Interface (CI) for the Digital Enhanced
Cordless Telecommunications (DECT), as identified below:
Part 1: "Overview";
Part 2: "Physical layer (PHL)";
Part 3: "Medium Access Control (MAC) layer";
Part 4: "Data Link Control (DLC) layer";
Part 5: "Network (NWK) layer";
Part 6: "Identities and addressing";
Part 7: "Security features";
Part 8: "Speech coding and transmission".
Further details of the DECT system may be found in ETR 015 [18], ETR 043 [19], and ETR 056 [20].
National transposition dates
Date of adoption of this EN: 28 May 1999
Date of latest announcement of this EN (doa): 31 August 1999
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 29 February 2000
Date of withdrawal of any conflicting National Standard (dow): 29 February 2000
ETSI
7 ETSI EN 300 175-8 V1.4.2 (1999-06)
1 Scope
The present document gives an introduction and overview of the complete Digital Enhanced Cordless
Telecommunications (DECT) Common Interface (CI).
This part of the DECT CI specifies the speech coding and transmission requirements.
In order to ensure satisfactory interworking of different portable and fixed units, it is necessary to specify the
transmission performance of the analogue information over the digital link. This requires not only use of a common
speech algorithm, but also standardization of frequency responses, reference speech levels (or loudness) at the air
interface and various other parameters.
The present document applies to DECT equipment which includes all the necessary functions to provide real-time
two-way speech conversation. A 3,1 kHz telephony teleservice conveyed over a DECT link (including Fixed Part (FP)
and Portable Part (PP)) which is capable of being connected (directly or indirectly) to the public network access point
has to comply with the requirements in the present document.
Tethered fixed point local loop applications are not required to comply with the requirements of the present document.
The speech performance characteristics defined in the present document typically conform to TBR 8 [13], which
specifies the overall performance between the handset acoustic interface and a 64 kbit/s A-law Pulse Code Modulated
(PCM) digital network interface. The deviations from TBR 8 [13] are mainly due to the consequences of non-PCM
coding and transmission delay.
The additional features described in clause 8 are those which are not included in TBR 8 [13], but which are likely to
occur in a DECT system: analogue interface, loudspeaking and hand-free facilities, tandeming with a mobile radio
network. Headsets are not covered by the present specifications.
For the DECT systems which connect to the Public Switched Telephone Network (PSTN) via an analogue interface, the
additional requirements, which have to be implemented in the FP, have as much as possible been aligned with
TBR 38 [17].
ETSI/STC TM5 has prepared a technical report, ETR 041 [21], to be used as a guide for network planning.
A summary of the control and the use of the DECT echo control functions, to guide on need for options to
manufacturers and installers, is found in annex A.
Information concerning test methods can be found in EN 300 176 [3]. The test methods take into account that DECT is a
digital system.
ETSI
8 ETSI EN 300 175-8 V1.4.2 (1999-06)
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
• A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
[1] EN 300 175-1: "Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI);
Part 1: Overview".
[2] EN 300 175-5: "Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI);
Part 5: Network (NWK) layer".
[3] EN 300 176: "Digital Enhanced Cordless Telecommunications (DECT); Approval test
specification; (Part 1: Radio; Part 2: Speech)".
[4] ITU-T Recommendation G.101 (1996): "The transmission plan".
[5] ITU-T Recommendation G.131 (1996): "Control of talker echo".
[6] CCITT Recommendation G.164 (1988): "Echo suppressors".
[7] ITU-T Recommendation G.165 (1993): "Echo cancellers".
[8] ITU-T Recommendation G.701 (1993): "Vocabulary of digital transmission and multiplexing, and
pulse code modulation (PCM) terms".
[9] CCITT Recommendation G.726 (1991): "40, 32, 24, 16 kbit/s adaptive differential pulse code
modulation (ADPCM)".
[10] CCITT Recommendation I.241 (1988): "Teleservices supported by an ISDN".
[11] ITU-T Recommendation P.10 (1993): "Vocabulary of terms on telephone transmission quality and
telephone sets".
[12] ITU-T Recommendation P.340 (1996): "Transmission characteristics of hands-free telephones".
[13] TBR 8 (1998): "Integrated Services Digital Network (ISDN); Telephony 3,1 kHz teleservice;
Attachment requirements for handset terminals".
[14] ITU-T Recommendation G.113 (1996): "Transmission impairments".
[15] ITU-T Recommendation G.111 (1988): "Loudness ratings (LRs) in an international connection".
[16] ETS 300 540: "Digital cellular telecommunications system (Phase 2); Transmission planning
aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system
(GSM 03.50)".
[17] TBR 38 (1998): "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".
[18] ETR 015: "Digital Enhanced Cordless Telecommunications (DECT); Reference document".
[19] ETR 043: "Digital Enhanced Cordless Telecommunications (DECT); Common interface; Services
and facilities requirements specification".
ETSI
9 ETSI EN 300 175-8 V1.4.2 (1999-06)
[20] ETR 056: "Digital Enhanced Cordless Telecommunications (DECT); System description
document".
[21] ETR 041: "Transmission and Multiplexing (TM); Digital European Cordless Telecommunication
(DECT); Transmission aspects 3,1 kHz telephony; Interworking with other networks".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Central Control Fixed Part (CCFP): see EN 300 175-1 [1].
Cordless Radio Fixed Part (CRFP): see EN 300 175-1 [1].
DECT Network (DNW): see EN 300 175-1 [1].
double duplex bearer: see EN 300 175-1 [1].
End System (ES): see EN 300 175-1 [1].
fixed geometry Portable Part (PP): PP in which the electro-acoustic transducers and their associated acoustic
components are held in fixed relative positions and/or orientations during all on-line conditions and test conditions of
the PP.
Fixed Part (DECT Fixed Part) (FP): see EN 300 175-1 [1].
Fixed radio Termination (FT): see EN 300 175-1 [1].
Generic Access Profile (GAP): standard in addition to the DECT CI that ensures interoperability between FPs and PPs
from different manufacturers.
handset echo: echo, perceptible by the far-end user, resulting from the coupling between the receiving and sending
directions of the handset, mostly due to acoustic coupling between transducers. It is particularly objectionable in
communications including a satellite and an echo canceller, as the DECT handset echo may be out of range of the echo
canceller.
network (telecommunication network): see EN 300 175-1 [1].
network echo: echo, perceptible by the DECT user, resulting from reflections in the network. It is mostly due to hybrid
impairments at both ends of the communication.
operator (DECT operator): see EN 300 175-1 [1].
Portable Handset (PHS): see EN 300 175-1 [1].
Portable Part (DECT Portable Part) (PP): see EN 300 175-1 [1].
Portable radio Termination (PT): see EN 300 175-1 [1].
public: see EN 300 175-1 [1].
public access service: see EN 300 175-1 [1].
Radio Fixed Part (RFP): see EN 300 175-1 [1].
Repeater Part (REP): see EN 300 175-1 [1].
service provider (telecommunications service provider): see EN 300 175-1 [1].
telephony service: see CCITT Recommendation I.241 [10].
ETSI
10 ETSI EN 300 175-8 V1.4.2 (1999-06)
user (of a telecommunication network): see EN 300 175-1 [1].
variable geometry PP: PP that allows the position and/or orientation of its electro-acoustic transducers and their
associated acoustic components to be changed during all on-line conditions of the PP.
Wireless Relay Station (WRS): see EN 300 175-1 [1].
3.2 Abbreviations
For the purposes of the present document, relevant definitions and abbreviations in ITU-T Recommendation P.10 [11]
and ITU-T Recommendation G.701 [8] apply:
ADPCM Adaptive Differential Pulse Code Modulation
CCFP Central Control Fixed Part
CI Common Interface
CFRP Cordless Radio Fixed Part
CLRR Circuit Loudness Rating, Receiving
CLRS Circuit Loudness Rating, Sending
CRFP Cordless Radio Fixed Part
dBm dB relative to 1 milliwatt
dBm0 The absolute power level in decibels referred to a point of zero relative level
dBr The relative power level in decibels
DECT Digital Enhanced Cordless Telecommunications
DNW DECT Network
ERP Ear Reference Point
ES End System
FP Fixed Part
FT Fixed radio Termination7
GAP Generic Access Profile
ISDN Integrated Services Digital Network
LLe Local Echo Loss
LSTR Listener Sidetone Rating
MRP Mouth Reference Point
NLP Non-Linear Processor
NWK Network
OLR Overall Loudness Rating
P(A)BX Private (Automatic) Branch Exchange
PAP Public Access Profile
PCM Pulse Code Modulated
PHS Portable Handset
PP Portable Part
PSPDN Packet Switched Public Data Network
PSTN Public Switched Telephone Network
PT Portable radio Termination
PTN Private Telecommunication Network
ReFP Reference Fixed Part
RePP Reference Portable Part
REP REpeater Part
RFP Radio Fixed Part
RLRH Receiving Loudness Rating of the Handset
SLRH Sending Loudness Rating of the Handset
TCLw weighted Terminal Coupling Loss
TELR Talker's Echo Loudness Rating
STMR Sidetone Masking Rating
QDU Quantization Distortion Unit
WRS Wireless Relay Station
ETSI
11 ETSI EN 300 175-8 V1.4.2 (1999-06)
4 Configurations
4.1 Reference configuration
4.1.1 Basic configuration
The basic reference configuration for voice transmission over DECT is shown in figure 1.
PP (h andset) FP (fixe d pa rt)
Acoustic Air
interface interface Line
Lin e
MRP
Acoustic interfa ce
Transcoder Transcoder
0 interface +
+ echo
Uniform Uniform
Volume control
PCM PCM
control +
to/from to/from
+ Volum e control
air code air code
+
] coder
coder
ERP
Uniform Uniform
PCM PCM
re feren ce reference
point point
Figure 1: Basic reference configuration
The PP and the FP are delimited by physical interfaces:
- Acoustic: from the PP towards the speaker-listener, with the Ear and Mouth Reference Points (ERP and MRP).
- Air(RF): the interface between PP and FP.
- Line: the interface from the FP towards the network.
Uniform PCM reference points shall be introduced in both the PP and the FP to materialize the limits of the transmission
segment which is affected by the air interface coding scheme. This allows the transmission requirements to be specified
independently from the coding at the air interface. The various transcoding algorithms are level-transparent, i.e. with an
encoder and decoder connected in tandem, the "levels" of the digital signals at the uniform PCM input of the encoder
and output from the decoder are identical. In a particular implementation, the reference points may be embedded within
an IC, and thus will not be physically accessible.
Each of the three sections thus delimited deals with distinct functions:
a) the PP electro-acoustic section (between acoustic interface and PP uniform PCM reference point) which includes
the acoustic interface, the volume control and the analogue to digital conversion;
b) the air-code section (between PP and FP uniform PCM reference points) considers the transcoding between
uniform PCM and the air-code, as well as the transmission over the air interface;
c) the FP line interface section (between FP uniform PCM reference point and line interface) comprises the
interface to the line, digital or analogue, and the FP voice processing, e.g. echo control.
Typically, the transmission features shall conform to TBR 8 [13] for the PP electro-acoustic section, and the line
interface section in the case of digital interface. In the case of analogue interface, the line interface section realizes in the
FP the adaptation to subclause 7.12 and to the relevant attachment requirements.
ETSI
12 ETSI EN 300 175-8 V1.4.2 (1999-06)
4.1.2 Portable Part (PP)
4.1.2.1 Functional organization
Figure 2 represents the basic functional organization of a PP from the voice transmission point of view:
Acoustic Uniform PC M Air
interface reference point interface
SLRH
MRP
A/D
Transcoder
Electro-
Uniform PC M
acoustic
to /fro m
interface
air code
D/A
+
ERP
filter
RLRH
Figure 2: PP functional organization
The various functions represented in figure 2 are:
a) the electro-acoustic function, which performs the interface to the transducers and the volume control. The
Handset Loudness Ratings (SLR ) and (RLR ) are defined between the acoustic interface and the uniform PCM
H H
reference point;
b) the analogue to digital and digital to analogue coding to the uniform PCM reference point;
c) the transcoder between uniform PCM and air-code.
4.1.2.2 Volume control
The volume control facility is optional, and can be implemented in a number of different ways:
1) in the simplest implementation, it affects only the receiving level and is under the manual control of the PP user;
2) the volume adjustment may also be adaptive, e.g. taking into account the average level of ambient noise at the
MRP;
3) the volume control may affect both receiving and sending levels in opposite directions. This has the advantage of
reducing the effect on the terminal coupling loss. Such an implementation would fit a noisy environment, as the
need for an increased receiving volume is likely to come from a loud ambient noise, and it is then combined with
a loud speech level.
ETSI
13 ETSI EN 300 175-8 V1.4.2 (1999-06)
4.1.3 Fixed Part (FP)
4.1.3.1 Digital interface
Figure 3 shows the functional organization of a FP with a digital interface:
Air Uniform PC M Line
in te rfa c e reference point in te rfa c e
Echo
Transcoder Transcoder
control
Uniform PC M Uniform PC M
ha ndset
to /fro m to /fro m
+
air code A-law
netw ork
Figure 3: FP functional organization
The various functions represented in figure 3 are:
a) a transcoder between air-code and uniform PCM;
b) an echo control function which processes echoes coming back from both the handset and the network. It provides
additional losses that compensate for the increased length of the echo path due to the DECT transmission delay
over the air interface;
c) a transcoder from uniform PCM to A-law PCM towards the line interface.
ETSI
14 ETSI EN 300 175-8 V1.4.2 (1999-06)
4.1.3.2 Analogue interface
The organization of a FP with an analogue interface is shown in figure 4.
Air Uniform PC M Line
in te rf a c e refe re nce point in te rf a c e
CLRS
D/A
+
filter
Ech o
Transcoder
control
Unifo rm PC M
to /fr om
in clu d in g
air code
hyb rid
A/D
CLRR
Figure 4: FP with an analogue interface
The various functions represented in figure 4 are:
a) the line interface comprises the digital to analogue coder-decoder and the adaptation to the line, that can be either
2- or 4-wire. The Circuit Loudness Ratings (CLRR and CLRS) are defined between uniform PCM reference
point and the line interface;
b) in the case of a 2-wire line, the network echo controller deals with the local hybrid echo, which is superimposed
on the network echo in a manner similar to the digital line interface.
4.1.3.3 FP adaptive volume control
An adaptive dual volume adjustment, as described in subclause 4.1.2.2, may optionally be implemented into the FP, for
base stations where the associated PPs may be used in a noisy environment (e.g. public access).
4.2 Test configurations
A DECT system comprises a FP and a PP. As these parts are not always purchased together, it is a requirement that
either the complete system or each of the two separate parts shall be capable of being tested (see EN 300 176 [3]).
5 Encoding
5.1 32 kbit/s full term (ADPCM)
5.1.1 Algorithm
The speech coding algorithm shall conform to CCITT Recommendation G.726 [9] for 32 kbit/s Adaptive Differential
Pulse Code Modulation (ADPCM).
The A-law companding and synchronous tandem adjustment maybe omitted in FPs with an analogue line interface and
in PPs.
ETSI
15 ETSI EN 300 175-8 V1.4.2 (1999-06)
NOTE: CCITT Recommendation G.726 [9] 32 kbit/s ADPCM codecs support the use of the voice channel for
telefax of group 2 and group 3. For group 3 the data speed, which is automatically negotiated, is in
practice normally limited to 9,6 kbit/s.
5.1.2 Bit sequence
The ADPCM words comprised in each burst shall be transmitted in chronological order, and with the most significant
bit transmitted first within each word.
5.2 Other codings
No other coding scheme is permitted at this time. When introducing a new coding the following speech performance
characteristics shall be reviewed:
- frequency response;
- distortion;
- delay; and
- if the latter is widely affected, terminal coupling loss and network echo control.
6 Transmission aspects
6.1 Relative level
The digital line interface is a 0 dBr point according to ITU-T Recommendation G.101 [4]. As the various digital
transcoding algorithms are essentially loss-less, the relative level is constant over the whole digital path in the PP and
the FP.
6.2 Acoustic reference level
The acoustic reference level is defined as the acoustic level which corresponds to a level of -10 dBm0 at the digital
interface.
6.3 Volume control
Unless stated otherwise, if a user-controlled volume control is provided at the PP, the requirements apply for all
positions of the volume control, and the compliance tests shall be carried out at the maximum setting of this volume
control.
NOTE: The testing of a PP with a dual or an adaptive volume control requires further study.
7 Speech performance characteristics
7.1 PP frequency responses
7.1.1 Sending
The sending sensitivity-frequency response (from MRP to the digital interface) shall be within a mask as defined in
table 1.
ETSI
16 ETSI EN 300 175-8 V1.4.2 (1999-06)
Table 1: Sending sensitivity-frequency mask
Frequency (Hz) Upper limit (dB) Lower limit (dB)
100 - 9
200 0
300 0 - 14
800 0 -10
2 000 4 - 8
3 400 4 - 11
4 000 4
8 000 -13
NOTE 1: The limit at intermediate frequencies lies on a straight line drawn
between the given values on a log (frequency) - linear (dB) scale.
NOTE 2: All dB levels are on an arbitrary scale.
7.1.2 Receiving
The receiving sensitivity-frequency response (from the digital interface to the ERP) shall be within a mask as defined in
table 2.
Table 2: Receiving sensitivity-frequency mask
Frequency (Hz) Upper limit (dB) Lower limit (dB)
100 - 10
200 2
300 - 9
1 000 - 7
3 400 - 12
4 000 2
8 000 -152
NOTE 1: The limit at intermediate frequencies lies on a straight line drawn
between the given values on a log (frequency) - linear (dB) scale.
NOTE 2: All dB levels are on an arbitrary scale.
7.2 PP sending and receiving loudness ratings
7.2.1 Nominal values
The nominal values are:
- Sending Loudness Rating (SLR ) = 7 dB; and
H
- Receiving Loudness Rating (RLR ) = 3 dB.
H
There is a manufacturing tolerance of ± 3,5 dB on both RLR and SLR .
H H
NOTE: CCITT/ITU-T test methods on loudness ratings are valid only for codecs that can transmit sinusoids
without excessive distortion.
7.2.2 User-controlled volume control in PP
Two types of user-controlled volume control shall be permitted.
A user-controlled volume control shall be provided in all PP equipment, except where an adaptive volume control is
incorporated in the PP.
When adjusting the volume control from nominal to maximum setting, the decrease in RLR shall be not less than 6 dB.
H
ETSI
17 ETSI EN 300 175-8 V1.4.2 (1999-06)
Where user controlled volume control is provided instead of an adaptive volume control, adjust the volume control to
the setting (nominal) where the RLR is closest to its nominal value. At this setting the RLR and SLR shall
H H
simultaneously meet the values given in subclause 7.2.1, including the tolerances. A "joint acting" volume control is
where the PP can simultaneously change the values of SLR and RLR in opposite directions.
The RLR and SLR shall not exceed the limits given in tables 5 and 6.
H H
Table 3: Absolute limits for "joint-acting" volume control
Volume setting Maximum Minimum
RLR - 13 dB 19 dB
H
SLR 17 dB 3 dB
H
Table 4: Absolute limits for a receiving volume control
Volume setting Maximum Minimum
RLR - 13 dB 19 dB
H
NOTE 1: Minimum setting: The setting where the RLR has its maximum value.
Maximum setting: The setting where the RLR has its minimum value.
NOTE 2: A user-controlled volume control should include
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