SIST ETS 300 175-8:1999

SLOVENSKI STANDARD
01-julij-1999
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Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 8:
Speech coding and transmission
Ta slovenski standard je istoveten z: ETS 300 175-8 Edition 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.

EUROPEAN ETS 300 175-8
TELECOMMUNICATION September 1996
STANDARD Second Edition
Source: ETSI TC-RES Reference: RE/RES-03027-8
ICS: 33.060, 33.060.50
Key words: DECT, radio
Radio Equipment and Systems (RES);
Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI);
Part 8: Speech coding and transmission
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
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
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.

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ETS 300 175-8: September 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.

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ETS 300 175-8: September 1996
Contents
Foreword .7
1 Scope.9
2 Normative references.9
3 Definitions and abbreviations .11
3.1 Definitions.11
3.2 Abbreviations .12
4 Configurations .13
4.1 Reference configuration .13
4.1.1 Basic configuration.13
4.1.2 Portable Part (PP).14
4.1.2.1 Functional organization .14
4.1.2.2 Volume control.15
4.1.3 Fixed Part (FP).15
4.1.3.1 Digital interface.15
4.1.3.2 Analogue interface .16
4.1.3.3 FP adaptive volume control.16
4.2 Test configurations .16
5 Encoding.17
5.1 32 kbit/s full term (ADPCM).17
5.1.1 Algorithm .17
5.1.2 Bit sequence .17
5.2 Other codings .17
6 Transmission aspects .17
6.1 Relative level.17
6.2 Acoustic reference level.17
6.3 Volume control .17
7 Speech performance characteristics .18
7.1 PP frequency responses .18
7.1.1 Sending .18
7.1.2 Receiving.18
7.2 PP sending and receiving loudness ratings.18
7.2.1 Nominal values .18
7.2.2 User-controlled volume control in PP .19
7.2.3 PP adaptive volume control .19
7.2.4 FP adaptive volume control.20
7.3 Sidetone.20
7.3.1 Talker sidetone.20
7.3.2 Listener sidetone.20
7.4 Terminal coupling loss.21
7.4.1 Weighted Terminal Coupling Loss (TLCw) .21
7.4.1.1 PP for the 3,1 kHz service (PSTN or ISDN).21
7.4.1.2 FP with 4-wire interface.21
7.4.1.3 FP with analogue 2-wire interface .22
7.4.1.4 PP for unrestricted 64 kbit/s service .22
7.4.2 Stability loss.22
7.4.2.1 Requirement.22
7.4.2.2 Test conditions .22

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ETS 300 175-8: September 1996
7.4.2.3 Fixed geometry PP.22
7.4.2.4 Variable geometry PP .22
7.5 Distortion .23
7.5.1 Sending.23
7.5.2 Receiving .23
7.5.3 Sidetone .23
7.5.4 Recommended value for network planning .23
7.6 Out of band signals.23
7.6.1 Sending (discrimination against out of band input signals).23
7.6.2 Receiving (spurious out of band signals) .23
7.7 Noise.24
7.7.1 Sending.24
7.7.2 Narrow-band noise.24
7.7.3 Receiving .24
7.7.4 Level of sampling frequency (receiving) .24
7.8 Acoustic shock .24
7.8.1 Continuous signal.24
7.8.2 Peak signal .24
7.9 Delay.24
7.9.1 DECT network.24
7.9.2 PP.24
7.9.3 FP.24
7.10 Network echo control .25
7.11 PP ambient noise rejection .25
8 Additional features.26
8.1 Loudspeaking and hand-free facilities.26
8.2 Tandem with mobile radio network.26
8.2.1 Tandem with GSM.26
8.2.1.1 Network echo control.26
8.2.1.2 Terminal coupling loss .26
8.2.1.3 The GSM mobile transmitter operates in continuous mode .26
8.2.1.4 The GSM mobile transmitter operates in discontinuous
mode, DTX.26
8.3 DECT connected to the GSM fixed network.27
8.3.1 Network echo control .27
8.3.2 Terminal coupling loss.27
8.4 Wireless Relay Stations (WRS) .27
8.4.1 Modified FP network echo control requirements for implementation of 2
and 3 CRFP links in cascade .28
Annex A (informative): Description of "reference" echo control devices.29
A.1 Handset echo .29
A.1.1 Overview .29
A.1.1.1 Connection to the PSTN/ISDN.29
A.1.1.1.1 Local and national calls.29
A.1.1.1.2 Long distance connections with echo control devices in the
PSTN/ISDN, e.g. calls via satellites .29
A.1.1.2 Connection to the GSM network .30
A.1.2 Implementation of the FP echo control function subclause 7.4.1.2 b.30
A.1.2.1 Suppression threshold.30
A.1.2.2 Static characteristics of activation control .31
A.1.2.3 Dynamic characteristics of activation control .31
A.2 Network echo.31
A.2.1 Soft suppressor implementation of requirement 2 of subclause 7.10.32
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 of subclause 7.10.32

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ETS 300 175-8: September 1996
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
Annex E (informative): Bibliography.38
History .39

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ETS 300 175-8: September 1996
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ETS 300 175-8: September 1996
Foreword
This second edition European Telecommunication Standard (ETS) has been produced by the Radio
Equipment and Systems (RES) Technical Committee of the European Telecommunications Standards
Institute (ETSI).
This ETS forms part 8 of a series of 9 laying down the arrangements for the Digital Enhanced Cordless
Telecommunications (DECT) Common Interface (CI).
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".
Part 9: "Public Access Profile (PAP)".
Further details of the DECT system may be found in ETR 015, ETR 043, and ETR 056 (see annex E).
Transposition dates
Date of adoption of this ETS: 6 September 1996
Date of latest announcement of this ETS (doa): 31 December 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 June 1997
Date of withdrawal of any conflicting National Standard (dow): 30 June 1997

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ETS 300 175-8: September 1996
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ETS 300 175-8: September 1996
1 Scope
This second edition European Telecommunication Standard (ETS) is part of the Digital Enhanced Cordless
Telecommunications (DECT) Common Interface (CI) and 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.
This ETS 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 this ETS.
Tethered fixed point local loop applications are not required to comply with the requirements of this part.
The speech performance characteristics defined in this ETS typically conform to ETS 300 085 [19], 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 ETS 300 085 [19] 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 ETS 300 085 [19], 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, this ETS includes the basics on which the national specifications can be built, referring to
ETS 300 001 [20] (which specifies the connection of terminal equipments to the PSTN via a 2-wire
analogue interface) and the appropriate national standard.
ETSI/STC TM5 has prepared a technical report, ETR 041, 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 the supplementary services clause of ETR 056.
Information concerning test methods can be found in I-ETS 300 176 [9]. The test methods take into
account that DECT is a digital system.
2 Normative references
This ETS incorporates, by dated or undated reference, provisions from other publications. These normative
references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this ETS
only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies.
[1] ETS 300 175-1 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 1:
Overview".
[2] ETS 300 175-2 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 2: Physical
Layer (PHL)".
[3] ETS 300 175-3 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 3: Medium
Access Control (MAC) layer".
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ETS 300 175-8: September 1996
[4] ETS 300 175-4 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 4: Data
Link Control (DLC) layer".
[5] ETS 300 175-5 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 5: Network
(NWK) layer".
[6] ETS 300 175-6 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 6: Identities
and addressing".
[7] ETS 300 175-7 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 7: Security
features".
[8] ETS 300 444: "Radio Equipment and Systems (RES); Digital European Cordless
Telecommunications (DECT): Generic Access Profile (GAP)".
[9] I-ETS 300 176: "Radio Systems and Equipment (RES); Digital European
Cordless Telecommunications (DECT) Approval test specification".
[10] CCITT Recommendation G.101 (1988): "The transmission plan".
[11] CCITT Recommendation G.131 (1988): "Stability and echo".
[12] CCITT Recommendation G.164 (1988): "Echo suppressors".
[13] CCITT Recommendation G.165 (1988): "Echo cancellers".
[14] CCITT Recommendation G.701 (1988): "Vocabulary of digital transmission and
multiplexing, and pulse code modulation (PCM) terms".
[15] CCITT Recommendation G.726 (1991): "40, 32, 24, 16 kbit/s adaptive
differential pulse code modulation (ADPCM)".
[16] CCITT Recommendation I.241 (1988): "Teleservices supported by an ISDN".
[17] CCITT Recommendation P.10 (1988): "Vocabulary of terms on telephone
transmission quality and telephone sets".
[18] CCITT Recommendation P.34 (1988): "Transmission characteristics of
hands-free telephones".
[19] ETS 300 085: "Integrated Services Digital Network (ISDN): 3,1 kHz telephony
teleservice; Attachment requirements for handset terminals" (text relevant for
NET 33).
[20] ETS 300 001: "Attachments to Public Switched Telephone Network (PSTN);
General technical requirements for equipment connected to an analogue
subscriber interface in the PSTN" (Candidate NET 4).
[21] CCITT Recommendation G.113 (1988): "Transmission impairments".
[22] CCITT Recommendation G.111 (1988): "Loudness ratings (LRs) in an
international connection".
[23] 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)".

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ETS 300 175-8: September 1996
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
Central Control Fixed Part (CCFP): See ETS 300 175-1 [1].
Cordless Radio Fixed Part (CRFP): See ETS 300 175-1 [1].
DECT Network (DNW): See ETS 300 175-1 [1].
double duplex bearer : See ETS 300 175-1 [1].
End System (ES): See ETS 300 175-1 [1].
fixed geometry Portable Part (PP): A 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 ETS 300 175-1 [1].
Fixed radio Termination (FT): See ETS 300 175-1 [1].
Generic Access Profile (GAP): A standard in addition to the DECT CI that ensures interoperability
between FPs and PPs from different manufacturers.
handset echo: The 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 ETS 300 175-1 [1].
network echo: The 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 ETS 300 175-1 [1].
Portable Handset (PHS): See ETS 300 175-1 [1].
Portable Part (DECT Portable Part) (PP): See ETS 300 175-1 [1].
Portable radio Termination (PT): See ETS 300 175-1 [1].
public: See ETS 300 175-1 [1].
public access service: See ETS 300 175-1 [1].
Radio Fixed Part (RFP): See ETS 300 175-1 [1].
Repeater Part (REP) : See ETS 300 175-1 [1].
service provider (telecommunications service provider): See ETS 300 175-1 [1].
telephony service: See CCITT Recommendation I.241 [16].
user (of a telecommunication network): See ETS 300 175-1 [1].

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ETS 300 175-8: September 1996
variable geometry PP: A 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 ETS 300 175-1 [1].
3.2 Abbreviations
For the purposes of this ETS, relevant definitions and abbreviations in CCITT Recommendations P.10 [17]
and G.701 [14] apply. In addition the following abbreviations apply:
ADPCM Adaptive Differential Pulse Code Modulation
ARL Acoustic Reference Level
CCFP Central Control Fixed Part
CI Common Interface
CFRP Cordless Radio Fixed Part
CLRR Circuit Loudness Rating, Receiving
CLRS Circuit Loudness Rating, Sending
CODEC Coder-Decoder
CRFP Cordless Radio Fixed Part
CSPDN Circuit Switched Public Data Network
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 Termination
GAP Generic Access Profile
ISDN Integrated Services Digital Network
LE Local Echo
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
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
RLR Receiving Loudness Rating of the Handset
H
SLR Sending Loudness Rating of the Handset
H
TCLw weighted Terminal Coupling Loss
TELR Talker's Echo Loudness Rating
STMR Sidetone Masking Rating
QDU Quantization Distortion Unit
WRS Wireless Relay Station
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ETS 300 175-8: September 1996
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 (handset) FP (fixe d part)
Acoustic Air
in te rfa ce in te rfa ce L in e
Lin e
MR P
Acoustic in te rfa ce
Transcoder Transcoder
0 interface +
+ ec ho
Uniform Uniform
Volume control
PCM PC M
control +
to/from to/from
+ V o lu m e control
air code air code
coder +
]
co der
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 physically
accessible.
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ETS 300 175-8: September 1996
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 ETS 300 085 [19] 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 realises the adaptation to ETS 300 001 [20] and to national standards.
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:
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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
H H
interface and the uniform PCM reference point;
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c) the transcoder between uniform PCM and air-code.

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ETS 300 175-8: September 1996
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.
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:
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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.

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ETS 300 175-8: September 1996
4.1.3.2 Analogue interface
The organization of a FP with an analogue interface is shown in figure 4.
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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.
NOTE: Due to different transmission characteristics of the 2-wire local access in European
countries, it is recommended that careful attention is paid to the transmission
specification of the 2-wire FP interface, particularly in respect of transmission loss and
impedance.
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 I-ETS 300 176 [9]).

Page 17
ETS 300 175-8: September 1996
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 [15] for 32 kbit/s Adaptive
Differential Pulse Code Modulation (ADPCM).
The A-law companding and synchronous tandem adjustment may be omitted in FPs with an analogue line
interface and in PPs.
NOTE: CCITT Recommendation G.726 [15] 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 limited to 4,8 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 CCITT Recommendation G.101 [10]. 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.

Page 18
ETS 300 175-8: September 1996
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.
Table 1: Sending sensitivity-frequency mask
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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
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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.

Page 19
ETS 300 175-8: September 1996
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
H
less than 6dB.
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
H
SLR shall simultaneously meet the values given in subclause 7.2.1, including the tolerances. A "joint
H
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 an automatic reset function that ensures
that the default setting for each new call is no higher than the nominal setting.
NOTE3: Analogue networks generally require higher receive levels (lower RLR) than digital
networks (ISDN). This is to compensate for old long lossy analogue lines that still exist
in many PSTNs. This gives an interworking problem between analogue networks and
terminals that use digital codecs as in DECT systems and ISDN terminals. Most of the
calls do not have lossy lines, and then the receive signal becomes very high, which
could cause distortion in the A/D converters and also lower the margin for the wanted
terminal echo loss. The best solution is to adjust the general national requirements for
analogue terminals, so that 4 to 6 dB higher RLR is allowed when a DECT system is
the terminal of an analogue connection to the PSTN. This would not violate any national
planning rules, since each DECT PP has at least + 6 dB volume control to compensate
for any lossy connection. Some national administrations have already implemented this
principle.
7.2.3 PP adaptive volume control
The PP shall inform the FP if an adaptive volume control is implemented in the PP. Subclause 7.7.41 in
ETS 300 175-5 [5] describes how this shall be done.
This function is for further study and may follow GSM, or other, specifications when available.

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ETS 300 175-8: September 1996
7.2.4 FP adaptive volume control
An adaptive volume control, depending on the level of environmental noise at the PP, may be implemented
into the FP. The gain variation shall be symmetrical, i.e. the increase in the receiving direction shall be
equal to the decrease in the sending direction.
If the PP adaptive volume control feature is implemented then the FP adaptive volume control feature shall
be disabled.
NOTE 1: The PP ambient noise level is calculated in the FP based upon the minimum ambient
noise rejection requirement as specified in subclause 7.11.
NOTE 2: For an FP with an analogue interface, problems of saturation may occur depending on
national RLR values.
See annex D for further information.
7.3 Sidetone
7.3.1 Talker sidetone
The sidetone path shall be implemented
...