SIST ETS 300 395-3:1999

SLOVENSKI STANDARD
SIST ETS 300 395-3:1999
01-november-1999
Radijska oprema in sistemi (RES) - Vseevropski sistem snopovnega radia (TETRA)
- Prizemni snopovni radio (TETRA) - Govorni kodek za kanal s polno hitrostjo - 3.
del: Posebne obratovalne lastnosti
Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic channel; Part 3:
Specific operating features
Ta slovenski standard je istoveten z: ETS 300 395-3 Edition 1
ICS:
33.070.10 Prizemni snopovni radio Terrestrial Trunked Radio
(TETRA) (TETRA)
SIST ETS 300 395-3:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 395-3:1999

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SIST ETS 300 395-3:1999
EUROPEAN ETS 300 395-3
TELECOMMUNICATION May 1997
STANDARD
Source: ETSI TC-RES Reference: DE/RES-06002-3
ICS: 33.020
Key words: TETRA, CODEC
Radio Equipment and Systems (RES);
Trans-European Trunked Radio (TETRA);
Speech codec for full-rate traffic channel;
Part 3: Specific operating features
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 4 92 94 42 00 - Fax: +33 4 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

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ETS 300 395-3: May 1997
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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Contents
Foreword.5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .7
3.1 Definitions .7
3.2 Abbreviations .7
4 Speech encoder .8
4.1 Encoder homing function .9
4.1.1 Definition of encoder homing frame .9
4.1.2 Encoder homing .9
4.2 Speech importance function .9
4.3 Comfort noise function.9
4.4 Frame stealing function .9
4.5 Test mode functions .10
4.6 Encryption interface .10
5 Speech decoder .11
5.1 Encryption interface .11
5.2 Decoder homing function.12
5.2.1 Definition of decoder homing frame .12
5.2.2 Decoder homing.12
5.3 Missing frame generation .12
5.4 Missing frame substitution .12
5.5 Test mode functions .12
6 Signalling Data Block Format.13
Annex A (informative): Implementation of optional features .14
A.1 Speech importance calculation .14
A.2 Voice Activity Detection (VAD) .14
A.3 Discontinuous Transmission (DTX) .14
A.4 CNF computation .14
A.5 Missing Frame Generation (MFG) .14
A.5.1 Error concealment .14
A.5.2 Comfort noise generation .14
A.6 Setting BFI.15
A.7 U-plane frame stealing .15
A.8 Receiver muting .15
A.9 Response to U-plane signalling.15
History.16

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ETS 300 395-3: May 1997
Foreword
This European Telecommunication Standard (ETS) has been produced by the Radio Equipment System
(RES) Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS consists of four parts as follows:
Part 1: "General description of speech functions";
Part 2: "TETRA codec";
Part 3: "Specific operating features";
Part 4: "Codec conformance testing".
Transposition dates
Date of adoption: 2 May 1997
Date of latest announcement of this ETS (doa): 31 August 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 28 February 1998
Date of withdrawal of any conflicting National Standard (dow): 28 February 1998

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1 Scope
This European Telecommunication Standard (ETS) describes all the functions associated with the TETRA
speech codec, excepted the specification of the codec by itself which is entirely defined in
ETS 300 395-2 [2].
Clause 4 of this ETS provides a description of the functions associated with the speech encoder, while
clause 5 is its counterpart for the speech decoder.
Clause 6 describes the contents and the format of the signalling data block included in a stolen frame
when used for transferring information relevant to the codec in a U-plane signalling message.
In addition, annex A (informative) provides indications and preferred solutions for the implementation of
optional features.
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 300 395-1 (1995): "Radio Equipment and Systems (RES); Trans-European
Trunked Radio (TETRA) system; Speech codec for full-rate traffic channel;
Part 1: General description of speech functions".
[2] ETS 300 395-2 (1995): "Radio Equipment and Systems (RES); Trans-European
Trunked Radio (TETRA) system; Speech codec for full-rate traffic channel;
Part 2: TETRA codec".
[3] ETS 300 392-2 (1995): "Radio Equipment and Systems (RES); Trans-European
Trunked Radio (TETRA) system; Voice plus Data; Part 2: Air Interface".
[4] ETS 300 392-7 (1995): "Radio Equipment and Systems (RES); Trans-European
Trunked Radio (TETRA) system; Voice plus Data; Part 7: Security".
3 Definitions and abbreviations
3.1 Definitions
Refer to ETS 300 392-2 [3], clause 3 for common TETRA definitions.
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
BFI Bad Frame Indicator
CNF Comfort Noise Frame
DTX Discontinuous Transmission
LTP Long Term Predictor
MAC Medium Access Control
PCM Pulse Coded Modulation
RMS Root Mean Square
VAD Voice Activity Detector
Refer to ETS 300 392-2 [3] clause 3 for common TETRA abbreviations.

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4 Speech encoder
A diagram of the speech encoder and associated functions is given in figure 1. A more general overview is
given in ETS 300 395-1 [1]. The speech encoder is defined in ETS 300 395-2 [2] and the other functions
form the speech encoder control unit. The speech encoder control unit shall have access to all the internal
data and functions of the speech encoder (including the input speech).
1
SPEECH ENCODER
Reset
2
TEST MODE ENCODER HOMING
5
FUNCTIONS FUNCTION
FRAME STEALING COMFORT NOISE SPEECH IMPORTANCE
4
FUNCTION FUNCTION FUNCTION
ENCRYPTION
INTERFACE
Speech Encoder Control
3
1) 16-bit uniform PCM, 8 000 samples/s
2) Encoded speech frame 30 ms, 137 bits/frame
3) Encoded speech frame in "TMD_UNITDATA_request" message
4) Stolen indication in "TMD_REPORT_indication" message
5) Test mode control
Figure 1: Overview of speech encoder specific operating features
The speech encoder as defined in ETS 300 395-2 [2] shall receive speech in the form of 16-bit uniform PCM
at a rate of 8 000 samples per second.
The coded data corresponding to each 30 ms speech frame shall be output from the speech encoder control
unit via the encryption interface to the encryption unit (or directly to the MAC if encryption is not used). The
interfaces with the encryption unit, namely interface points 3 and 4 in figure 1, shall be as defined in
ETS 300 392-7 [4], clause 7. Message "TMD_UNITDATA_ request" is the means of conveying half-slots
from the U-plane to the MAC, while "TMD_REPORT_indication" enables the MAC to pass control information
to the U-plane.
Comfort noise parameters may be generated and their presence in the coded speech data shall be indicated
by a U-plane signalling message conveyed using the frame stealing mechanism.
A speech importance indication shall be provided.
The presence of a homing sequence in the input speech shall be recognized and the encoder reset to a
defined state.
All functions necessary to support conformance testing shall be implemented.

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An appropriate U_device destination address shall be set for each half slot of coded speech data to allow
correct routing at the receiver.
4.1 Encoder homing function
4.1.1 Definition of encoder homing frame
The encoder homing frame shall consist of 240 identical samples (corresponding to a 30 ms speech frame),
each 16 bits long with the value 0x0008.
NOTE: 0x0008 is a number represented in hexadecimal notation.
4.1.2 Encoder homing
Whenever the speech encoder receives at its input an encoder homing frame exactly aligned with its
internal speech frame segmentation, the following events shall take place:
Step 1: the speech encoder performs its normal operation and produces a speech parameter frame
at its output which is in general unknown;
Step 2: the speech encoder shall be reset and placed in its home state by executing the reset
functions "Init_Coder_Tetra( )" and "Init_Pre_Process( )" as defined in ETS 300 395-2 [2];
Step 3: the speech encoder is now in its home state and any further consecutive encoder homing
frames shall result in an output speech parameter frame identical to the decoder homing
frame.
Applying a sequence of N encoder homing frames to the speech encoder input shall cause at least N-1
decoder homing frames at the output of the speech encoder control unit.
4.2 Speech imp
...