SIST ETS 300 395-3:1999

• Abstract:

  Selection and specification of the speech codec for TETRA voice plus data standard

• Status: Published
• Publication Date: 31-Oct-1999
• ICS: 33.070.10 - Terrestrial Trunked Radio (TETRA)
• Technical Committee: RES - Radio equipment and systems
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Nov-1999
• Due Date: 01-Nov-1999
• Completion Date: 01-Nov-1999
• Mandate: T-300
• Ref Project: ETSI ETS 300 395-3 ed.1 (1997-05) - Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic channel; Part 3: Specific operating features

Overview

SIST ETS 300 395-3:1999 defines the specific operating features of the speech codec for the full-rate traffic channel used in the Terrestrial Trunked Radio (TETRA) standard. Developed by the Slovenski inštitut za standardizacijo (SIST), this standard supports high-quality voice communication and data transmission in TETRA radio systems. It covers the practical implementation and handling of speech codec operations, complementing the technical codec specifications defined in ETS 300 395-2.

This part of the standard addresses key encoder and decoder functions, handling of comfort noise, frame loss, signalling, and test modes. It is intended for radio equipment developers, system integrators, and professionals working with TETRA-based communications, ensuring interoperability and optimized speech transmission across diverse operational environments.

Key Topics

• Speech Codec Control

  • Management of input and output speech frames for reliable conversion to and from digital format.
  • Functions for homing (resetting) the encoder and decoder to ensure synchronization and consistent behavior.

• Comfort Noise Generation

  • Support for comfort noise frames (CNF) to maintain voice channel quality during transmission gaps or Discontinuous Transmission (DTX).
  • Calculation and transmission of comfort noise parameters to avoid abrupt silences.

• Speech Frame Importance

  • Assignment of importance levels to speech frames, minimizing the impact of frame stealing on overall speech quality.
  • Optional implementation guidance for linking frame importance to speech energy levels.

• Frame Handling: Stealing, Substitution, and Error Concealment

  • Mechanisms for "frame stealing," allowing signalling to share bandwidth with user data while managing impact on voice quality.
  • Substitution and error concealment techniques to handle missing or corrupted frames, including comfort noise insertion.

• Signalling Data Blocks

  • Handling and encoding of U-plane (user plane) signalling messages such as SPEECH_ON, SPEECH_OFF, CNF_COMMAND, and MUTE.
  • Integration with TETRA’s air interface and encryption systems.

• Test Mode Functions

  • Support for codec conformance testing by disabling specific features and ensuring repeatable test conditions.

Applications

• Public Safety and Emergency Communications

  • Ensures robust and clear voice communication for police, firefighters, and emergency medical services using TETRA radio systems.
  • Maintains call quality during poor signal conditions or network congestion via adaptive noise and error management.

• Transportation and Utility Services

  • Enhances operational coordination in sectors like railways, airports, and energy distribution by providing reliable group communication and data over radio.

• Critical Infrastructure and Industrial Use

  • Supports secure, interference-resistant communications in sectors requiring high levels of reliability, security, and interoperability.

• Equipment Design and Certification

  • Guides manufacturers in implementing compliant TETRA speech codec features, facilitating device certification and interoperability.

Related Standards

• ETS 300 395-1: General description of TETRA speech functions.
• ETS 300 395-2: Specifies the TETRA codec algorithm and technical parameters.
• ETS 300 392-2: TETRA Voice plus Data - Air Interface; foundational for physical and data link layer integration.
• ETS 300 392-7: TETRA Voice plus Data - Security aspects, including encryption interface requirements.

By referencing and applying SIST ETS 300 395-3:1999, organizations deploying TETRA systems can ensure optimal speech codec performance, seamless interoperability, and adherence to recognized European telecommunication standards for mission-critical communications.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.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 lastnostiTerrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic channel; Part 3: Specific operating features33.070.10Prizemni snopovni radio (TETRA)Terrestrial Trunked Radio (TETRA)33.020Telekomunikacije na splošnoTelecommunications in generalICS:Ta slovenski standard je istoveten z:ETS 300 395-3 E13SIST ETS 300 395-3:1999en01-MXOLM19993SIST ETS 300 395-3:1999SLOVENSKI
STANDARD
EUROPEANETS 300 395-3TELECOMMUNICATIONMay 1997STANDARDSource: ETSI TC-RESReference: DE/RES-06002-3ICS:33.020Key words:TETRA, CODECRadio Equipment and Systems (RES);Trans-European Trunked Radio (TETRA);Speech codec for full-rate traffic channel;Part 3: Specific operating featuresETSIEuropean Telecommunications Standards InstituteETSI SecretariatPostal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail].: [phone] - Fax: [phone]Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1997. All rights reserved.SIST ETS 300 395-3:1999

Page 2ETS 300 395-3: May 1997Whilst 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.SIST ETS 300 395-3:1999

Page 3ETS 300 395-3: May 1997ContentsForeword.51Scope.72Normative references.73Definitions and abbreviations.73.1Definitions.73.2Abbreviations.74Speech encoder.84.1Encoder homing function.94.1.1Definition of encoder homing frame.94.1.2Encoder homing.94.2Speech importance function.94.3Comfort noise function.94.4Frame stealing function.94.5Test mode functions.104.6Encryption interface.105Speech decoder.115.1Encryption interface.115.2Decoder homing function.125.2.1Definition of decoder homing frame.125.2.2Decoder homing.125.3Missing frame generation.125.4Missing frame substitution.125.5Test mode functions.126Signalling Data Block Format.13Annex A (informative):Implementation of optional features.14A.1Speech importance calculation.14A.2Voice Activity Detection (VAD).14A.3Discontinuous Transmission (DTX).14A.4CNF computation.14A.5Missing Frame Generation (MFG).14A.5.1Error concealment.14A.5.2Comfort noise generation.14A.6Setting BFI.15A.7U-plane frame stealing.15A.8Receiver muting.15A.9Response to U-plane signalling.15History.16SIST ETS 300 395-3:1999

Page 4ETS 300 395-3: May 1997Blank pageSIST ETS 300 395-3:1999

Page 5ETS 300 395-3: May 1997ForewordThis 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 datesDate of adoption:2 May 1997Date of latest announcement of this ETS (doa):31 August 1997Date of latest publication of new National Standardor endorsement of this ETS (dop/e):28 February 1998Date of withdrawal of any conflicting National Standard (dow):28 February 1998SIST ETS 300 395-3:1999

Page 6ETS 300 395-3: May 1997Blank pageSIST ETS 300 395-3:1999

Page 7ETS 300 395-3: May 19971ScopeThis European Telecommunication Standard (ETS) describes all the functions associated with the TETRAspeech codec, excepted the specification of the codec by itself which is entirely defined inETS 300 395-2 [2].Clause 4 of this ETS provides a description of the functions associated with the speech encoder, whileclause 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 framewhen 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 ofoptional features.2Normative referencesThis ETS incorporates, by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listedhereafter. For dated references, subsequent amendments to, or revisions of, any of these publicationsapply to this ETS only when incorporated in it by amendment or revision. For undated references the latestedition of the publication referred to applies.[1]ETS 300 395-1 (1995): "Radio Equipment and Systems (RES); Trans-EuropeanTrunked 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-EuropeanTrunked 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-EuropeanTrunked Radio (TETRA) system; Voice plus Data; Part 2: Air Interface".[4]ETS 300 392-7 (1995): "Radio Equipment and Systems (RES); Trans-EuropeanTrunked Radio (TETRA) system; Voice plus Data; Part 7: Security".3Definitions and abbreviations3.1DefinitionsRefer to ETS 300 392-2 [3], clause 3 for common TETRA definitions.3.2AbbreviationsFor the purposes of this ETS, the following abbreviations apply:BFIBad Frame IndicatorCNFComfort Noise FrameDTXDiscontinuous TransmissionLTPLong Term PredictorMACMedium Access ControlPCMPulse Coded ModulationRMSRoot Mean SquareVADVoice Activity DetectorRefer to ETS 300 392-2 [3] clause 3 for common TETRA abbreviations.SIST ETS 300 395-3:1999

Page 8ETS 300 395-3: May 19974Speech encoderA diagram of the speech encoder and associated functions is given in figure 1. A more general overview isgiven in ETS 300 395-1 [1]. The speech encoder is defined in ETS 300 395-2 [2] and the other functionsform the speech encoder control unit. The speech encoder control unit shall have access to all the internaldata and functions of the speech encoder (including the input speech).COMFORT NOISEFUNCTIONTEST MODEFUNCTIONS1235Reset4ENCODER HOMINGFUNCTIONSPEECH IMPORTANCEFUNCTIONSpeech Encoder ControlFRAME STEALINGFUNCTIONENCRYPTIONINTERFACESPEECH ENCODER1)16-bit uniform PCM, 8 000 samples/s2)Encoded speech frame 30 ms, 137 bits/frame3)Encoded speech frame in "TMD_UNITDATA_request" message4)Stolen indication in "TMD_REPORT_indication" message5)Test mode controlFigure 1: Overview of speech encoder specific operating featuresThe speech encoder as defined in ETS 300 395-2 [2] shall receive speech in the form of 16-bit uniform PCMat 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 controlunit via the encryption interface to the encryption unit (or directly to the MAC if encryption is not used). Theinterfaces with the encryption unit, namely interface points 3 and 4 in figure 1, shall be as defined inETS 300 392-7 [4], clause 7. Message "TMD_UNITDATA_ request" is the means of conveying half-slotsfrom the U-plane to the MAC, while "TMD_REPORT_indication" enables the MAC to pass control informationto the U-plane.Comfort noise parameters may be generated and their presence in the coded speech data shall be indicatedby 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 adefined state.All functions necessary to support conformance testing shall be implemented.SIST ETS 300 395-3:1999

Page 9ETS 300 395-3: May 1997An appropriate U_device destination address shall be set for each half slot of coded speech data to allowcorrect routing at the receiver.4.1Encoder homing function4.1.1Definition of encoder homing frameThe 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.4.1.2Encoder homingWhenever the speech encoder receives at its input an encoder homing frame exactly aligned with itsinternal speech frame segmentation, the following events shall take place:Step 1:the speech encoder performs its normal operation and produces a speech parameter frameat its output which is in general unknown;Step 2:the speech encoder shall be reset and placed in its home state by executing the resetfunctions "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 homingframes shall result in an output speech parameter frame identical to the decoder homingframe.Applying a sequence of N encoder homing frames to the speech encoder input shall cause at least N-1decoder homing frames at the output of the speech encoder control unit.4.2Speech importance functionThis function shall compute a
...

SLOVENSKI STANDARD
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)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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: [e-mail]
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

Page 2
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.

Page 3
ETS 300 395-3: May 1997
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
Blank page
Page 5
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

Page 6
ETS 300 395-3: May 1997
Blank page
Page 7
ETS 300 395-3: May 1997
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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ETS 300 395-3: May 1997
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).
SPEECH ENCODER
Reset
TEST MODE ENCODER HOMING
FUNCTIONS FUNCTION
FRAME STEALING COMFORT NOISE SPEECH IMPORTANCE
FUNCTION FUNCTION FUNCTION
ENCRYPTION
INTERFACE
Speech Encoder Control
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.

Page 9
ETS 300 395-3: May 1997
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
...