EUROPEAN
`TELECOMMUNICATION
`STANDARD
`
`ETS 300 961
`
`May 1997
`
`Source: ETSI TC-SMG
`
`Reference: DE/SMG-110610Q
`
`ICS: 33.020
`
`Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
`
`GLOBAL SYSTEM FOR
`MOBILE COMMUNICATIONS
`
`R
`
`Digital cellular telecommunications system;
`Full rate speech;
`Transcoding
`(GSM 06.10 version 5.0.1)
`
`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.
`
`Ex. 1034 / Page 1 of 56
`Apple v. Saint Lawrence
`
`

`

`Page 2
`ETS 300 961 (GSM 06.10 version 5.0.1): 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.
`
`Ex. 1034 / Page 2 of 56
`
`

`

`Page 3
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`Contents
`
`Foreword .......................................................................................................................................................5
`
`1
`
`2
`
`3
`
`4
`
`Scope ..................................................................................................................................................7
`1.1
`Normative references ..........................................................................................................7
`1.1.1
`Abbreviations...................................................................................................8
`Outline description ...............................................................................................................8
`Functional description of audio parts ...................................................................................8
`PCM Format conversion ......................................................................................................9
`Principles of the RPE-LTP encoder .....................................................................................9
`Principles of the RPE-LTP decoder .....................................................................................9
`Sequence and subjective importance of encoded parameters..........................................10
`
`1.2
`1.3
`1.4
`1.5
`1.6
`1.7
`
`Transmission characteristics.............................................................................................................12
`2.1
`Performance characteristics of the analogue/digital interfaces .........................................12
`2.2
`Transcoder delay ...............................................................................................................12
`
`Functional description of the RPE-LTP codec ..................................................................................13
`3.1
`Functional description of the RPE-LTP encoder................................................................13
`3.1.1
`Offset compensation .....................................................................................13
`3.1.2
`Pre-emphasis ................................................................................................13
`3.1.3
`Segmentation ................................................................................................14
`3.1.4
`Autocorrelation ..............................................................................................14
`3.1.5
`Schur Recursion............................................................................................14
`3.1.6
`Transformation of reflection coefficients to Log.-Area Ratios .......................14
`3.1.7
`Quantization and coding of Log.-Area Ratios................................................15
`3.1.8
`Decoding of the quantized Log.-Area Ratios.................................................15
`3.1.9
`Interpolation of Log.-Area Ratios...................................................................15
`3.1.10
`Transformation of Log.-Area Ratios into reflection coefficients ....................15
`3.1.11
`Short term analysis filtering ...........................................................................16
`3.1.12
`Sub-segmentation .........................................................................................16
`3.1.13
`Calculation of the LTP parameters................................................................16
`3.1.14
`Coding/Decoding of the LTP lags..................................................................17
`3.1.15
`Coding/Decoding of the LTP gains................................................................17
`3.1.16
`Long term analysis filtering............................................................................17
`3.1.17
`Long term synthesis filtering..........................................................................18
`3.1.18
`Weighting Filter .............................................................................................18
`3.1.19
`Adaptive sample rate decimation by RPE grid selection...............................18
`3.1.20
`APCM quantization of the selected RPE sequence ......................................18
`3.1.21
`APCM inverse quantization ...........................................................................20
`3.1.22
`RPE grid positioning......................................................................................20
`Decoder .............................................................................................................................20
`3.2.1
`RPE decoding section ...................................................................................20
`3.2.2
`Long Term Prediction section .......................................................................20
`3.2.3
`Short term synthesis filtering section.............................................................20
`3.2.4
`Post-processing.............................................................................................20
`
`3.2
`
`Computational details of the RPE-LTP codec...................................................................................25
`4.1
`Data representation and arithmetic operations..................................................................25
`4.2
`Fixed point implementation of the RPE-LTP coder............................................................27
`4.2.0
`Scaling of the input variable ..........................................................................27
`4.2.1
`Downscaling of the input signal.....................................................................27
`4.2.2
`Offset compensation .....................................................................................27
`4.2.3
`Pre-emphasis ................................................................................................28
`4.2.4
`Autocorrelation ..............................................................................................28
`4.2.5
`Computation of the reflection coefficients .....................................................29
`4.2.6
`Transformation of reflection coefficients to Log.-Area Ratios .......................30
`4.2.7
`Quantization and coding of the Log.-Area Ratios..........................................30
`4.2.8
`Decoding of the coded Log.-Area Ratios ......................................................31
`
`Ex. 1034 / Page 3 of 56
`
`

`

`Page 4
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`4.2.9
`
`Computation of the quantized reflection coefficients .................................... 31
`4.2.9.1
`Interpolation of the LARpp[1..8] to get the LARp[1..8] ........ 31
`4.2.9.2
`Computation of the rp[1..8] from the interpolated
`LARp[1..8] ........................................................................... 32
`Short term analysis filtering .......................................................................... 32
`4.2.10
`Calculation of the LTP parameters ............................................................... 32
`4.2.11
`Long term analysis filtering ........................................................................... 34
`4.2.12
`Weighting filter.............................................................................................. 34
`4.2.13
`RPE grid selection ........................................................................................ 35
`4.2.14
`APCM quantization of the selected RPE sequence...................................... 35
`4.2.15
`APCM inverse quantization........................................................................... 36
`4.2.16
`RPE grid positioning ..................................................................................... 36
`4.2.17
`Update of the reconstructed short term residual signal dp[-120..-1]............. 37
`4.2.18
`Fixed point implementation of the RPE-LTP decoder....................................................... 37
`4.3.1
`RPE decoding section .................................................................................. 37
`4.3.2
`Long term synthesis filtering ......................................................................... 37
`4.3.3
`Computation of the decoded reflection coefficients...................................... 38
`4.3.4
`Short term synthesis filtering section ............................................................ 38
`4.3.5
`De-emphasis filtering.................................................................................... 39
`4.3.6
`Upscaling of the output signal....................................................................... 39
`4.3.7
`Truncation of the output variable .................................................................. 39
`Tables used in the fixed point implementation of the RPE-LTP coder and decoder......... 39
`
`4.3
`
`4.4
`
`5
`
`Digital test sequences....................................................................................................................... 41
`5.1
`Input and output signals .................................................................................................... 41
`5.2
`Configuration for the application of the test sequences .................................................... 42
`5.2.1
`Configuration 1 (encoder only) ..................................................................... 42
`5.2.2
`Configuration 2 (Decoder only)..................................................................... 42
`Test sequences................................................................................................................. 42
`5.3.1
`Test sequences for configuration 1 .............................................................. 42
`5.3.2
`Test sequences for configuration 2 .............................................................. 43
`
`5.3
`
`Annex A1 (informative): Codec performance ........................................................................................... 47
`
`A.1
`
`A.1.2.2.2
`A.1.2.2.3
`
`Performance of the RPE-LTP........................................................................................................... 47
`A.1.1
`Introduction........................................................................................................................ 47
`A.1.2
`Speech performance......................................................................................................... 47
`A.1.2.1
`Single encoding ............................................................................................ 47
`A.1.2.2
`Speech performance when interconnected with coding systems on an
`analogue basis.............................................................................................. 48
`A.1.2.2.1
`Performance with 32 kbit/s ADPCM (G.721, superseded
`by G.726) ............................................................................ 48
`Performance with another RPE-LTP codec........................ 48
`Performance with encoding other than RPE-LTP and 32
`kbit/s ADPCM (G.721, superseded by G.726) .................... 48
`Non-speech performance.................................................................................................. 48
`A.1.3.1
`Performance with single sine waves............................................................. 48
`A.1.3.2
`Performance with DTMF tones..................................................................... 48
`A.1.3.3
`Performance with information tones ............................................................. 49
`A.1.3.4
`Performance with voice-band data ............................................................... 49
`Delay ................................................................................................................................. 49
`Bibliography....................................................................................................................... 51
`
`A.1.3
`
`A.1.4
`A.1.5
`
`Annex A2 (informative): Subjective relevance of the speech coder output bits ....................................... 52
`
`Annex A3 (informative): Format for test sequence distribution ................................................................ 54
`A.3.1
`Type of files provided ........................................................................................................ 54
`A.3.2
`File format description....................................................................................................... 54
`
`Annex B (informative):
`
`Test sequence diskette...................................................................................... 55
`
`History ......................................................................................................................................................... 56
`
`Ex. 1034 / Page 4 of 56
`
`

`

`Page 5
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`Foreword
`
`This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
`(SMG) Technical Committee (TC) of the European Telecommunications Standards Institute (ETSI).
`
`This ETS specifies the full rate speech transcoding within the digital cellular telecommunications system.
`
`This ETS is a GSM technical specification version 5. The ETS from which this ETS has evolved is GSM
`Phase 2 ETS 300 580-2 (GSM 06.10 version 4.0.2).
`
`NOTE:
`
`This ETS is a reproduction of recommendation T/L/03/11 "13 kbit/s Regular Pulse
`Excitation - Long Term Prediction - Linear Predictive Coder for use in the digital
`cellular telecommunications system".
`
`A 3,5 inch diskette (annex B) is attached to the back cover of this ETS, the diskette contain test
`sequences, as described in clause 5.
`
`The diskette contain LHA compressed files and is labelled as follows:
`
`Diskette 1
`
`ETS 300 961, annex B: Test sequences for the GSM Full Rate speech codec;
`Test sequences SEQ01.xxx to SEQ05.xxx.
`
`The specification from which this ETS has been derived was originally based on CEPT documentation,
`hence the presentation of this ETS may not be entirely in accordance with the ETSI/PNE rules.
`
`Transposition dates
`
`Date of adoption:
`
`Date of latest announcement of this ETS (doa):
`
`Date of latest publication of new National Standard
`or endorsement of this ETS (dop/e):
`
`18 April 1997
`
`31 August 1997
`
`28 February 1998
`
`Date of withdrawal of any conflicting National Standard (dow):
`
`28 February 1998
`
`Ex. 1034 / Page 5 of 56
`
`

`

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`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
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`
`Ex. 1034 / Page 6 of 56
`
`

`

`Page 7
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`1
`
`Scope
`
`The transcoding procedure specified in this European Telecommunication Standard (ETS) is applicable
`for the full-rate Traffic Channel (TCH) in the digital cellular telecommunications system. The use of this
`transcoding scheme for other applications has not been considered.
`
`In GSM 06.01, a reference configuration for the speech transmission chain of the digital cellular
`telecommunications system is shown. According to this reference configuration, the speech encoder takes
`its input as a 13 bit uniform PCM signal either from the audio part of the mobile station or on the network
`side, from the PSTN via an 8 bit/A-law to 13 bit uniform PCM conversion. The encoded speech at the
`output of the speech encoder is delivered to a channel encoder unit which is specified in GSM 05.03. In
`the receive direction, the inverse operations take place.
`
`This ETS describes the detailed mapping between input blocks of 160 speech samples in 13 bit uniform
`PCM format to encoded blocks of 260 bits and from encoded blocks of 260 bits to output blocks of
`160 reconstructed speech samples. The sampling rate is 8000 sample/s leading to an average bit rate for
`the encoded bit stream of 13 kbit/s. The coding scheme is the so-called Regular Pulse Excitation - Long
`Term prediction - Linear Predictive Coder, here-after referred to as RPE-LTP.
`
`This ETS also specifies the conversion between A-law PCM and 13 bit uniform PCM. Performance
`requirements for the audio input and output parts are included only to the extent that they affect the
`transcoder performance. The ETS also describes the codec down to the bit level, thus enabling the
`verification of compliance to the ETS to a high degree of confidence by use of a set of digital test
`sequences. These test sequences are described and are included in this ETS on diskette.
`
`1.1
`
`Normative references
`
`This ETS incorporates by dated and 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]
`
`[2]
`
`[3]
`
`[4]
`
`[5]
`
`[6]
`
`[7]
`
`[8]
`
`[9]
`
`GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+);
`Abbreviations and acronyms".
`
`(ETS 300 909):
`GSM 05.03
`(Phase 2+); Channel coding".
`
`"Digital cellular
`
`telecommunications system
`
`GSM 06.01 (ETS 300 960): "Digital cellular telecommunications system; Full
`rate speech; Processing functions".
`
`telecommunications system
`"Digital cellular
`(ETS 300 607):
`GSM 11.10
`(Phase 2); Mobile Station (MS) conformity specification".
`
`ETS 300 085: "Integrated Services Digital Network (ISDN); 3,1kHz telephony
`teleservice; Attachment
`requirements
`for handset
`terminals
`(Candidate
`NET 33)".
`
`ITU-T Recommendation G.711: "Pulse code modulation (PCM) of voice
`frequencies".
`
`ITU-T Recommendation G.712: "Transmission performance characteristics of
`pulse code modulation".
`
`ITU-T Recommendation G.726: "40, 32, 24, 16 kbit/s adaptive differential pulse
`code modulation (ADPCM)".
`
`ITU-T Recommendation Q.35: "Technical characteristics of
`telephone service".
`
`tones
`
`for
`
`the
`
`Ex. 1034 / Page 7 of 56
`
`

`

`Page 8
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`[10]
`
`[11]
`
`ITU-T Recommendation V.21: "300 bits per second duplex modem standardized
`for use in the general switched telephone network".
`
`ITU-T Recommendation V.23: "600/1 200-band modem standardized for use in
`the general switched telephone network".
`
`1.1.1
`
`Abbreviations
`
`Abbreviations used in this ETS are listed in GSM 01.04.
`
`1.2
`
`Outline description
`
`The ETS is structured as follows:
`
`Subclause 1.3 contains a functional description of the audio parts including the A/D and D/A functions.
`Subclause 1.4 describes the conversion between 13 bit uniform and 8 bit A-law samples. Subclauses 1.5
`and 1.6 present a simplified description of the principles of the RPE-LTP encoding and decoding process
`respectively. In subclause 1.7, the sequence and subjective importance of encoded parameters are given.
`
`Clause 2 deals with the transmission characteristics of the audio parts that are relevant for the
`performance of the RPE-LTP codec.
`
`Some transmission characteristics of the RPE-LTP codec are also specified in clause 2. Clause 3
`presents the functional description of the RPE-LTP coding and decoding procedures, whereas clause 4
`describes the computational details of the algorithm. Procedures for the verification of the correct
`functioning of the RPE-LTP are described in clause 5.
`
`Performance and network aspects of the RPE-LTP codec are contained in annex A1.
`
`1.3
`
`Functional description of audio parts
`
`The analogue-to-digital and digital-to-analogue conversion will in principle comprise the following
`elements:
`
`1)
`
`Analogue to uniform digital:
`
`-
`-
`-
`-
`-
`
`microphone;
`input level adjustment device;
`input anti-aliasing filter;
`sample-hold device sampling at 8 kHz;
`analogue-to-uniform digital conversion to 13 bits representation.
`
`The uniform format shall be represented in two's complement.
`
`2)
`
`Uniform digital to analogue:
`
`-
`-
`-
`-
`-
`
`conversion from 13 bit /8 kHz uniform PCM to analogue;
`a hold device;
`reconstruction filter including x/sin x correction;
`output level adjustment device;
`earphone or loudspeaker.
`
`In the terminal equipment, the A/D function may be achieved either:
`
`-
`
`-
`
`by direct conversion to 13 bit uniform PCM format;
`
`or by conversion to 8 bit/A-law companded format, based on a standard A-law codec/filter
`according to ITU-T Recommendation G.711/714, followed by the 8-bit to 13-bit conversion
`according to the procedure specified in subclause 1.4.
`
`For the D/A operation, the inverse operations take place.
`
`Ex. 1034 / Page 8 of 56
`
`

`

`Page 9
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`In the latter case it should be noted that the specifications in ITU-T recommendation G.714 (superseded
`by G.712) are concerned with PCM equipment located in the central parts of the network. When used in
`the terminal equipment, this specification does not on its own ensure sufficient out-of-band attenuation.
`
`The specification of out-of-band signals is defined in section 2 between the acoustic signal and the digital
`interface to take into account that the filtering in the terminal can be achieved both by electronic and
`acoustical design.
`
`1.4
`
`PCM Format conversion
`
`The conversion between 8 bit A-law companded format and the 13-bit uniform format shall be as defined
`in ITU-T Recommendation G.721 (superseded by G.726), subclause 4.2.1, sub-block EXPAND and
`subclause 4.2.7, sub-block COMPRESS. The parameter LAW = 1 should be used.
`
`1.5
`
`Principles of the RPE-LTP encoder
`
`A simplified block diagram of the RPE-LTP encoder is shown in figure 1.1. In this diagram the coding and
`quantization functions are not shown explicitly.
`
`The input speech frame, consisting of 160 signal samples (uniform 13 bit PCM samples), is first
`pre-processed to produce an offset-free signal, which is then subjected to a first order pre-emphasis filter.
`The 160 samples obtained are then analysed to determine the coefficients for the short term analysis filter
`(LPC analysis). These parameters are then used for the filtering of the same 160 samples. The result is
`160 samples of the short term residual signal. The filter parameters, termed reflection coefficients, are
`transformed to log.area ratios, LARs, before transmission.
`
`For the following operations, the speech frame is divided into 4 sub-frames with 40 samples of the short
`term residual signal in each. Each sub-frame is processed blockwise by the subsequent functional
`elements.
`
`Before the processing of each sub-block of 40 short term residual samples, the parameters of the long
`term analysis filter, the LTP lag and the LTP gain, are estimated and updated in the LTP analysis block,
`on the basis of the current sub-block of the present and a stored sequence of the 120 previous
`reconstructed short term residual samples.
`
`A block of 40 long term residual signal samples is obtained by subtracting 40 estimates of the short term
`residual signal from the short term residual signal itself. The resulting block of 40 long term residual
`samples is fed to the Regular Pulse Excitation analysis which performs the basic compression function of
`the algorithm.
`
`As a result of the RPE-analysis, the block of 40 input long term residual samples are represented by one
`of 4 candidate sub-sequences of 13 pulses each. The subsequence selected is identified by the RPE grid
`position (M). The 13 RPE pulses are encoded using Adaptive Pulse Code Modulation (APCM) with
`estimation of the sub-block amplitude which is transmitted to the decoder as side information.
`
`The RPE parameters are also fed to a local RPE decoding and reconstruction module which produces a
`block of 40 samples of the quantized version of the long term residual signal.
`
`By adding these 40 quantized samples of the long term residual to the previous block of short term
`residual signal estimates, a reconstructed version of the current short term residual signal is obtained.
`
`The block of reconstructed short term residual signal samples is then fed to the long term analysis filter
`which produces the new block of 40 short term residual signal estimates to be used for the next sub-block
`thereby completing the feedback loop.
`
`1.6
`
`Principles of the RPE-LTP decoder
`
`The simplified block diagram of the RPE-LTP decoder is shown in fig 1.2. The decoder includes the same
`structure as the feed-back loop of the encoder. In error-free transmission, the output of this stage will be
`the reconstructed short term residual samples. These samples are then applied to the short term
`synthesis filter followed by the de-emphasis filter resulting in the reconstructed speech signal samples.
`
`Ex. 1034 / Page 9 of 56
`
`

`

`Page 10
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`1.7
`
`Sequence and subjective importance of encoded parameters
`
`As indicated in fig 1.1 the three different groups of data are produced by the encoder are:
`
`-
`-
`-
`
`the short term filter parameters;
`the Long Term Prediction (LTP) parameters;
`the RPE parameters.
`
`The encoder will produce this information in a unique sequence and format, and the decoder shall receive
`the same information in the same way. In table 1.1, the sequence of output bits b1 to b260 and the bit
`allocation for each parameter is shown.
`
`The different parameters of the encoded speech and their individual bits have unequal importance with
`respect to subjective quality. Before being submitted to the channel encoding function the bits have to be
`rearranged in the sequence of importance as given in GSM 05.03. The ranking has been determined by
`subjective testing and the procedure used is described in annex A2.
`
`Table 1.1a: Encoder output parameters in order of occurrence and
`bit allocation within the speech frame of 260 bits/20 ms
`
`==================================================================
`Parameter Parameter Parameter Var. Number Bit no.
` number name name of bits (LSB-MSB)
`==================================================================
`
`==================================================================
` 1 LAR 1 6 b1 - b6
` 2 LAR 2 6 b7 - b12
`FILTER 3 Log. Area LAR 3 5 b13 - b17
` 4 ratios LAR 4 5 b18 - b22
`PARAMETERS 5 1 - 8 LAR 5 4 b23 - b26
` 6 LAR 6 4 b27 - b30
` 7 LAR 7 3 b31 - b33
` 8 LAR 8 3 b34 - b36
`==================================================================
`
`Sub-frame no.1
`
`==================================================================
`LTP 9 LTP lag N1 7 b37 - b43
`PARAMETERS 10 LTP gain b1 2 b44 - b45
`------------------------------------------------------------------
` 11 RPE grid position M1 2 b46 - b47
`RPE 12 Block amplitude Xmax1 6 b48 - b53
`PARAMETERS 13 RPE-pulse no.1 x1(0) 3 b54 - b56
` 14 RPE-pulse no.2 x1(1) 3 b57 - b59
` .. ... ...
` 25 RPE-pulse no.13 x1(12) 3 b90 - b92
`==================================================================
`
`Sub-frame no.2
`
`==================================================================
`LTP 26 LTP lag N2 7 b93 - b99
`PARAMETERS 27 LTP gain b2 2 b100- b101
`------------------------------------------------------------------
` 28 RPE grid position M2 2 b102- b103
`RPE 29 Block amplitude Xmax2 6 b104- b109
`PARAMETERS 30 RPE-pulse no.1 x2(0) 3 b110- b112
` 31 RPE-pulse no.2 x2(1) 3 b113- b115
` .. ... ...
` 42 RPE-pulse no.13 x2(12) 3 b146- b148
`==================================================================
`
`Ex. 1034 / Page 10 of 56
`
`

`

`Page 11
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`Table 1.1b: Encoder output parameters in order of occurrence and
`bit allocation within the speech frame of 260 bits/20 ms
`
`Sub-frame no.3
`
`==================================================================
`LTP 43 LTP lag N3 7 b149- b155
`PARAMETERS 44 LTP gain b3 2 b156- b157
`------------------------------------------------------------------
` 45 RPE grid position M3 2 b158- b159
`RPE 46 Block amplitude Xmax3 6 b160- b165
`PARAMETERS 47 RPE-pulse no.1 x3(0) 3 b166- b168
` 48 RPE-pulse no.2 x3(1) 3 b169- b171
` .. ... ...
` 59 RPE-pulse no.13 x3(12) 3 b202- b204
`==================================================================
`
`Sub-frame no.4
`
`==================================================================
`LTP 60 LTP lag N4 7 b205- b211
`PARAMETERS 61 LTP gain b4 2 b212- b213
`------------------------------------------------------------------
` 62 RPE grid position M4 2 b214- b215
`RPE 63 Block amplitude Xmax4 6 b216- b221
`PARAMETERS 64 RPE-pulse no.1 x4(0) 3 b222- b224
` 65 RPE-pulse no.2 x4(1) 3 b225- b227
` .. ... ...
` 76 RPE-pulse no.13 x4(12) 3 b258- b260
`==================================================================
`
`Input
`
`signal
`
`Pre-
`processing
`
`Short term
`LPC
`analysis
`
`Short term
`analysis
`filter
`
`(1)
`
`+
`
`(2)
`
`-
`(3)
`
`RPE grid
`selection
`and coding
`
`Reflection
`coefficients coded as
`Log. - Area Ratios
`(36 bits/20 ms)
`
`RPE parameters
`(47 bits/5 ms)
`
`Long term
`analysis
`filter
`
`(4)
`
`+
`
`(5)
`
`RPE grid
`decoding and
`positioning
`
`LTP
`analysis
`
`LTP parameters
`(9 bits/5 ms)
`
`(1) Short term residual
`(2) Long term residual (40 samples)
`(3) Short term residual estimate (40 samples)
`(4) Reconstructed short term residual (40 samples)
`(5) Quantized long term residual (40 samples)
`
`To
`
`radio
`
`subsystem
`
`Figure 1.1: Simplified block diagram of the RPE - LPT encoder
`
`Ex. 1034 / Page 11 of 56
`
`

`

`Page 12
`ETS 300 961 (GSM 06.10 version 5.0.1): May 1997
`
`Reflection coefficients coded
`as Log. - Area Ratios
`(36 bits/20 ms)
`
`RPE grid
`decoding and
`positioning
`
`RPE
`parameters
`(47 bits/5 ms)
`
`+
`
`Long term
`synthesis
`filter
`
`Short term
`synthesis
`filter
`
`Post-
`processing
`
`Output
`signal
`
`LTP
`parameters
`(9 bits/5 ms)
`
`From
`
`radio
`
`subsystem
`
`Figure 1.2: Simplified block diagram of the RPE - LTP decoder
`
`2
`
`Transmission characteristics
`
`This section specifies the necessary performance characteristics of the audio parts for proper functioning
`of the speech transcoder. Some transmission performance characteristics of the RPE-LTP transcoder are
`also given to assist the designer of the speech transcoder function. The information given here is
`redundant and the detailed specifications are contained in recommendation GSM 11.10.
`
`The performance characteristics are referred to the 13 bit uniform PCM interface.
`
`NOTE:
`
`To simplify the verification of the specifications, the performance limits may be referred
`to an A-law measurement interface according to ITU-T Recommendation G.711. In
`this way, standard measuring equipments for PCM sys