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8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply:
ETS European Telecommunication Standard
GSM Global System for Mobile communications
For abbreviations not given in this clause, see GSM 01.04 [1]. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 4 General | Digital test sequences are necessary to test for a bit exact implementation of the half rate speech transcoder (GSM 06.20 [2]), Voice Activity Detector (GSM 06.42 [6]), comfort noise (GSM 06.22 [4]) and the discontinuous transmission (GSM 06.41 [5]).
The test sequences may also be used to verify installations of the AN... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 5 Test sequence format | This clause provides information on the format of the digital test sequences for the GSM half rate speech transcoder (GSM 06.20 [2]), Voice Activity Detector (GSM 06.42 [6]), comfort noise (GSM 06.22 [4]) and the discontinuous transmission (GSM 06.41 [5]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 5.1 File format | The test sequence files are provided in archive en_300968v080001p0.ZIP which accompanies the present document.
Following decompression, by execution of the 11 "disk*.exe" files, four types of file are provided:
‑ Files for input to the GSM half rate speech encoder: *.INP
‑ Files for comparison with the encoder output: ... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 5.2 Codec homing | Each *.INP file includes two homing frames at the start of the test sequence. The function of these frames is to reset the speech encoder state variables to their initial value. In the case of a correct installation of the ANSI‑C simulation (GSM 06.06 [7]), all speech encoder output frames shall be identical to the cor... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6 Speech codec test sequences | This clause describes the test sequences designed to exercise the GSM half rate speech transcoder (GSM 06.20 [2]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.1 Codec configuration | The speech encoder shall be configured to operate in the non‑DTX mode. The VAD and SP flags shall be set to 1 at the speech encoder output. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2 Speech codec test sequences | Table 5 lists the location and size of the speech codec test sequences. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2.1 Speech encoder test sequences | Three encoder input sequences are provided:
‑ SEQ01.INP ‑ Sequence for exercising the LPC vector quantization codebooks;
‑ SEQ02.INP ‑ Sequence for exercising the long term predictor codebooks;
‑ SEQ03.INP ‑ Sequence for exercising the remaining excitation codebooks.
The SEQ01.INP sequence causes the GSM half rate spee... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2.2 Speech decoder test sequences | Four speech decoder input sequences are provided:
‑ SEQ01.DEC;
‑ SEQ02.DEC;
‑ SEQ03.DEC;
‑ SEQ04.DEC.
The SEQ01.DEC, SEQ02.DEC, and SEQ03.DEC sequences test the operation of the GSM half rate speech decoder in the absence of channel errors. They are derived from the corresponding SEQXX.INP sequences. In a correct imple... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2.3 Codec homing sequence | In addition to the test sequences described above, two homing sequences are provided to assist in codec type approval testing. SEQ05.INP contains one encoder‑homing‑frame. SEQ05.DEC contains one decoder‑homing‑frame. The use of these sequences is described in GSM 06.02 [8].
Table 5: Location and size of speech codec te... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7 DTX test sequences | This clause describes the test sequences designed to exercise the VAD algorithm (GSM 06.42 [6]), comfort noise (GSM 06.22 [4]) and discontinuous transmission (GSM 06.41 [5]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.1 Codec configuration | The VAD, comfort noise and discontinuous transmission shall be tested in conjunction with the speech encoder [2]). The speech encoder shall be configured to operate in the DTX mode defined in GSM 06.22 [4]. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2 DTX test sequences | Each DTX test sequence consists of four files:
‑ Files for input to the GSM half rate speech encoder: *.INP
‑ Files for comparison with the encoder output *.COD
‑ Files for input to the GSM half rate speech decoder: *.DEC
‑ Files for comparison with the decoder output: *.OUT
The *.DEC files are generated from the corre... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.1 Predictor values computation | The computation of the predictor values described in GSM 06.42 [6] is not tested explicitly, since the results from the computation are tested many times via the spectral comparison and threshold adaptation tests. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.2 Spectral comparison | The spectral comparison algorithm described in GSM 06.42 [6] is tested by the following test sequence:
‑ DTX01.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.3 Threshold adaptation | The threshold adaptation algorithm described in GSM 06.42 [6] is tested by the following test sequence:
‑ DTX02.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.4 Periodicity detection | The periodicity detection algorithm described in GSM 06.42 [6] is tested by the following test sequence:
‑ DTX03.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.5 Tone detection | The tone detection algorithm described in GSM 06.42 [6] is tested by the following test sequence:
‑ DTX04.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.6 Safety and initialization | This sequence checks the safety paths used to prevent zero values being passed to the norm function. It checks the functions described in the adaptive filtering and energy computation, and the prediction values computation given in GSM 06.42 [6]. This sequence also checks the initialization of thvad and the rvad array:... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.7 Comfort noise test sequence | The test sequences described in sub‑clauses 7.2.2 to 7.2.6 are designed to exercise the VAD described in GSM 06.42 [6] and the discontinuous transmission described in GSM 06.41 [5]. The following test sequence is defined to exercise the comfort noise algorithm described in GSM 06.22 [4]:
‑ DTX06.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.8 Real speech and tones | The test sequences cannot be guaranteed to find every possible error. There is therefore a small possibility that an incorrect implementation produces the correct output for the test sequences, but fails with real signals. Consequently, an extra sequence is included, which consists of very clean speech, barely detectab... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8 Sequences for finding the 20 ms framing of the GSM half rate speech encoder | When testing the decoder, alignment of the test sequences used to the decoder framing is achieved by the air interface (testing of MS) or can be reached easily on the Abis‑interface (testing on network side).
When testing the encoder, usually there is no information available about where the encoder starts its 20 ms se... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8.1 Bit synchronization | The input to the speech encoder is a series of 13 bit long words (104 kbits/s, 13 bit linear PCM). When starting to test the speech encoder, no knowledge is available on bit synchronization, i.e. where the encoder expects its least significant bits, and where it expects the most significant bits.
The encoder homing fra... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8.2 Frame synchronization | Once bit synchronization is found, frame synchronization can be found by inputting one special frame that delivers 160 different output frames, depending on the 160 different positions that this frame can possibly have with respect to the encoder framing.
This special synchronization frame was found by taking one input... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8.3 Formats and sizes of the synchronization sequences | BIT SYNC.INP:
This sequence consists of 13 frame triplets. It has the format of the speech encoder input test sequences (13 bit left justified with the three least significant bits set to zero).
The size of it is therefore:
SIZE (BITSYNC.INP) = 13 * 3 * 160 * 2 bytes = 12480 bytes.
SEQSYNC.INP:
This sequence consists o... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 9 Trau Testing with 8 Bit A- and µ-law PCM Test Sequences | In the previous clauses tests for the transcoder in the TRAU are described using 13 bit linear test sequences. However, these 13 bit test sequences require a special interface in the Trau and do not allow testing in the field. In most cases the TRAU has to be set in special mode before testing.
As an option, the speech... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 10 Test sequences for the GSM half rate speech codec | NOTE: This clause is contained in archive en_300968v080001p0.ZIP which accompanies the present document.
Annex A (informative):
Change Request History
Change history
SMG No.
TDoc. No.
CR. No.
Section affected
New version
Subject/Comments
SMG#16
4.0.3
ETSI Publication
SMG#20
5.0.1
Release 1996 version
SMG#23
97-737
A003... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 0.1 Scope | The present document specifies the Voice Activity Detector (VAD) to be used in the Discontinuous Transmission (DTX) as described in GSM 06.31. It also specifies the test methods to be used to verify that a VAD complies with the technical specification.
The requirements are mandatory on any VAD to be used either in the ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 0.2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or non‑specific.
• For a specific reference, subsequent revisions do not apply.
• Fo... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 0.3 Abbreviations | Abbreviations used in the present document are listed in GSM 01.04 [1]. |
ad3845652ec99fdffd75badceec5143f | 06.32 | 1 General | The function of the VAD is to indicate whether each 20 ms frame produced by the speech encoder contains speech or not. The output is a binary flag which is used by the TX DTX handler defined in GSM 06.31 [4].
The ETS is organized as follows.
Clause 2 describes the principles of operation of the VAD.
In clause 3, the co... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2 Functional description | The purpose of this clause is to give the reader an understanding of the principles of operation of the VAD, whereas the detailed description is given in clause 3. In case of discrepancy between the two descriptions, the detailed description of clause 3 shall prevail.
In the following clauses of clause 2, a Pascal prog... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.1 Overview and principles of operation | The function of the VAD is to distinguish between noise with speech present and noise without speech present. The biggest difficulty for detecting speech in a mobile environment is the very low speech/noise ratios which are often encountered. The accuracy of the VAD is improved by using filtering to increase the speech... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2 Algorithm description | The block diagram of the VAD algorithm is shown in figure 2.1. The individual blocks are described in the following clauses. ACF, N and sof are calculated in the speech encoder.
Figure 2.1: Functional block diagram of the VAD
The global variables shown in the block diagram are described as follows:
‑ ACF are auto‑corre... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.1 Adaptive filtering and energy computation | Pvad is computed as follows:
This corresponds to performing an 8th order block filtering on the input samples to the speech encoder, after zero offset compensation and pre‑emphasis. This is explained in clause A.1. |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.2 ACF averaging | Spectral characteristics of the input signal have to be obtained using blocks that are larger than one 20 ms frame. This is done by averaging the auto‑correlation values for several consecutive frames. This averaging is given by the following equations:
Where n represents the current frame, n‑1 represents the previous ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.3 Predictor values computation | The filter predictor values aav1 are obtained from the auto‑correlation values av1 according to the equation:
where:
‑ ‑
R = | av1[0], av1[1], av1[2], av1[3], av1[4], av1[5], av1[6], av1[7] |
| av1[1], av1[0], av1[1], av1[2], ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.4 Spectral comparison | The spectra represented by the autocorrelated predictor values rav1 and the averaged auto‑correlation values av0 are compared using the distortion measure dm defined below. This measure is used to produce a Boolean value stat every 20 ms, as given by these equations:
difference = |dm ‑ lastdm|
lastdm = dm
stat = differ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.5 Periodicity detection | The frequency spectrum of mobile noise is relatively stationary over quite long periods. The Inverse Filter Autocorrelated Predictor coefficients of the adaptive filter rvad are only updated when this stationarity is detected. Vowel sounds however, also have this stationarity, but can be excluded by detecting the perio... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.6 Information tone detection | The tone flag is only evaluated in the downlink VAD. In the uplink VAD, tone detection is not performed and tone = false.
Computation of the tone flag is complex. It is therefore evaluated after the processing of the current speech encoder frame. In this way transmission of the speech or SID frame is not delayed.
Infor... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.7 Threshold adaptation | A check is made every 20 ms to determine whether the VAD decision threshold (thvad) should be changed. This adaptation is carried out according to the flowchart shown in figure 2.2. The constants used are given in table 2.5.
Adaptation takes place in two different situations: firstly whenever ACF[0] is very low and sec... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.8 VAD decision | Prior to hangover the VAD decision condition is:
vvad = pvad > thvad |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.9 VAD hangover addition | VAD hangover is only added to bursts of speech greater than or equal to burstconst blocks. The Boolean variable vad indicates the decision of the VAD with hangover included. The values of the constants are given in table 2.6. The hangover algorithm is as follows:
if vvad then increment(burstcount) else burstcount = 0
i... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3 Computational details | In the next paragraphs, the detailed description of the VAD algorithm follows the preceding high level description. This detailed description is divided in ten clauses related to the blocks of figure 2.1 (except periodicity updating) in the high level description of the VAD algorithm.
Those clauses are:
1) adaptive fil... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.1 Adaptive filtering and energy computation | This clause computes the e_pvad and m_pvad variables which represent the pvad value. It needs the L_ACF[0..8] and scalauto variables of the RPE‑LTP algorithm and the rvad[0..8] and normrvad variables produced by clause 3.6 of the VAD algorithm. It also computes a floating point representation of L_ACF[0] (e_acf0 and m_... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.2 ACF averaging | This clause uses the L_ACF[0..8] and the scalvad variables to compute the array L_av0[0..8] and L_av1[0..8] used in clause 3.3 and 3.4.
Computation of the scaling factor:
scal = sub( 10, (scalvad << 1) );
Computation of the arrays L_av0[0..8] and L_av1[0..8]:
| FOR i = 0 to 8:
| L_temp = L_ACF[i] >> scal;
| L_av0[i] ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.3 Predictor values computation | This clause computes the array rav1[0..8] needed for the spectral comparison and the threshold adaptation. It uses the L_av1[0..8] computed in clause 3.2, and is divided in the three following clauses:
‑ Schur recursion to compute reflection coefficients.
‑ Step up procedure to obtain the aav1[0..8].
‑ Computation of t... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.3.1 Schur recursion to compute reflection coefficients | This clause is identical to the one used in the RPE‑LTP algorithm. The array vpar[1..8] is computed with the array L_av1[0..8] as an input.
Schur recursion with 16 bits arithmetic:
IF( L_av1[0] == 0 ) THEN
|== FOR i = 1 to 8:
| vpar[i] = 0;
|== NEXT i:
| EXIT; /continue with clause 3.3.2/
temp = norm( L_av1[0] );... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.3.2 Step‑up procedure to obtain the aav1[0..8] | Initialization of the step‑up recursion:
L_coef[0] = 16384 << 15;
L_coef[1] = vpar[1] << 14;
Loop on the LPC analysis order:
|= FOR m = 2 to 8:
|== FOR i = 1 to m‑1:
|== temp = L_coef[m‑i] >> 16; / takes the msb /
|== L_work[i] = L_add( L_coef[i], L_mult( vpar[m], temp ) );
|== NEXT i
|=
|== FOR i = 1 to m‑1:
|== L... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.3.3 Computation of the rav1[0..8] | |= FOR i= 0 to 8:
|= L_work[i] = 0;
|== FOR k = 0 to 8‑i:
|== L_work[i] = L_add( L_work[i], L_mult( aav1[k], aav1[k+i] ) );
|== NEXT k:
|= NEXT i:
IF ( L_work[0] == 0 ) THEN normrav1 =0;
ELSE normrav1 = norm( L_work[0] );
|= FOR i= 0 to 8:
|= rav1[i] = ( L_work[i] << normrav1 ) >> 16;
|= NEXT i:
Keep the normrav1 for ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.4 Spectral comparison | This clause computes the variable stat needed for the threshold adaptation. It uses the array L_av0[0..8] computed in clause 3.2 and the array rav1[0..8] computed in clause 3.3.3.
Re‑normalize L_av0[0..8]:
IF ( L_av0[0] == 0 ) THEN
| FOR i = 0 to 8:
| sav0[i] = 4095;
| NEXT i:
ELSE
| shift = norm( L_av0[0] );
|= FOR i... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.5 Periodicity detection | This clause just sets the ptch flag needed for the threshold adaptation.
temp = add( oldlagcount, veryoldlagcount );
IF ( temp >= 4 ) THEN ptch = 1;
ELSE ptch = 0; |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.6 Threshold adaptation | This clause uses the variables e_pvad, m_pvad, e_acf0 and m_acf0 computed in clause 3.1. It also uses the flags stat (see clause 3.4) and ptch (see clause 3.5). It follows the flowchart represented on figure 2.2.
Some constants, represented by a floating point format, are needed and a symbolic name (in capital letter) ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.7 VAD decision | This clause only outputs the result of the comparison between pvad and thvad using the pseudo‑floating point representation of thvad and pvad. The values e_pvad and m_pvad are computed in clause 3.1 and the values e_thvad and m_thvad are computed in clause 3.6.
vvad = 0;
IF (e_pvad > e_thvad) THEN vvad = 1;
IF (e_pvad... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.8 VAD hangover addition | This clause finally sets the vad decision for the current frame to be processed.
IF ( vvad == 1 ) THEN burstcount = add( burstcount, 1 );
ELSE burstcount = 0;
IF ( burstcount >= 3 ) THEN
| hangcount = 5;
| burstcount = 3;
vad = vvad;
IF ( hangcount >= 0 ) THEN
| vad = 1;
| hangcount = sub( hangcount, 1 ); |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.9 Periodicity updating | This clause must be delayed until the LTP lags are computed by the RPE‑LTP algorithm. The LTP lags called Nc in the speech encoder are renamed lags[0..3] (index 0 for the first sub‑ segment of the frame, 1 for the second and so on).
Loop on sub‑segments for the frame:
lagcount = 0;
|= FOR i = 0 to 3:
|= Search the max... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10 Tone detection | This clause computes the tone variable needed for the threshold adaptation. Tone is only calculated for the VAD in the downlink. In the uplink VAD tone=0.
To reduce delay, this clause should be calculated after the processing of the current speech encoder frame. |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10.1 Windowing | This clause applies a Hanning window to the input frame sof[0..159] to form the output frame sofh[0..159]. The input frame is the current offset compensated signal frame calculated in the RPE‑LTP codec. The array of constants hann[i] is defined in table 3.2.
Multiply signal frame by Hanning window:
|== FOR i = 0 to 79:... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10.2 Auto‑correlation | This clause computes the auto‑correlation vector L_acfh[0..5] from the windowed input frame sofh[0..159]. The input frame must be scaled in order to avoid an overflow situation. This clause is identical to the one used in the RPE‑LTP algorithm, with the exception that only five auto‑correlation values are calculated.
D... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10.3 Computation of the reflection coefficients | This clause calculates the reflection coefficients rc[1..4] from the input array L_acfh[0..4]. This procedure is identical to the one in clause 3.3.1 and the RPE‑LTP codec, with the exception that only four reflection coefficients are calculated.
Schur recursion with 16 bits arithmetic:
IF( L_acfh[0] == 0 ) THEN
|== FO... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10.4 Filter coefficient calculation | This clause calculates the direct form filter coefficients a[1..2] from the reflection coefficients rc[1..4].
Step‑up procedure to obtain the a[1..2]:
temp = rc[1] >> 2;
a[1] = add( temp, mult_r( rc[2], temp ) );
a[2] = rc[2] >> 2; |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10.5 Pole Frequency Test | This clause uses the direct form filter coefficients a[1..2] to determine the pole frequency of the second order LPC analysis. If the pole frequency is less than 385 Hz tone is set to 0 and clause 3 terminates.
L_den = L_mult ( a[1], a[1] );
L_temp = a[2] << 16;
L_num = L_sub ( L_temp, L_den );
If pole is not complex t... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.10.6 Prediction gain test | This clause uses the reflection coefficients rc[1..4] to calculate the prediction gain. If the prediction gain is greater than 13,5 dB then tone is set to 1 otherwise tone is set to 0.
Calculate normalized prediction error:
prederr = 32767;
|== FOR i=1 to 4
| temp = mult ( rc[i], rc[i] );
| temp = sub ( 32767, te... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 4 Digital test sequences | This clause provides information on the digital test sequences that have been designed to help the verification of implementations of the Voice Activity Detector. Copies of these sequences are available (see clause A.2). |
ad3845652ec99fdffd75badceec5143f | 06.32 | 4.1 Test configuration | The VAD must be tested in conjunction with the speech encoder defined in GSM 06.10. The test configuration is shown in figure 4.1. The input signal to the speech encoder is the sop[...] signal as defined in GSM 06.10 table 5.1. The relevant parameters produced by the speech encoder are input to the VAD algorithm to pro... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 4.2 Test sequences | The test sequences are described in detail in clause A.2.
Annex A (informative):
A.1 Simplified block filtering operation
Consider an 8th order transversal filter with filter coefficients a0..a8, through which a signal is being passed, the output of the filter being:
(1)
If we apply block filtering over 20 ms segments,... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 1 Scope | The present document specifies the digital test sequences for the GSM enhanced full rate speech codec. These sequences test for a bit exact implementation of the enhanced full rate speech transcoder (GSM 06.60 [2]), Voice Activity Detection (GSM 06.82 [6]), comfort noise (GSM 06.62 [4]) and the discontinuous transmissi... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or non‑specific.
• For a specific reference, subsequent revisions do not apply.
• Fo... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 3 Definitions and abbreviations | |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 3.1 Definitions | Definition of terms used in the present document can be found in GSM 06.60 [2], GSM 06.61 [3], GSM 06.62 [4], GSM 06.81 [5] and GSM 06.82 [6]. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply:
ETS European Telecommunication Standard
GSM Global System for Mobile communications
For abbreviations not given in this subclause see GSM 01.04 [1]. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 4 General | Digital test sequences are necessary to test for a bit exact implementation of the enhanced full rate speech transcoder (GSM 06.60 [2]), Digital test Voice Activity Detection (GSM 06.82 [6]), comfort noise (GSM 06.62 [4]) and the discontinuous transmission (GSM 06.81 [5]).
The test sequences may also be used to verify ... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 5 Test sequence format | This clause provides information on the format of the digital test sequences for the GSM enhanced full rate speech transcoder (GSM 06.60 [2]), Voice Activity Detection (GSM 06.82 [6]), comfort noise (GSM 06.62 [4]) and the discontinuous transmission (GSM 06.81 [5]). |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 5.1 File format | The test sequence files are provided in archive ts_100725v080100p0.zip which accompanies the present document.
Following decompression, four types of file are provided:
- Files for input to the GSM enhanced full rate speech encoder: *.INP
- Files for comparison with the encoder output: *.COD
- Files for input to t... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 5.2 Codec homing | Each *.INP file includes two homing frames at the start of the test sequence. The function of these frames is to reset the speech encoder state variables to their initial value. In the case of a correct installation of the ANSI-C simulation (GSM 06.53 [7]), all speech encoder output frames shall be identical to the cor... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 6 Speech codec test sequences | This clause describes the test sequences designed to exercise the GSM enhanced full rate speech transcoder (GSM 06.60 [2]). |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 6.1 Codec configuration | The speech encoder shall be configured to operate in the non-DTX mode. The VAD and SP flags shall be set to 1 at the speech encoder output. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 6.2 Speech codec test sequences | Table 5 lists the location and size of the speech codec test sequences. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 6.2.1 Speech encoder test sequences | Twenty-one encoder input sequences are provided. Note that for the input sequences TEST0.INP to TEST3.INP, the amplitude figures are given in 13-bit precision. The active speech levels are given in dBov.
- TEST0.INP - Synthetic harmonic signal. The pitch delay varies slowly from 18 to 143.5 samples. The minimum and max... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 6.2.2 Speech decoder test sequences | Twenty-one speech decoder input sequences TESTXX.DEC (XX = 0..20) are provided. These are derived from the corresponding TESTXX.INP sequences. In a correct implementation, the resulting speech decoder output shall be identical to the corresponding TESTXX.OUT sequences. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 6.2.3 Codec homing sequence | In addition to the test sequences described above, two homing sequences are provided to assist in codec testing. TEST21.INP contains one encoder-homing-frame. TEST21.DEC contains one decoder-homing-frame. The use of these sequences is described in GSM 06.51 [8].
Table 5: Location and size of speech codec test sequences... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7 DTX test sequences | This subclause describes the test sequences designed to exercise the VAD algorithm (GSM 06.82 [6]), comfort noise (GSM 06.62 [4]) and discontinuous transmission (GSM 06.81 [5]). |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.1 Codec configuration | The VAD, comfort noise and discontinuous transmission shall be tested in conjunction with the speech encoder (GSM 06.60 [2]). The speech encoder shall be configured to operate in the DTX mode defined in GSM 06.62 [4]. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2 DTX test sequences | Each DTX test sequence consists of four files:
- Files for input to the GSM enhanced full rate speech encoder: *.INP
- Files for comparison with the encoder output: *.COD
- Files for input to the GSM enhanced full rate speech decoder: *.DEC
- Files for comparison with the decoder output: *.OUT
The *.DEC files... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.1 Predictor values computation | The computation of the predictor values described in GSM 06.82 [6] is not tested explicitly, since the results from the computation are tested many times via the spectral comparison and threshold adaptation tests. |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.2 Spectral comparison | The spectral comparison algorithm described in GSM 06.82 [6] is tested by the following test sequence:
- DTX01. * |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.3 Threshold adaptation | The threshold adaptation algorithm described in GSM 06.82 [6] is tested by the following test sequence:
- DTX02. * |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.4 Periodicity detection | The periodicity detection algorithm described in GSM 06.82 [6] is tested by the following test sequence:
- DTX03. * |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.5 Tone detection | The tone detection algorithm described in GSM 06.82 [6] is tested by the following test sequence:
- DTX04. * |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.6 Safety and initialisation | This sequence checks the safety paths used to prevent zero values being passed to the norm function. It checks the functions described in the adaptive filtering and energy computation, and the prediction values computation given in GSM 06.82 [6]. This sequence also checks the initialisation of thvad and the rvad array... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.7 Comfort noise test sequence | The test sequences described in sub-subclauses 7.2.2 to 7.2.6 are designed to exercise the VAD described in GSM 06.82 [6] and the discontinuous transmission described in GSM 06.81 [5]. The following test sequence is defined to exercise the comfort noise algorithm described in GSM 06.62 [4]:
- DTX06.* |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 7.2.8 Real speech and tones | The test sequences cannot be guaranteed to find every possible error. There is therefore a small possibility that an incorrect implementation produces the correct output for the test sequences, but fails with real signals. Consequently, an extra sequence is included, which consists of very clean speech, barely detecta... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 8 Sequences for finding the 20 ms framing of the GSM enhanced full rate speech encoder | When testing the decoder, alignment of the test sequences used to the decoder framing is achieved by the air interface (testing of MS) or can be reached easily on the Abis-interface (testing on network side).
When testing the encoder, usually there is no information available about where the encoder starts its 20 ms se... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 8.1 Bit synchronisation | The input to the speech encoder is a series of 13 bit long words (104 kbits/s, 13 bit linear PCM). When starting to test the speech encoder, no knowledge is available on bit synchronisation, i.e., where the encoder expects its least significant bits, and where it expects the most significant bits.
The encoder homing fr... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 8.2 Frame synchronisation | Once bit synchronisation is found, frame synchronisation can be found by inputting one special frame that delivers 160 different output frames, depending on the 160 different positions that this frame can possibly have with respect to the encoder framing.
This special synchronisation frame was found by taking one input... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 8.3 Formats and sizes of the synchronisation sequences | BIT SYNC.INP:
This sequence consists of 13 frame triplets. It has the format of the speech encoder input test sequences (13 bit left justified with the three least significant bits set to zero).
The size of it is therefore:
SIZE (BITSYNC.INP) = 13 * 3 * 160 * 2 bytes = 12480 bytes
SEQSYNC.INP:
This sequence consist of ... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 9 Trau Testing with 8 Bit A- and µ-law PCM Test Sequences | In the previous clauses, tests for the transcoder in the TRAU are described, using 13 bit linear test sequences. However, these 13 bit test sequences require a special interface in the TRAU and do not allow testing in the field. In most cases the TRAU has to be set in special mode before testing.
As an alternative, th... |
2d561ed8a3b06dda8ca0195c2d72b489 | 06.54 | 10 Alternative Enhanced Full Rate implementation using the Adaptive Multi Rate 12.2 kbit/s mode | The 12.2 kbit/s mode of the Adaptive Multi Rate speech coder described in TS 26.071 is functionally equivalent to the GSM Enhanced Full Rate speech coder. An alternative implementation of the Enhanced Full Rate speech service based on the 12.2 kbit/s mode of the Adaptive Multi Rate coder is allowed. Alternative impleme... |
d584819bc08aaf1044fa432bfa99ac6d | 08.20 | 1 Scope | The present document defines rate adaptation functions to be used in GSM PLMN Base Station Systems (BSS) transcoders and IWF for adapting radio interface data rates to the 64 kbit/s used at the A-interface in accordance with 3GPP TS 03.10.
The number of Base Station System - Mobile-services Switching Centre (BSS - MSC)... |
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