1、 ETSI TS 1Digital cellular telecoUniversal Mobile TelMandatory speech coAdaptive MultVoice A(3GPP TS 26.0TECHNICAL SPECIFICATION126 094 V13.0.0 (2016communications system (Phaelecommunications System (LTE; codec speech processing funulti-Rate (AMR) speech codecActivity Detector (VAD) .094 version 13
2、.0.0 Release 1316-01) hase 2+); (UMTS); functions; ec; 13) ETSI ETSI TS 126 094 V13.0.0 (2016-01)13GPP TS 26.094 version 13.0.0 Release 13Reference RTS/TSGS-0426094vd00 Keywords GSM,LTE,UMTS ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65
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12、TSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, U
13、MTS identities or GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall
14、“, “shall not“, “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used i
15、n direct citation. ETSI ETSI TS 126 094 V13.0.0 (2016-01)33GPP TS 26.094 version 13.0.0 Release 13Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Technical Description of VAD Option 1 5g33.1 Definitions, symbols and abbrevi
16、ations 5g33.1.1 Definitions 5g33.1.2 Symbols 5g33.1.2.1 Variables . 5g33.1.2.2 Constants. 6g33.1.2.3 Functions . 7g33.1.3 Abbreviations 7g33.2 General . 7g33.3 Functional description 7g33.3.1 Filter bank and computation of sub-band levels . 8g33.3.2 Pitch detection 10g33.3.3 Tone detection 10g33.3.4
17、 Correlated Complex Signal Analysis (and detection) . 11g33.3.5 VAD decision . 11g33.3.5.1 Hangover addition . 12g33.3.5.2 Background noise estimation 14g34 Technical Description of VAD Option 2 16g34.1 Definitions, symbols and abbreviations 16g34.1.1 Definitions 16g34.1.2 Symbols 16g34.1.2.1 Variab
18、les . 16g34.1.2.2 Constants. 17g34.1.2.3 Functions . 17g34.1.3 Abbreviations 18g34.2 General . 18g34.3 Functional description 18g34.3.1 Frequency Domain Conversion 19g34.3.2 Channel Energy Estimator 19g34.3.3 Channel SNR Estimator 20g34.3.4 Voice Metric Calculation 20g34.3.5 Frame SNR and Long-Term
19、Peak SNR Calculation . 20g34.3.6 Negative SNR Sensitivity Bias . 21g34.3.7 VAD Decision 21g34.3.8 Spectral Deviation Estimator 22g34.3.9 Sinewave Detection 22g34.3.10 Background Noise Update Decision . 23g34.3.10 Background Noise Estimate Update . 23g35 Computational details . 24g3Annex A (informati
20、ve): Change history . 25g3History 26g3ETSI ETSI TS 126 094 V13.0.0 (2016-01)43GPP TS 26.094 version 13.0.0 Release 13Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present document are subject to continuing work within the
21、 TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number as follows: Version x.y.z where: x the first digit: 1 presented to TSG for inf
22、ormation; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been
23、 incorporated in the document. ETSI ETSI TS 126 094 V13.0.0 (2016-01)53GPP TS 26.094 version 13.0.0 Release 131 Scope The present document specifies two alternatives for the Voice Activity Detector (VAD) to be used in the Discontinuous Transmission (DTX) as described in 3. Implementors of mobile sta
24、tion and infrastructure equipment conforming to the AMR specifications can choose which of the two VAD options to implement. There are no interoperability factors associated with this choice. The requirements are mandatory on any VAD to be used either in User Equipment (UE) or Base Station Systems (
25、BSS)s that utilize the AMR speech codec. 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-speci
26、fic. For a specific reference, subsequent revisions do not apply. For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release
27、as the present document. 1 3GPP TS 26.073: “Adaptive Multi-Rate (AMR); ANSI C source code“. 2 3GPP TS 26.090: “Transcoding functions“. 3 3 GPP TS 26.093: “Source Controlled Rate operation“. 4 ITU, The International Telecommunications Union, Blue Book, Vol. III, Telephone Transmission Quality, IXth P
28、lenary Assembly, Melbourne, 14-25 November, 1988, Recommendation G.711, Pulse code modulation (PCM) of voice frequencies. 3 Technical Description of VAD Option 1 3.1 Definitions, symbols and abbreviations 3.1.1 Definitions For the purposes of the present document, the following terms and definitions
29、 apply: frame: time interval of 20 ms corresponding to the time segmentation of the speech transcoder 3.1.2 Symbols For the purposes of the present document, the following symbols apply. 3.1.2.1 Variables bckr_estn background noise estimate burst_count counts length of a speech burst, used by VAD ha
30、ngover addition hang_count hangover counter, used by VAD hangover addition complex_hang_count hangover counter, used by CAD hangover addition ETSI ETSI TS 126 094 V13.0.0 (2016-01)63GPP TS 26.094 version 13.0.0 Release 13complex_hang_timer hangover initator, used fo Complex Activity Estimation lagco
31、unt pitch detection counter leveln signal level new_speech pointer of the speech encoder, points a buffer containing last received samples of a speech frame 2 noise_level average level of the background noise estimate oldlagcount lagcount of the previous frame pitch flag indicating presence of a per
32、iodic signal complex_warning flag indicating the presence of a complex signal. best_corr_hp normalized and limited value from maximum HP filtered correlation vector corr_hp filtered best_corr_hp values pow_sum power of the input frame s(i) samples of the input framer snr_sum measure between input fr
33、ame and noise estimate stat_count stationarity counter stat_rat measure indicating stationary T_opn open-loop lags 2 t0 autocorrelation maxima calculated by the open-loop pitch analysis 2 t1 signal power related to the autocorrelation maxima t0 2 tone flag indicating the presence of a tone vad_thr V
34、AD threshold VAD_flag boolean VAD flag vadreg intermediate VAD decision complex_low intermediate complex signal decisions complex_high intermediate complex signal decisions 3.1.2.2 Constants ALPHA_UP1 constant for updating noise estimate (see clause 3.3.5.2) ALPHA_DOWN1 constant for updating noise e
35、stimate (see clause 3.3.5.2) ALPHA_UP2 constant for updating noise estimate (see clause 3.3.5.2) ALPHA_DOWN2 constant for updating noise estimate (see clause 3.3.5.2) ALPHA3 constant for updating noise estimate (see clause 3.3.5.2) ALPHA4 constant for updating average signal level (see clause 3.3.5.
36、2) ALPHA5 constant for updating average signal level (see clause 3.3.5.2) BURST_LEN_HIGH_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.1) BURST_LEN_LOW_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.1) COEFF3 coefficient for the filter bank (see claus
37、e 3.3.1) COEFF5_1 coefficient for the filter bank (see clause 3.3.1) COEFF5_2 coefficient for the filter bank (see clause 3.3.1) HANG_LEN_HIGH_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.1) HANG_LEN_LOW_NOISE constant for controlling VAD hangover addition (see clause 3.3.5
38、.2) HANG_NOISE_THR constant for controlling VAD hangover addition (see clause 3.3.5.2) L_FRAME size of a speech frame, 160 L_NEXT length for the lookahead of the speech encoder, 40 LTHRESH threshold for pitch detection (see clause 3.3.2) NOISE_MAX maximum value for noise estimate (see clause 3.3.5.2
39、) NOISE_MIN minimum value for noise estimate (see clause 3.3.5.2) NTHRESH threshold for pitch detection (see clause 3.3.2) POW_PITCH_THR threshold for pitch detection (see clause 3.3.5) POW_COMPLEX_THR threshold for complex detection (see clause 3.3.5) STAT_COUNT threshold for stationary detection (
40、see clause 3.3.5.2) CAD_MIN_STAT_COUNT minimum threshold after complex warning STAT_THR threshold for stationary detection (see clause 3.3.5.2) STAT_THR_LEVEL threshold for stationary detection (see clause 3.3.5.2) TONE_THR threshold for tone detection (see clause 3.3.3) VAD_P1 constant of computati
41、on for VAD threshold (see clause 3.3.5.2) VAD_POW_LOW constant for controlling VAD hangover addition (see clause 3.3.5.1) VAD_SLOPE constant of computation for VAD threshold (see clause 3.3.5) VAD_THR_HIGH constant of computation for VAD threshold (see clause 3.3.5) ETSI ETSI TS 126 094 V13.0.0 (201
42、6-01)73GPP TS 26.094 version 13.0.0 Release 13CVAD_THRESH_ADAPT_HIGH constant for updating complex_high CVAD_THRESH_ADAPT_LOW constant for updating complex_low CVAD_THRESH_HANG constant for updating complex_hang_timer CVAD_HANG_LIMIT constant for initiating complex_hang_count CVAD_HANG_LENGTH consta
43、nt for resetting complex_hang_count 3.1.2.3 Functions + addition- subtraction * multiplication / division | x | absolute value of x AND Boolean ANDOR Boolean ORxnnab()=MIN(x,y) = MAX(x,y) = 3.1.3 Abbreviations For the purposes of the present document, the following abbreviations apply: ANSI American
44、 National Standards Institute DTX Discontinuous Transmission VAD Voice Activity Detector CAD Complex Activity Detection CNG Comfort Noise Generation 3.2 General The function of the VAD algorithm is to indicate whether each 20 ms frame contains signals that should be transmitted, i.e. speech, music o
45、r information tones. The output of the VAD algorithm is a Boolean flag (VAD_flag) indicating presence of such signals. 3.3 Functional description The block diagram of the VAD algorithm is depicted in figure 1. The VAD algorithm uses parameters of the speech encoder to compute the Boolean VAD flag (V
46、AD_flag). Samples of the Input frame (s(i) are divided into sub-bands and level of the signal in each band (leveln) is calculated. Input for the pitch detection function are open-loop lags (T_opn), which are calculated by open-loop pitch analysis of the speech encoder. The pitch detection function c
47、omputes a flag (pitch) which indicates presence of pitch. Tone detection function calculates a flag (tone), which indicates presence of an information tone. Tones are detected based on pitch gain of the open-loop pitch analysis The pitch gain is estimated using autocorrelation values (t0 and t1) rec
48、eived from the pitch analysis. Complex Signal Detection function calculates a flag (complex_warning), which indicates presence of a correlated complex signal such as music. Correlate complex signals are detected based on analysis of the correlation vector available in the open-loop pitch analysis.Th
49、e VAD decision function estimates background noise levels. Intermediate VAD decision is calculated based on the comparison of the background noise estimate and levels of the input frame (leveln). Finally, the VAD flag is calculated by adding hangover to the intermediate VAD decision. () ( ) ( ) ()=+xa xa xb xb11Kxyyyxx,ETSI ETSI TS 126 094 V13.0.0 (2016-01)83GPP TS 26.094 version 13.0.0 Release 13Figure 3.1: Simplified block diagram of the VAD algori
