Content for TS 46.020 Word version: 18.0.0
3 Definitions, symbols and abbreviations
4 Functional description of the GSM half rate speech codec
5 Homing sequences
A Codec parameter description
B Order of occurrence of the codec parameters over Abis
C Bibliography
$ Change History
3 Definitions, symbols and abbreviations p. 6
4 Functional description of the GSM half rate speech codec p. 10
4.1 GSM half rate speech encoder p. 10
4.1.1 High-pass filter p. 12
4.1.2 Segmentation p. 13
4.1.3 Fixed Point Lattice Technique (FLAT) p. 13
4.1.4 Spectral quantization p. 14
4.1.5 Frame energy calculation and quantization p. 16
4.1.6 Soft interpolation of the spectral parameters p. 16
4.1.7 Spectral noise weighting filter coefficients p. 17
4.1.8 Long Term Predictor lag determination p. 18
4.1.8.1 Open loop long term search initialization p. 19
4.1.8.2 Open loop lag search p. 20
4.1.8.3 Frame lag trajectory search (Mode ≠ 0) p. 25
4.1.8.4 Voicing mode selection p. 27
4.1.8.5 Closed loop lag search p. 27
4.1.9 Harmonic noise weighting p. 28
4.1.10 Code search algorithm p. 30
4.1.11 Multimode gain vector quantization p. 33
4.2 GSM half rate speech decoder p. 36
5 Homing sequences p. 39
5.1 Functional description p. 39
5.2 Definitions p. 39
5.3 Encoder homing p. 40
5.4 Decoder homing p. 40
5.5 Encoder home state p. 40
5.6 Decoder home state p. 40
A (Normative) Codec parameter description p. 41
A.1 Codec parameter description p. 41
A.1.1 MODE p. 41
A.1.2 R0 p. 41
A.1.3 LPC1 - LPC3 p. 42
A.1.4 LAG_1 - LAG_4 p. 42
A.1.5 CODEx_1 - CODEx_4 p. 42
A.1.6 GSP0_1 - GSP0_4 p. 42
A.2 Basic coder parameters p. 42
B (Normative) Order of occurrence of the codec parameters over Abis p. 43
C Bibliography p. 44
$ Change History p. 45
