STUDY ON SPEECH CODING IN SUB-BANDS AT 16 KBITS/S / ESTUDO DE CODIFICAÇÃO DE VOZ EM SUB-BANDAS A 16 KBIT/S
AUTOR(ES)
CARLOS FELIPE DE BRITO JACCOUD
DATA DE PUBLICAÇÃO
1986
RESUMO
In this thesis a study of 16 kbit/s sub-band coding of speech signals is presented. The encoding systems are examined in terms of the number of sub-bands, the schemes used to encode the sub-band signals, the parameters and techniques employed in the quantizers adaptation and the type of bit allocation. Spectral decomposition of the input signal is carried out by means of quadrature mirror filter (QMF) banks. The systems are evaluated through computer simulation, both in ideal and noisy channels, using the frequency - weighted signal-to-noise ratio as the performance criterion. The global and segmental signal- to-noise ratio performances are also given in all cases. After a detailed examination of the various systems, a coding structure is proposed , in which the configuration of the quantizer and its adaptation techniques depend on the sub-band to be coded. Furthermore, the proposed system uses an algorithm for bit allocation based on comparison of the energies fo blocks of samples in the several sub-bands.
ASSUNTO(S)
digital transmission transmissao digital codificacao de voz speech coding
