(19)
(11) EP 0 333 425 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
07.02.1990 Bulletin 1990/06

(43) Date of publication A2:
20.09.1989 Bulletin 1989/38

(21) Application number: 89302481.0

(22) Date of filing: 14.03.1989
(51) International Patent Classification (IPC)4: G10L 9/14
(84) Designated Contracting States:
AT BE CH DE ES FR GB GR IT LI LU NL SE

(30) Priority: 16.03.1988 GB 8806185

(71) Applicant: UNIVERSITY OF SURREY
Guildford, Surrey GU2 5XH (GB)

(72) Inventors:
  • Evans, Barry G. Dept. of Electronic & Elect. Eng.
    Guildford Surrey GU2 5XH (GB)
  • Kondoz, Ahmet M. Dept. of Electronic & Elect. Eng.
    Guildford Surrey GU2 5XH (GB)

(74) Representative: Knott, Stephen Gilbert et al
MATHISEN, MACARA & CO. The Coach House 6-8 Swakeleys Road
Ickenham Uxbridge UB10 8BZ
Ickenham Uxbridge UB10 8BZ (GB)


(56) References cited: : 
   
       


    (54) Speech coding


    (57) Speech for transmission over a low bit rate channel of a telecommunications link is digitally sampled and subjected to linear predictive coding in a coder (6). The LPC residual signal is passed through a weighting filter (18) and the output down sampled by decimation factor d resulting in d sequences of which the maximum energy sequence is selected for vector quantization. The data output from the vector quantizer (22) is formed into an output frame together with an index (s) identifying the selected decimation sequence and the quantized LPC parameters. The frame transmitted over the telecommunications link (46) is decoded by means of an inverse vector quantizer (50) which restores the decimated sequence. An interpolator (52) interpolates zeros to restore an excitation signal for an LPC synthesis filter (54) from which the voice signal can be reconstructed.







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