Digital speech coder having improved vector excitation source
US4817157A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 7, 1988 |
| Grant date | Mar 28, 1989 |
| Priority date | — |
| Expiry date | Jan 7, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L2019/0013
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An improved excitation vector generation and search technique (FIG. 1) is described for a code-excited linear prediction (CELP) speech coder (100) using a codebook of excitation code vectors. A set of M basis vectors V.sub.m (n) are used along with the excitation signal codewords (i) to generate the codebook of excitation vectors u.sub.i (n) according to a "vector sum" technique (120) of converting the selector codewords into a plurality of interim data signals, multiplying the set of M basis vectors by the interim data signals, and summing the resultant vectors to produce the set of 2.sup.M codebook vectors. The entire codebook of 2.sup.M possible excitation vectors is efficiently searched by using the vector sum generation technique with the M basis vectors--without ever having to generate and evaluate each of the 2.sup.M code vectors themselves. Furthermore, only M basis vectors need to be stored in memory (114), as opposed to all 2.sup.M code vectors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.