Robust vector quantization of line spectral frequencies
US5651026A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 27, 1995 |
| Grant date | Jul 22, 1997 |
| Priority date | — |
| Expiry date | Jun 27, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L25/24
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A line spectral frequency (LSF) vector quantizer, having particular application in digital cellular networks (DCN), is provided for code excited linear predictive (CELP) speech encoders. The LSF vector quantizer is efficient in terms of bits employed, robust and effective in terms of performance across speakers and handsets, moderate in terms of complexity, and accommodates effective and simple built-in transmission error detection schemes. The LSF vector quantizer employs a minimum number of bits, is of moderate complexity and incorporates built-in error detection capability in order to combat transmission errors. The LSF vector quantizer classifies unquantized line spectral frequencies into four categories, employing different vector quantization tables for each category. Each quantization table is optimized for particular types of vectors. For each category, three split vector codebooks are used with a simplified error measure to find three candidate split quantized vectors. The three sets of three split vectors are combined to produce as many as 27 vectors from each category. The quantizer then makes a final selection of optimal category using a more complex error measure to ac…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.