Normalization and polygon error detection for split VQ of line spectral frequencies

A technique for improving the performance of split vector quantization (VQ) of line spectral frequency (LSF) parameters is presented, wherein a normalization process is used to make all combinations of the codebook entries valid for preserving the LSF ordering property. An undesirable consequence of normalization is a reduction in the ability to detect bit errors in the LSF codebook indices by exploiting the ordering property. A new method, polygon error detection (PED), is presented which shows promise for overcoming this problem. The use of PED is also shown to be beneficial when normalization is not performed.