| 摘要 |
A system for low rate coding or decoding includes the use of a mode indicator in the coded signal to indicate whether prequantizer (i.e., coarse) or quantizer (i.e., fine) information is being sent. In a transmitter (300) embodiment both a prequantizer (212) and a restricted quantizer (214) search is performed of predefined prequantizer ("P") and quantizer ("V") codewords, respectively, to determine the codewords with the least residual energy. The index of the P or V codeword with the least residual is then determined (220), and this index is transmitted along with an appropriate P or V mode indicator. In a receiver (330) embodiment, the mode indicator is used to set the decoder (e.g., a vocoder) (350) to form a signal replica from a P codeword (determined from the transmitted index), or from a V codeword (from the transmitted V index) and previously determined P codeword (e.g., the centroid of the V codeword). |
