초록 ▼

The performance of digital communication over a noisy communication channel is improved. An encoder combines bit modulation with error control encoding to allow the decoder to use the redundancy in the error control codes to detect uncorrectable bit errors. This method improves the efficiency of the

The performance of digital communication over a noisy communication channel is improved. An encoder combines bit modulation with error control encoding to allow the decoder to use the redundancy in the error control codes to detect uncorrectable bit errors. This method improves the efficiency of the communication system since fewer bits are required for error control, leaving more bits available for data. In the context of a speech coding system, speech quality is improved without sacrificing robustness to bit errors. A bit prioritization method further improves performance over noisy channels. Individual bits in a set of quantizer values are arranged according to their sensitivity to bit errors. Error control codes having higher levels of redundancy are used to protect the most sensitive (highest priority) bits, while lower levels of redundancy are used to protest less sensitive bits. This method improves efficiency of the error control system, since only the highest priority data is encoded with the highest levels of redundancy. The effect of uncorrectable bit errors is reduced by adaptively smoothing the spectral parameters in a speech decoder. The amount of smoothing is varied depending upon the number of errors detected during the error control decoding of the received data. More smoothing is used when a large number of errors are detected, thereby reducing the perceived effect of any uncorrectable bit errors which may be present.

대표청구항 ▼

[ We claim:] [1.] A method for encoding digital data in which a set of quantizer values is encoded into a plurality of bit vectors, each quantizer value containing a non-negative number of bit locations, the method comprising the steps of:assigning each bit location in said quantizer values a weight

[ We claim:] [1.] A method for encoding digital data in which a set of quantizer values is encoded into a plurality of bit vectors, each quantizer value containing a non-negative number of bit locations, the method comprising the steps of:assigning each bit location in said quantizer values a weight, the weight weighing more-significant bit locations more heavily than less-significant bit locations of the same quantizer value;prioritizing all of said quantizer bit locations in the order of their weight, high priority given to bit locations with high weights; andpartitioning bits associated with said prioritized bit locations into contiguous blocks to form bit vectors,wherein some of said quantizer values represent the spectrum of an acoustic signal, and bits in a first quantizer value are given higher weight than bits of the same significance in a second quantizer value.