排序方式: 共有8条查询结果,搜索用时 31 毫秒
1
1.
This paper discusses the achievements and the unsolved problems of the first generation of Digital Circuit Multiplication Systems (DCMS) 1 DCMS is an abbreviation for Digital Circuit Multiplication Systems. DCME is an abbreviation for Digital Channel Multiplication Equipment. Both refer to the same technique of combining digital speech interpolation and low rate encoding. . The following summarizes proposed improvements in DCMS technology. A major improvement in DCMS gain may be achieved by implementation of facsimile demodulation. The design considerations of this technique are discussed. The CCITT activities on standardization of a 16 kb/s speech coding algorithm are reviewed. In order to adapt this algorithm to implementation in a DCMS, the operation of the algorithm has been modified to enable variable bit rate operation at rates between 12·8 and 24 kb/s. The implementation of such an algorithm in DCMS will further increase the overall compression gain. The first generation of DCMS has been implemented mainly on heavy traffic routes. A DCMS terminal which is optimized for operation on ‘thin’, or smaller, routes, using an IDR link operating at 512 kb/s, is described. Tandem operation of DCMS is becoming an increasingly important consideration on both international and national routes. The accumulation of qdu's (quantization distortion units) when two pairs of DCME/S terminals are operated in tandem can be avoided by an arrangement without ADPCM decoding/encoding in the transit terminals so that the ADPCM decoding is carried out only at the final destination DCMS terminal. 相似文献
2.
本文基于DSP芯片TMS320C6201提出了通过对简化G.728建议解码过程实现低复杂度的语音能量估算的算法。并成功地在TMS320C6201上进行了优化实现。 相似文献
3.
4.
5.
本文以G.728语音编码标准为基础,提出一个15.2kb/s LD-CELP语音编码算法。通过对滤形码书进行重新设计,降低了算法复杂性,同时保持高质合成语音。最后,用双片TMS320C31高速DSP系统全双工实时实现了该算法。 相似文献
6.
7.
8.
G.728标准将增益滤波器的偏移不适当地处理成常数32dB,相当于将20~30ms内短时平稳的语音信号不适当地按整个时间轴上的平稳信号对待。对增益滤波器的改进必然涉及优化混合窗。该文提出一种估计平均分段信噪比的方法用来设计混合窗参数,并导出激励增益的精确表示。以此为基础,将Jayant的自适应量化与G.728的增益预测结合起来,提出一种适合于设计低时延码激励线性预测(LD-CELP)的增益码书的方案。用此方法,激励的精确值经自适应预测和量化后,3bit自适应量化和4bit自适应量化分别比G.728的固定量化有0.5dB和6dB的信噪比的改善。当采用4bit自适应量化和64码字的波形码书,比G.728复杂性降低20%,同时信噪比提高1dB。 相似文献
1