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描述了欧洲全数字集群系统(TETRA)声码器中的ACELP算法、结构及其技术特点。采用Chebyshev多项式准确有效地估算线谱对(LSP);采用开环和闭环分析相结合进行非整数基音搜索;采用代数码本结构作为固定码本,大大降低了计算复杂度,在频域更好地控制了激励信号的统计特性。ACELP在低于4.8 kb/s的码率下能获得较好的语音质量。
Describes the ACELP algorithm, structure and technical features in the European Total Digital Trunking System (TETRA) vocoder. The Chebyshev polynomial is used to estimate line spectrum pair (LSP) accurately and effectively. Non-integer pitch search is performed by combining open-loop and closed-loop analysis. Using algebraic codebook structure as fixed codebook can greatly reduce computational complexity and improve frequency domain Control the statistical characteristics of the excitation signal. ACELP achieves better speech quality at a bit rate lower than 4.8 kb / s.