该文介绍了基于多带激励(MBE) 语音模型的改进型800/920/1200bps 语音编码器。该编码器采用二级离散余弦变换编码方案对逐帧变化的谱幅度参数进行自适应动态量化编码，大大减小了编码比特率，使得800~1200bps速率的MBE语音编码器的实现成为可能。该文重点介绍二级离散余弦变换编码方案及DSP硬件实现。
An 800/920/1200bps modified speech coder based on the Multi-Band Excitation (MBE) speech model is presented. The two stage discrete cosine transformation coding scheme has been used to quantize the spectral magnitude parameters changing frame-by-frame adaptively in the speech coder. The coded bit rate of speech is largely reduced and that make it possible the implementation of 800~1200bps MBE speech coder. This paper focuses on the design of two stage discrete cosine transformation coding scheme and hardware implementation based on DSP processor.