Speech compression and echo cancellation algorithm development for digital communication systems
Chen, Xi, writer on electrical engineering
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With the development of DSP (Digital Signal Processing) technologies in the last two decades, more and more DSP applications systems have been used in telecommunication applications such as echo cancellation, and speech processing. This thesis provides two DSP algorithms: a new speech compression technique and a "Two- Echo-Path" model line echo cancellation system. The new approach of speech compression technique that can be used in communication systems such as voice mail, answering machines, and multimedia is introduced in Chapter 2. The goal of the new speech compression algorithm is to reduce the computation complexities of speech compression algorithms while keeping the processed speech quality reasonable. A VQ (Vector Quantization) technique, preemphasis, long-term prediction, and sampling rate conversions are used in this speech compression algorithm. The computer simulation in C programs and real-time implementation in TMS320C50 are presented as well. The echo cancellation system with the "Two-Echo-Path" model is introduced in this thesis both theoretically and practically. In this system, the details of the "Two-Echo- Path" are discussed by way of a comparison with the traditional method. An adaptive algorithm and some logical control rules are used to realize more robust and higher performance line echo cancellation. The computer simulation and real-time implementation with the TMS320C50 Digital Signal Processor (DSP) are presented.