An improved design method of CVSD coder and decoder

CVSD coding is widely used in the field of speech communication in military wireless, satellite, underwater and other complex environments for its simple implementation and strong error correction ability. However, the hybrid double integral delta modulation system with standard CVSD coding is unstable. In the face of channel burst error, the lack of anti-interference ability easily leads to the degradation of speech quality. An improved CVSD coder and decoder is designed. Based on the delay of speech coding and the correlation of speech data, the error measurement is carried out by continuously tracking multiple paths, and the optimal output sequence is found from a variety of possible coding outputs by using appropriate distortion criteria. The instability of the hybrid double integral delta modulation system can be solved. At the same time, the improved digital diffuser is used to improve the signal-to-noise ratio of coding and decoding, solve the error accumulation problem introduced by table lookup method, and further improve the adaptability of CVSD coding in special channels. Finally, the usability of the improved CVSD compiler is tested and evaluated based on an underwater voice communication terminal. The experimental results show that the improved CVSD encoder and decoder has stronger error resistance and better speech quality than the standard CVSD encoder in terms of stability, and has higher application and promotion value.