Turbo Codes And Melp Codes In Voice Transmission

This paper research on Turbo code and MELP coder based on JSCC theory. Join the two codes can achieve a better performance than the traditional Tandem system.Through the study of the structure and parameters of Turbo code, some new methods were proposed. Focus on the corporation of the two codes, using the character and different important levels of the MELP bit stream can diminish the BER of the channel.After examining the quality of MELP compressed speech when transmitted over noisy communication channels in conjunction with Turbo code using a variety of error-control schemes such as unequal error protection (UEP), early detection, etc, some useful points were found. The correlation of parameters, different important levels and error correct codes can be used to low the probability of loss frame and to protect the more important bits.Simulation results, subjective test and objective test proved the correctness of several algorithms that joint source-channel coding applied to speech .And some new better methods are proposed.