47.5 U.S. Federal Standard MELP Vocoder Tactical Performance Enhancement via MAP Error Correction
نویسندگان
چکیده
The United States government has developed a new Federal Standard 2400 bps vocoding algorithm called MELP Mixed Excitation Linear Prediction [1]. This vocoder has very acceptable voice quality under benign error-free channel conditions. However, when subjected to high error conditions as could be experienced in tactical vehicular operations, amelioration techniques may be employed which take advantage of the underlying inter-frame residual redundancy of the MELP parameters themselves. This paper describes experiments conducted on the MELP vocoding algorithm in conjunction with Viterbi convolutional error decoding, and enhanced with Maximum A Posteriori techniques which utilize these redundancy statistics. Both hard and soft Viterbi decoding implementations are investigated in addition to Turbo codes.
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