Research And Realization Of MELP Vocoder Algorithm Based On Digital Radio

As the overall digital transformation in communication systems, analog radio also accelerated the transitional process to digital radio. In the field of private network communication, digital radio is gradually replacing analog radio with its strong advantages. Various international manufacturers in digital intercom have joined the digital radio research, to jointly promote the development of digital radio. Meanwhile, the voice operation as one of the leading business in any communication system, speech coding technology has also become the core technology of each one communication system. In digital radio, the research and design of voice coder algorithm is also the core portion. In this paper, based on DPMR (Digital Private Mobile Radio) and DMR (Digital Mobile Radio) standard, the MELP (Mixed Excitation Linear Prediction) vocoder algorithm is applied to digital radio. And also we have studied the research and realization of MELP vocoder.Firstly, the paper analyzes the development of digital radio, while briefly introduces the mainstream standard protocol of the digital radio. At the same time, conducts a basic introduction for speech coding.Secondly, this article detailedly discusses the analysis basis of MELP vocoder algorithm. Based on the speech digital model, we have studied the LP (linear prediction) analysis. The paper proposes the method for solving the LP parameters in the algorithm, and derives the transformation algorithm for seeking LSF (Line spectrum Frequency) parameters.Finally, the paper presents the design and implementation of MELP vocoder algorithm. We have thoroughly analyzed the MELP algorithm, and obtained the parameters of analysis voice by building the MATLAB simulaton model. And also we use the standard C language program achieve this algorithm. Then test the synthesized speech with the PESQ (Perceptual evaluation of speech quality) and get the objective MOS score. And the method of optimizing the algorithm is given. At the end, on the basis of the algorithm an improved algorithm is presented which is based on DMR standard protocol, and by verifying, the improved algorithm is feasible.