The Realization Of Communication System Based On The1.2K Melp Speech Coding Algrorithm

In the past ten years, digital communication field have an amazing development, and speech coding technology has great contribution to this development. The data after speech coding has several advantages like high reliable, strong ability to anti-interference, easy to check the error, smaller to store. And the low speed and high quality low speed speech coding technology is becoming the focus of the research, it is widely used in network communication, voice mail, IP telephone, secret communication, etc.Low speed speech compression algorithm is a subject with complicated computation and it has high complexity, and important realistic meaning.1.2k MELP algorithm is excellent in low rate of compression algorithm. It combined the theory of mixed excitation and advanced multiband excitation, made foundation of LPC model, and made some improvements in the absjects of Producing excitation signal and extracting pitch, and improved the quality of synthetic speech sound. These methods mainly include taking mixed incentive, using the periodic impulsive, using the residual harmonic spectrum processing technology,the adaptive enhancement technology and the pulse shaping filter.Firstly, this thesis studied the key technology of1.2k MELP voice compression algorithm, explained the coding and decoding of each step of the process in detail. Then using the Microsoft1.2k MELP source code" Microsoft Speech coder ANSI-C Source Code SC12001200BPS speech coder Version7" simulated the1.2k MELP simulation on PC to test it’s performance form the absjects of speech quality and time delay. The focus of this paper is the realization of the communication based on1.2k MELP, the system realized the series of processes of speech acquisition, speech coding, speech decoding, package transmission, voice broadcast. Proved by experiments, the system is easy to operate, and it has stable performance, good voice quality and small time delay.