The Study Of The Voice Coding Arithmetic In GSM System And RPE-LTP System On DSP

In recent decades, the technology of the speech code is developed very fast. With the rapid development of DSP technology, it becomes a powerful tool in the speech signal processing, which makes it possible to implement all kinds of complex algorithms in real time. Based on different applications, many standards of speech compress coding have been established by different international standardization orgnizations. Thereinto, RPE-LTP voice coding arithmetic is presented by voice coding expert group, which is constituted by the scientists from England, Finland, Germany, France, Italy, Holand, Norway and Sweden. The voice coding expert group chooses 6 schemes from 20 and tests them. Finally, they formulate the Regular Pulse Excitement-Long Time Predictive with 13kbit/s encoding speed based on MPE-LTP and RPE-LTP.With the great progresses and a series of break-through in VLSI technologies, integrated DSPs came out soon after. Itegrated DSPs possess many advantages, such as compactness, low power cost, and high working speed and so on, which are mostly suitable in speech signal compressing. Present DSPs are getting more and more attentions in the information field, due to its powerful signal processing ability, becoming a hot-point technique in communication and other relating signal processing areas.This paper firstly describes the present speech compress coding technologies and standards. And the speech compress coding standards RPE-LTP is introduced. Secondly, the algorithm principles of RPE-LTP are studied, and the implementation process of RPE-LTP algorithm is analyzed deeply. Structures and properties of TI fix-point DSP are analyzed. Finally, the RPE-LTP encoder is implemented.(1) Hardware platform design, this article mainly completes the portion design of DSP, completes the circuit principium chart of DSP and PCB figure.(2) Several kinds of the most important technology of the speech code have been introduced in this paper, for instance: Short Time Process, Linear Predition Analyse, Vector Quantization, and Analyse by Synthesize, etc.(3) The RPE-LTP encdoer is partially implemented on TMS320C5409 in real time in C language. In the implementation process, several issues are analyzed and optimized, which include assignment of memories, selection of instructions, expansion of functions, selection of address modes and use of registers, etc.The test results show that the encoder can be applied in the realms requiring low delay such as multi-channel telecommunications.