Research Of Speech Coding In Voice Cipher Of Single-chip

Today traditional digital voice ciphers are being wildly used in governments and army. But these voice ciphers are quite low in the integration. So it is expensive to produce traditional voice ciphers quite a lot. If a whole voice cipher can be integrated into a single chip, the price of the voice cipher can be reduced quite a lot. That will be of great Significance. This thesis focuses on the research of high quality speech coding whose speed fits the voice cipher of single-chip. The design of the single-chip voice cipher is presented, based on studying the principle and whole structure of the traditional voice cipher. MELP speech coding algorithm is chosen to be used in voice cipher of single-chip. MELP is implemented on PC in C language and on TI's C54x DSP. This thesis proposes a method of voice data acquisition and storage on DSP, and the use of CCS to optimize the codes. A method of rewriting key codes in C54 assembly language is presented. The MELP algorithm in the voice cipher of single-chip is implemented successfully.