Design And Implementation Of Low Bit Rate Real-time Speech Secure Communication Based On DSP

The speech secure communication is a kind of communication method that keeps the speech contents from burglarize to hear, it have the biggest practical value on the military and businesses. .The data encrypts is important means in the speech secure communication. Moreover, the bandwidth is a very limited and precious resource. And the low code rate speech codes is one of the important methods to be economical bandwidth. The DSP( digital signal processor) is an appropriation microprocessor that is applicable to the numerical signal processing, can carry out the speech compression quickly and availably to encrypt the speech.This system be with the low bit rate speech code and datas encryption for background, take the numerical signal processing technique as to carry out the means, take DSP as processor, how guarantee that the safety of the speech information again at the time of ecomonic bandwidth,put forward again a project, of low bit rate speech secure communication based on the TMS320VC5509A DSP.For guaranteeing the good sound at the time of economical bandwidth, the system adopts the algorithm of MELP of the 2.4kbps, and aim at the TMS320VC5509A hardware characteristic to optimize the realization of the MELP algorithm in assemble language. For the sake of the safety that the assurance speech correspond, the system adopts AES algorithm to encrypt the compression speech signal,because of good efficiency and good safety .The key consultation adopts Differ- Hellman agreement. Because the adoption DSP realization and software module design,the system has to expand goodly,can replace the speech compression to code algorithm and encrypt algorithm,so the system can be the low bit rate speech again the solid hour keeps secret the experiment terrace of the communication.Finally the system carried on the test. as the result is satisfaction; basic come to the design request.