A Research On The Digital Voice Encryption System Based On Vocoder Technology

The HF/ VHF communications between coast and ships are mainly analogue in our country. With the development of MSA business and the need of mission expanding. Digital voice encryption system is safer, easier to implement, and cheaper than the traditional analogue encryption one. It overcomes the shortcoming which means difficult to achieve both the confidentiality and the quality in analogue encryption systems.Research work and design for HF/ VHF transcerivers in this paper are taken as follows:Firstly, through studying the character of shortwave & ultra-short wave voice communication and the principle of digital voice communication, a few forms of vocoder arithmetic-LPC and WI were analyzed and studied. The CMX618 based on RALCWI arithmetic was chosen as voice processing IC.Secondly, considering the resources and requirement of the system, Stream Ciphers was used in digital voice encryption system.Thirdly, hardware circuit and software framework were designed and debugged. An encryption prototype was accomplished.Lastly, an experiment on HF/ VHF digital voice communication between coast and ships, coast and coast was carried on. And the system was proved to be achieved the requirement designed.