Research On Underwater Single Side Band Voice Communications Systems

With the development of modern military and the improvement of utilizing and developing the resource of the sea, the research on underwater voice communications is getting more and more important. The underwater acoustic communications channel has characteristics of the bandwidth-limited, high temporal and spatial variability. We need to find an appropriate way to communicate under the underwater acoustic channel. The Single Side Band (SSB) which can save the frequency bandwidth, save the power and receive little effect from the channel condition is a pretty choice. Before digital communication was used in underwater communication, most of all ways of communication were SSB systems. Traditional SSB system was analogue, it was difficult to realize, and it always too big to be moved and test. But if we can realize SSB communication with digital way, we can not only solve these problems, but also encrypt and analyze this digital signal, it is kill two birds with one stone. Because of these, we made the SSB voice communication system digital, and researched a digital SSB voice communication system, which realized real-time underwater SSB voice communications with a good quality.There are three ways of SSB modulate. By way of choosing an appropriate way, I analyzed these three ways in detail, and finally decided to adopt the "filter way" as the way of SSB modulate. I used the A/D on sound blaster to make the voice digital, used API functions such as "waveInopen", "waveOutOpen" to control the sound blaster sampling and playing the voice signal, and used the buffers switching to realize the real-time voice communication.To make the underwater SSB voice communication system more practical, I replanted the system into the Vx Works embedded operating system, made the real time voice communication miniaturization. Fist of all, this thesis introduced the design of Vx Works devices driver, and then analyzed the device driver and...