Audio Capture Card To Achieve The Study

Modern Communication System has been switched from analog signals transmission to digital signals transmission. Not only audio coding act as important part during the process of development .but also boost the development of the technology of hardware. How to realize audio coding in hardware system has become the very important research field.Vessel Audio Capture System is embedded system which is used for sampling the voice of sailor and VHF signal in operator cabin. And offer evidence for accident analysis precisely. At the present time, the similar production has already been in appliance phase in the domestic. Those production have distinctive for its individual properties.In order to satisfy the request of client, there are some innovation.1.Considering operator cabin's area, there are eighteen electret microphone distributing around the top of cabin. The hardware system sample six audio channel. It can decrease the area of PCB layout and increase the timing of data storage to 24 hours.2.Besides four speech channel which frequency range from 150 Hz to 3.4kHz ,there are two VHF audio signal channel with 6kHz. So, audio collecting and processing card can sample audio frequency range from 50 Hz to 6kHz with G.722.1 audio coding.3.To ensure of the real-time processing of signal in this design, DSP is used for the audio signal collecting and the algorithm of G.722.1 audio coding. Data storage and transmission are finished by FPGA , The communication between system and host done via PC104 bus. Data is storage in hard disk with file.4.The PC104 interface have favorable stabilization.The result shows that hardware system have achieve anticipated aim.