The Design And Realization Of High-speed Synchronous / Asynchronous Hybrid Multiplexing Device

The transmission of audio and video data becomes more and more important in the space data transmission system with the development of space science. Audio and video data transmission has more requirement in isochronous quality and real-time. The speed of video data is high, and the volume is great. Conventional method is to transmit audio and video information in a single channel, but that will waste much resource, neither good for miniaturization and portability of the spaceflight equipment. Multiplexing audio, video and asynchronous data will improve the utilization ratio of the channel.In this article, The Consultative Committee for Space Data Systems(CCSDS) Advanced Orbiting Systems (AOS) report is applied to this kind of requirement above. Two-level multiplexing strategy and virtual channel schedule are suggested to satisfy the isochronous character of video, audio data transmission and the agility of asynchronous data transmission. Synchronous and asynchronous high rate multiplexer chip is designed base on FPGA device, this chip can multiplex one channel audio data, one channel video data and two channels asynchronous data, the transmission rate of multiplexer is 8Mbps. A demo system is built to validate the function of multiplexer, this demo system includes video and audio data send equipment, asynchronous data source, synchronous and asynchronous high rate multiplexer, data receive equipment. In the end, isochronous performance of the multiplexer is analyzed.The result of experiment indicates that synchronous and asynchronous high rate multiplexer can multiplex one channel audio data, one channel video data and two channels asynchronous data rightly, and the data format is according with the CCSDS AOS standard. The results are consistent with the theories.Erenow, rare people inland has try to research on the synchronous and asynchronous high rate multiplexer. The research in this program has great meaningfor the development of synchronous and asynchronous high rate multiplexer in the future spaceflight project.