提升气象卫星高速数据解调性能的研究与试验

Research and Experiment on Improving Performance for High-Speed Data Demodulation of Meteorological Satellites

随着风云气象卫星事业的飞速发展,卫星观测通道数量不断增加、时间和空间分辨率不断提高,原始数据码速率已经由每秒几十兆比特上升为几百兆比特,不久将达到千兆以上。卫星的主要任务是获取遥感数据,从某种角度而言,卫星的价值等价于遥感数据的质量和大小。原始数据通过无线电载波传输至地面站,从载波中准确无误地解调出原始数据,是风云卫星观测系统最关键的环节,星地接口的核心,也是数据处理和服务的基础。为了提升解调性能,本文开展基于高速数字信号处理技术,设计数字解调的整体结构,分析载波恢复、交叉极化抵消、时钟恢复、均衡等关键模块的实现原理及方法。在实验室环境下,采用VHDL语言实现8PSK全数字解调系统设计,当采用7/8LDPC译码时,数据传输速率可达1.2 Gb/s,验证了所设计方案在高速数字信号处理方面的优越性和有效性,为风云卫星发展以及未来气象卫星中的调制解调提供依据。

With the rapid development of the Fengyun meteorological satellite project,the number of observation channels is increasing,and time and space resolution is enhanced.The original bit rate has been rising from tens of megabits per second to hundreds of megabits and soon will reach over gigabit.The main task of satellites is to obtain remote sensing data.From a certain point of view,satellites could be valued according to the quality and size of remote sensing data.The most crucial part of the Fengyun satellite observation system and satellite-earth-interface is transmitting original data to the ground station through the radio carrier and accurately demodulating the data from those carriers.And this is also the basis of data processing and services.In order to improve the demodulation performance,this article discusses the principle and method of realizing for following important modules:high-speed digital signal processing technologies,the designing of the overall structure of digital demodulation,and the analyses of carrier recovery,cross-polarization cancellation,clock recovery and equalization.Under laboratory conditions,8 PSK digital demodulation systems have been implemented using VHDL.While the data transmission rate reachs 1.2 Gb/s by adopting 7/8 LDPC decoding.And this strongly verifies the effectiveness and superiority of the design in high-speed digital signal processing.It also provides evidence for the development of the Fengyun satellite and the modulation/demodulation of meteorological satellites in the future.