卫星数传VCM综合解调器关键技术研究

发布时间：2018-06-08 17:45

本文选题：VCM + 解调　；参考：《中国科学院大学(中国科学院国家空间科学中心)》2017年硕士论文

【摘要】：近年来有效载荷技术迅速发展,对卫星提出了更高精度的探测和通信任务需求,带来了数据传输能力需求的提升。在这样的背景下,为了提高通信链路的效率,VCM(variable coding modulation)技术应运而生,VCM系统在不同信道条件下采用不同的信道编码和调制方式,相比于传统的CCM(constant coding modulation)体制,更加充分地利用链路资源,在相同带宽和功率的条件下,实现更大的传输数据量。本文针对VCM技术的变调方式特点,参照DVB-S2的物理层帧结构,研究了VCM系统的综合解调器。主要研究内容如下:一、研究了PLS码解码,差分相关帧头检测器以及两种帧同步方案。两种帧同步方案分别基于阈值比较和窗搜索。通过仿真,对两种算法的性能和算法复杂度进行了比较,相对于阈值比较算法,窗搜索算法性能略好,但资源消耗更大。二、在对现有的最大似然、Kay、Fitz、LR、MM和Y.M.Jiang数据辅助型频偏估计算法仿真和分析的基础上,基于MM算法,采用对去调制信号自相关进行叠加的方法提升算法性能,能够在信噪比-2dB下,完成对20%符号速率频偏的估计。三、相位粗补偿基于最大似然,利用导频结构,通过线性插值的方式完成相位的粗补偿。其补偿后的相位抖动已接近无频偏、不进行相位补偿时的情况。
[Abstract]:In recent years, with the rapid development of payload technology, higher precision detection and communication missions are required for satellites, which leads to the improvement of data transmission capacity. In this context, in order to improve the efficiency of communication links and improve the efficiency of VCM variable coding, VCM systems adopt different channel coding and modulation methods under different channel conditions, compared with the traditional CCM constant coding modulation-based systems. Make full use of link resources and realize more data under the same bandwidth and power. According to the characteristics of the modulation mode of VCM technology and referring to the physical layer frame structure of DVB-S2, the integrated demodulator of VCM system is studied in this paper. The main contents are as follows: firstly, PLS decoding, differential correlation frame header detector and two frame synchronization schemes are studied. The two frame synchronization schemes are based on threshold comparison and window search, respectively. Through simulation, the performance and complexity of the two algorithms are compared. Compared with the threshold comparison algorithm, the window search algorithm has better performance, but more resource consumption. Secondly, on the basis of the simulation and analysis of the existing maximum likelihood Kayzan Fitzan LRNMM and Y.M.Jiang data aided frequency offset estimation algorithms, based on the MM algorithm, the method of superposing the de-modulated signal autocorrelation is used to improve the performance of the algorithm, and it can improve the performance of the algorithm under signal-to-noise ratio (SNR) -2dB. The 20% symbol rate frequency offset is estimated. Third, phase coarse compensation is based on maximum likelihood, and the phase coarse compensation is completed by linear interpolation using pilot structure. The phase jitter after compensation is close to that without frequency offset.
【学位授予单位】：中国科学院大学(中国科学院国家空间科学中心)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN763;TN927.2

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