星载高速高阶QAM调制技术设计与实现

发布时间：2018-12-17 09:32

【摘要】：本文首先介绍了课题研究的背景及意义,对高阶调制在卫星宽带无线数据传输应用的意义进行说明。在简要介绍最常用的星载调制技术调制原理的基础上,针对8PSK、 16APSK、16QAM及32APSK调制原理及传输的理论进行了深入的对比研究,确定了以数字调制为核心的星载高阶调制技术总体方案。随后,以数字调制方案为基础,通过ADS软件进行了高阶调制解调的系统建模,主要以8PSK、16APSK、16QAM及32APSK调制器为主,结合卫星通信中AWGN信道的特点,针对系统中常见的的放大器非线性特性、调制的幅度不平衡特性、带内波动特性和相位噪声特性等几个的主要的特性指标对整个系统的影响进行了仿真和验证。本文对CCSDS提出的LDPC编码特性进行了仿真和分析,依据编码特性提出该编码的高速并行处理方法,并与8PSK、16APSK、16QAM及32APSK调制方式结合,搭建具备LDPC码的仿真系统,得出使用LDPC编码后,高阶调制系统的编码增益特性,对LDPC+APSK特性和LDPC+QAM的特性进行比对,得出结合不同高阶方式时系统通道特性的差异。结合无线信道的AWGN特性,通过系统建模,得出使用LDPC编码后,高阶调制传输系统中的放大器非线性特性、调制器的幅度不平衡特性、带内波动特性和相位噪声特性对传输效果的影响,为星载系统调制方式与编码方式的结合方案供理论依据。最后,对实际电路即Ka频段调制器的设计、组成和实现方法进行详细介绍,对关键指标进行了分解,并将实测结果与仿真结果进行比对,得出方案的正确性。
[Abstract]:In this paper, the background and significance of the research are introduced, and the significance of high-order modulation in satellite wideband wireless data transmission is explained. On the basis of a brief introduction of the modulation principle of the most commonly used spaceborne modulation technology, the modulation principle and transmission theory of 8PSK, 16APSKSK16QAM and 32APSK are compared. The overall scheme of spaceborne high order modulation with digital modulation as the core is determined. Then, based on the digital modulation scheme, the system modeling of high-order modulation and demodulation is carried out by ADS software. The system is mainly composed of 8PSK _ (16) APSKK _ (16QAM) and 32APSK modulator, combined with the characteristics of AWGN channel in satellite communication. The main characteristics of the system, such as the nonlinear characteristics of the amplifier, the amplitude imbalance of modulation, the in-band fluctuation and the phase noise, are simulated and verified. In this paper, the characteristics of LDPC coding proposed by CCSDS are simulated and analyzed. According to the coding characteristics, a high speed parallel processing method is proposed, and a simulation system with LDPC code is built by combining with 8PSKPK 16APSKK 16QAM and 32APSK modulation mode. The gain characteristics of high-order modulation system are obtained by using LDPC coding, and the characteristics of LDPC APSK and LDPC QAM are compared, and the differences of channel characteristics in combination with different high-order modes are obtained. Based on the AWGN characteristics of wireless channel and system modeling, the nonlinear characteristics of amplifier and amplitude imbalance of modulator in high-order modulation transmission system are obtained by using LDPC coding. The effect of in-band fluctuation and phase noise on the transmission effect provides a theoretical basis for the scheme of combining modulation mode and coding mode of spaceborne system. Finally, the design, composition and implementation method of the practical circuit, i.e., the Ka band modulator, are introduced in detail, the key indexes are decomposed, and the measured results are compared with the simulation results, and the correctness of the scheme is obtained.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.2;TN911.3

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