【作者】 胡俊杰；

【导师】 陈晓敏； 熊蔚明；

【作者基本信息】 中国科学院研究生院（空间科学与应用研究中心） ， 计算机应用技术， 2011， 博士

【摘要】 随着国内外遥感卫星和各种有效载荷技术的迅速发展,遥感卫星所获取的数据量突飞猛进,目前卫星对地数据传输系统的主流调制方式BPSK、QPSK越来越无法满足卫星高速数据传输的要求,以16-QAM为代表的高阶调制方式将逐步在卫星数据传输系统中得到应用。本文面向卫星数据传输高速调制器的设计要求,运用现代数字信号处理技术并充分利用可编程逻辑器件以及各种高速硬件资源,设计实现了高速数字成形滤波器和射频功率放大器线性化数字预失真器,这两种技术应用在16-QAM卫星数据传输高速调制器的基带信号处理部分,对提高卫星高速数据传输的频谱利用率和功率利用率起到至关重要的作用,为下一步数字化卫星数据传输系统的实现奠定基础。首先,论文完成了800Mbps的16-QAM高速数字成形滤波器的设计和实现,主要技术指标达到国内领先水平。在进行数字成形滤波器设计时,提供了一套FIR成形滤波器主要参数选取的依据和方法,从硬件系统的运行速度、计算量、复杂度以及滤波后信号的质量、频谱特性、系统的误码率性能等各个方面加以分析和仿真验证。为了突破数字成形滤波器高速实现的瓶颈,提出一种基于多相滤波器结构与并行查找表相结合的滤波器实现结构,将滤波器的系数与调制方式码型映射相结合形成查找表,省去硬件乘法运算,提高计算速度,最后通过并行电路结构及高速电路技术实现了800Mbps的16-QAM高速数字成形滤波器原理样机。并且设计了一种基于双高速多路复接数模转换器的高速逻辑时钟同步电路,解决了高速成形滤波器设计中I/Q两路输出数据同步的问题。其次,详细研究了射频功率放大器数字预失真线性化技术,提出了一种查找表数字预失真算法的实现方案,搭建仿真模型进行验证,并针对一款星载数据传输应用中的2.3GHz SSPA高功率放大器,以XtremeDSP Development Kit-IV开发板为主要实现平台,编写VHDL程序语言下载到核心芯片Virtex?-4 FPGA中,搭建系统的实现与测试平台,设计实现了数字预失真器,通过验证该预失真器可以降低双音信号的互调失真功率达11dB,大大提高了射频功放的线性化水平。最后,以16-QAM卫星数据传输高速调制系统的设计为研究的出发点,全面系统地将高速数字成形滤波器和射频功放数字预失真器两项技术融入到系统的设计当中,运用MATLAB中的动态仿真工具SIMULINK搭建系统仿真模型,通过分析时域波形、星座图、误码率等方面充分论证了系统实现的正确性、有效性和可行性。并且针对16-QAM高速调制器的实现结构,推导设计了基于正交结构的射频功率放大器数字预失真器,通过仿真验证该方法能够简化系统设计并有效地改善功放非线性失真,该算法对于正交结构调制系统的设计具有重要的理论意义和实践价值。更多还原

【Abstract】 With the rapid development of domestic and foreign remote sensing satellites and payload technology, data obtained by remote sensing satellite leaps and bounds. Therefore, the mainstream modulation, BPSK or QPSK, in the current satellite data transmission system is increasingly unable to meet the requirements of the satellite high-speed data transmission. The 16-QAM modulation representing for the high-level modulation has gradually been applied in the satellite high-speed data transmission system. This paper faces the design requirements of high-speed modulator in satellite data transmission system, uses the modern digital signal processing technology and makes full use of programmable logic devices and various high-speed hardware resources, finally, achievly designs and implements high-speed digital pulse-shaping filter and digital predistorter for RF power amplifier linearization. These two kinds of technology have been used in the baseband signal processing part of 16-QAM high-speed modulator in satellite data transmission system. As a result, they have not only significantly improved the spectrum utilization ratio and power efficiency of satellite data transmission system, but also laid the foundation for digital satellite data transmission system realization in future.First of all, the thesis has completed design and implementation of 800Mbps 16-QAM high-speed digital pulse-shaping filter, and the main technical indicators have reached domestic advanced level. During design of digital pulse-shaping filter, basis and method of selecting the FIR main parameter have been provided. Various aspects including hardware system speed, computation complexity, quality of filtered signals, spectral characteristic and the system BER performance have been analyzed and validated by simulation. In order to solve the bottleneck of high-speed digital shaping filter implementation, multi-phase filter structure and parallel look-up table have been proposed. Filter coefficients and symbol mapping in modulation method have been combined to form look-up table. Thus, it saved hardware multiplication and improved the hardware computational speed. Finally the principle prototype of Abstract 800Mbps high speed digital 16-QAM pulse-shaping filter has been implemented through parallel circuit structure and high-speed circuit technology.Secondly, predistortion linearization technique on digital RF power amplifier has been detailed studied. The thesis proposes a look-up table algorithm of digital predistortion and builds simulation model to validate it. Digital predistorter has been implemented according to a 2.3 GHz SSPA high power amplifier which is just applied to satellite data transmission system. The XtremeDSP Development Kit-IV Development board is used as mainly platform on which VHDL programming language is downloaded to the core chip Virtex?-4 FPGA. Through verification the predistorter can reduce intermodulation distortion of two-tone signal to 11dB, and greatly improve the RF power amplifier linearization level.Finally, 16-QAM high-speed modulator design in satellite data transmission system is studied, and the two technologies of high-speed digital shaping filter and RF power amplifier digital predistortion have been comprehensively and systematically implemented into the system. The dynamic simulation tool MATLAB/ SIMULINK has been used to build simulation model. Through analyzing the time domain waveform, constellation chart and BER performance, system has been sufficiently demonstrated correct, effective and feasible. In addition, according to the realization structure of 16-QAM high-speed modulator, RF power amplifier digital predistorter based on orthogonal structure has been formulated and designed. Through simulation test this method can effectively simplyfy system design and correct power amplifier nonlinear distortion. The algorithm for nonlinear distortion of orthogonal structure modulation system design has important theoretical significance and practical value.更多还原