【作者】 刘峰；

【导师】 潘明海；

【作者基本信息】 燕山大学 ， 通信与信息系统， 2006， 硕士

【摘要】 任意频谱信号发生器信号重构的实时性、数字正交调制器的高精度特性,都需要高性能的数字信号处理系统来实现。通过对分布式并行信号处理系统结构形式与实时性的分析,本文给出了两种基于PC机、多数字信号处理器(DSP)的分布式高速并行数字正交调制系统,其中基于数字信号处理算法或直接数字频率合成器(DDS)实现的数字正交调制系统与传统的线性正交调制方法相比都具有更高信噪比。基于DDS的数字正交调制方案是以AD9857为核心实现的。论文分析了上变频器(AD9857)的内部结构、工作原理。通过计算机仿真分析了AD9857所采用的基于级联积分梳状(CIC)滤波器的数字正交调制方法,以便于高效地实现基带信号的内插扩展和低通滤波。论文阐述了基于DDS的数字正交调制器硬件电路的实现原理与方法,开发了基于DDS的八通道并行数字正交调制系统。同时为了实现PC机与八通道数字正交调制器的高速数据交换,开发了基于EZ-USB FX2的USB2.0数据传输系统,最大限度地降低了PC机与数字信号处理系统间的电磁干扰,提高了信号处理系统内部数据传输速度及硬件系统的可靠性。完成了八通道数字正交调制系统硬件的初步设计与开发工作。论文还对基于DSP、通用串行总线(USB)、数模转换器(DAC)等电路的三通道数字正交调制器的硬件系统进行了设计与电路分析、功能测试试验(DSP系统、DAC系统与数据链路)、硬件系统主要性能指标测试与分析,其实际信号重构精度(信噪比)能达到65 dB以上,达到了国内先进水平。更多还原

【Abstract】 The real-time property of optional spectrum signal generator in signalreconstruction, the high precision characteristic of digital quadrature modulatormust be carried out by high-powered digital signal processing system. Based onthe analysis of different architectures and real-time properties of distributedparallel signal processing system, two kinds of distributed high-speed paralleldigital quadrature modulation system based on PC and multiple digital signalprocessors (DSP) are presented in this paper, of which the digital quadraturemodulators based on digital signal processing algorithm or direct digitalfrequency synthesizer (DDS) both possess higher ratio of signal to noise incontrast to the method of conventional linear digital quadrature modulation.AD9857 is the core of the digital quadrature modulator based on DDS. Theinternal structure and operating principle of the up-converter (AD9857) areanalyzed in this paper. In order to realize interpolation and low-pass filter highefficiently, the method of digital quadrature modulation based on cascadeintegral comb (CIC) filter used by AD9857 is analyzed by computer simulation.The hardware achieving principle and method of the digital quadraturemodulator is presented in this paper, and then the eight-channel parallel digitalquadrature modulation system based on DDS is developed. At the same time, inorder to realize high-speed data exchange between PC and the eight-channeldigital quadrature modulators, the USB2.0 data transfer system based onEZ-USB FX2 is developed in this paper, which reduces the electromagneticinterference between PC and digital signal processing system maximum,improves the reliability of the hardware system and the speed of data transfer inthe signal processing system. At last, the hardware design of the eight-channeldigital quadrature modulation system is achieved on the whole. The hardwaresystem of three-channel digital quadrature modulators based on DSP, universalserial bus (USB) and digital-analog convertor (DAC) is also designed andanalyzed in this paper, besides, the functions of the hardware system (DSPsystem, DAC system and data passage) are tested, eventually, the performanceof the hardware system is tested, and the actual signal reconstruction accuracy(SNR) is over 65dB, which reachs the domestic advanced level.更多还原