【作者】 冯朝军；

【导师】 汪晓宁；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2007， 硕士

【摘要】 直接数字频率合成器(DDS—Direct Digital Synthesis)是一种全数字化的频率合成器，由相位累加器、波形ROM，D／A转换器和低通滤波器构成，DDS技术具有频率分辨率高、频率切换速度快、频率切换时相位连续、输出相位噪声低和可以产生任意波形等优点。随着数字电路和微电子技术的发展，DDS技术日益显露出它的优越性。目前，DDS技术已经在雷达、通信、电子对抗和仪器仪表等领域得到了十分广泛的应用。本文主要讨论了直接数字频率合成技术及其应用，并且通过软件仿真和硬件实现的方式对直接数字频率合成技术进行了研究。本文首先论述了频率合成技术的发展，比较了各种频率合成技术的特点，并介绍了直接数字频率合成技术的现状和发展趋势。然后介绍了Altera公司的DSP Builder仿真工具，DSP Builder是Altera公司推出的一个面向DSP开发的系统级工具，作为Matlab／Simulink中的一个工具箱出现。本文在DSP Builder环境下搭建了DDS模型以及仿真平台，并在DDS的基础上完成了ASK，FSK，2PSK调制的仿真实现。接着又介绍了TI公司生产的DSP处理器TMS320VC5402以及ADI公司生产的DDS芯片AD9835，并设计完成了基于DSP处理器TMS320VC5402的直接数字频率合成器的试验板，对试验板的存储器模块、CPLD模块、DDS模块、电源和时钟模块作了详细介绍。在软件方面，详细说明了CMD和中断向量表的编写方法。完成了DDS驱动程序的调试，实现了0～25MHz正弦波产生，FSK，2PSK，QPSK调制实现。针对DDS芯片的输出具有大量的谐波分量和系统时钟干扰，本文还设计了一种7阶椭圆低通滤波器，能较好地滤除谐波分量和系统时钟的干扰。论文的最后给出系统硬件调试以及DDS模块的调试结果。更多还原

【Abstract】 The Direct Digital Frequency Synthesizer is a kind of fully digitized frequency synthesizer, which consists of the phase accumulator, the sine look-up table, the digital to analog converter and the low band filter. It has high frequency resolution, fast frequency switching speed, low phase noise, the ability to switch frequencies while maintaining constant phase, and the ability to producing arbitrary waveforms. DDS has shown its advantages increasingly along with the development of microelectronics technique. Now it has been widely used in the fields of radar, communication, apparatus, etc.This thesis mainly discusses the direct digital frequency synthesis technique and its applications. Through software simulation and realization of hardware board, this thesis accomplishes an in-depth study of the direct digital frequency synthesis technique.Firstly, the thesis discusses the development of frequency synthesis techniques, compares the features of various frequency synthesis methods,discusses actuality and development trends of DDS. Then the thesis introduces the DSP Builder simulation tool of Altera first. DSP Builder is a system-level tool faced to the DSP development, as a toolbox of Matlab. This thesis builds a DDS model under DSP Builder environment and finishes simulation. Based on the DDS, the ASK, FSK, 2PSK modulation simulation are also completed. Then DSP processors TMS320VC5402 of TI and DDS chip AD9835 of ADI are introduced. A direct digital synthesizer board based on DSP has successfully designed and the memory, CPLD, DDS, power, and clock module are discussed in detailed. Based on this board, this thesis focuses on how to program the CMD files and vector table files. Then finishes the driver debugging of DDS, a sinusoidal of 0～25MHz,FSK,2PSK,QPSK Modulation. Because the output of DDS chip have a lot of harmonic components and systems clock interference, this thesis also designs a 7-order elliptic low pass filter which can be used to filter harmonic interference and the system clock. Finally, the hardware testing and DDS module debugging results are given.更多还原