基于AD985的便携式数字扫频仪器的设计硬件设计.docVIP

基于AD9851的便携式数字扫频仪器的设计 (硬件设计) Design of portable digital based on AD9851 sweep frequency instrument (hardware design) 摘 要 关键词 扫频仪 DDS技术 增益控制 Abstract Sweep generator is an instrument for measuring transmission characteristics of the network. In this paper, the working principle of sweep generator were analysed emphatically, then a design scheme based on DDS technology were put forward. After analysing the research status of the sweep generators in the market and the system characteristics, we make sure the performance index and general scheme. In this design, the sweep generator consists of several parts, they respectively are swept signal generator circuit, gain control circuit, automatic voltage control circuit，detecting head output circuit，atmega128 microcontroller,power module circuit In which swept signal generator adopt the pure digital technique which has high-speed frequency conversion time, extremely high frequency resolution, lower phase noise and the outstanding advantage of programe control, super add the gain control circuit and Automatic voltage control circuit, the sweep generator can adapt to various test requirements. Embedded microprocessor AD9851 we re used as the control and processing and the compositive magnitude and phase detecting circuit LCD 192X64make the design of sweep generator more simple, the debugging more convenient and the performance more stable and reliable. In addition, this sweep generator can make stepping measurementautomatically in the whole frequency range. We can preset measuring range and stepping frequency, so the detailed frequency characterist ic curves can be seen clearly. This function brings users much convenience. Key words: sweep generator DDS techonology gain control  目录 摘 要 I Abstract II 第一章 绪论 1 1.1 扫频仪简介 1 1.2 扫频仪的分类及其简介 2 第二章 便携式扫频仪器方案的选择 7 2.1扫频仪基本知识 7 2.1.1扫频仪的功能与用途 7 2.1.2基本测量原理 7 2.2 系统的主要性能指标 8 2.3 总体方案设计与论证 9 2.3.1 方案一介绍 9 2.3.2 方案二介绍 9 2.4方案比较 10 2.5 总体方案确立 11 第三章 单元电路设计与分析 12 3.