【作者】 马年磊；

【导师】 沈保锁；

【作者基本信息】 天津大学 ， 通信与信息系统， 2004， 硕士

【摘要】 差分跳频技术是一种新型的跳频通信技术，它利用跳变的载波之间的相关性来传送信息。差分跳频技术应用于短波通信，可以在短波波段内实现宽频带、高速率的跳频，极大的提高了短波通信的数据速率，抗干扰、抗多径衰落能力，这种新型短波跳频系统将成为短波通信领域今后发展方向之一。直接数字频率合成(DDS)是继直接式和锁相式频率合成技术之后的新一代频率合成技术。它是一种在数字域中产生和处理正弦波形或其它连续波形的数字技术；对于要求高速跳频、输出相位控制和优良相位噪声性能的应用是首选的技术。本文重点论述了DDS的工作原理、基本结构和输出频谱，分析了DDS输出频谱杂散的主要来源：相位截断误差、幅度量化误差、以及DAC非线性误差，并提出了减少杂散的方法。跳频速度是决定整个跳频系统性能的主要参数。快速跳频频率合成器就成为跳频通信系统的关键。本文给出了提高锁相环频率合成锁定速度的方法，以及DDS的频率扩展方法，提出了适合短波差分跳频的频率合成器的独特设计方案。最后，本文完成了基于DDS+DSP的短波差分跳频频率合成器的设计。采用ADI公司的新型高时钟DDS芯片AD9852作为频率合成器，TI公司的高性能DSP芯片TMS320C6201作为高速控制电路，同时DSP完成跳频图案的产生。主要内容包括DSP与DDS的接口设计，滤波器的设计，以及其他主要电路的设计等。本方案通过电路试验，达到了很高的跳频速度，高的频谱纯度，完全符合差分跳频的设计要求。更多还原

【Abstract】 Differential Frequency Hopping (DFH) is a new type of frequency hopping (FH) communication technique. Its feature is the different method of carrying information with traditional FH technique. DFH transmits information by the correlation between hopping frequency carriers. When DFH is applied to HF communication, HF radio can achieve desirable performance of high hopping rate within a wide HF band, which will improve the data rate and capabilities of anti-jamming and anti multipath fading. This type of FH system will be the one of directions of future HF communication.Direct Digital Synthesis (DDS) is a new generation of frequency synthesis after Direct Synthesis (DS) and PLL frequency synthesis. DDS is a technique for using digital data processing blocks as a means to generate a frequency- and phase- tunable sine wave or other continuous waveform. It’s the preferred technique for applications requiring high hopping rate and excellent phase noise performance. In this paper, we make a systemic research on DDS technique. The structure, basic principle and frequency spectrum are discussed in detail. As spur is the key reason limiting DDS’s application, we analyze three factors impact spectrum of DDS, and give the solutions to decrease the spur.Hopping rate is the key parameter that determines performance of FH system, so fast FH synthesizer becomes very important. Several design schemes are discussed in this paper, including methods of improving locking speed of PLL and getting higher frequency from DDS. By comparison, a new scheme is put forward.In the last part, the scheme of DFH HF synthesizer is described. DDS chip AD9852 is selected as synthesizer, and TI’s DSP chip TMS320C6201 is selected as controller. Interfaces between DSP and DDS, and other key circuit are discussed in detail. By practical circuit experiment, the design realizes high hopping rate, and pure spectrum, completely meets design requirements.更多还原