基于FPGA实现直接数字频率合成脉冲线性调频信号

摘要

The principle and circuit configuration of direct digital synthesis(DDS)technology are introduced in this paper. The feasibility of linear frequency modulation(LFM)signal generation based on DDS technology(DDS⁃LFM)is discussed. Two circuit structures of generating phase⁃address signal based on DDS are offered. On this basis,the parameter setting of DDS⁃LFM system is analyzed. The hardware circuit of DDS⁃LFM system was designed by means of FPGA. The spectral analysis of wave⁃form data exported from the system was conducted with Matlab. As a result,curves of the normalization amplitude⁃frequency and time⁃frequency are given.%通过研究直接数字频率合成（DDS）技术的原理和电路结构，分析基于DDS技术合成脉冲线性调频信号（DDS⁃LFM）的可行性，给出两种DDS相位地址信号产生电路的原理结构。在此基础上分析DDS⁃LFM系统参数的设置问题，利用FPGA设计实现DDS⁃LFM系统的硬件电路。最后利用Matlab仿真软件对该系统输出的波形数据进行频谱分析，给出了归一化的幅频特性曲线和时频特性曲线。