直接数字式频率合成(DDS)作为一种新的频率合成技术，它可以实现从信号参数到信号波形的转换。在传统的线性调频连续波雷达测距系统中，通过三角波发生器对压控振荡源(VCO)进行调制，输出线性调频连续波雷达(LFM-CW)信号，但是压控振荡源的扫频非线性以及很低的频率分辨率对LFM-CW雷达的测距精度产生很大的影响。文中将直接数字式频率合成技术引入LFM-CW雷达，代替压控振荡源，很好的解决了该问题。FFT频谱分析用DSP实现，系统控制用单片机完成，终端采用液晶显示。

Direct digital synthesizer (DDS) is a kind of ne w frequency synthesizer technique. With it signal parameter can be switched int o signal wave. In the field of traditional linear FM-CW ranging, voltage contro lled oscillator(VCO) is modulated by triangle wave and outputs linear FM-CW sig nal, but the sweep nonlinearity and low frequency resolution of voltage controll ed oscillator(VCO) make great influence to the range precision of linear FM-CW radar. In this paper, the direct digital synthesizer(DDS) is used in linear FM- CW radar instead of voltage controlled oscillator, the problem is solved well. F FT algorithm is realized by DSP, and the system is controlled by singlechip and the terminal uses liquid crystal display(LCD).

TN958