中文摘要：

根据直接数字频率合成（DDS）原理,结合虚拟仪器平台提供的丰富软硬件资源,利用软件分段计算产生波形数据,通过数据采集卡（PC-DAQ）输出,输出信号频率分辨率高;频率跳变速度快;频谱纯度高.文中分析了虚拟信号发生器的各项性能指标,比较了其输出频谱与传统DDS输出的差异,最后给出了实验结果.该信号发生器已成功用作虚拟压电参数测量系统中的信号源.

英文摘要：

Based on the principle of DDS frequency synthesis, this paper introduces a virture signal generator which generates generates waveform data with software calculation on the virtual instrument platform and outputs signals by PC-DAQ with many advantages, such as high and changeable frequency resolution, short frequency-transition time and the pure spectrum. The difference of the virtual and traditional signal generator about output spectrum is compared. At last, the performance parameter of the signal generator and the experiment results are given. The virtual signal generator has been used as signal resource of piezoelectric parameter measurement system.