To solve the problem that traditional instruments are cumbersome to carry and that traditional experimental teaching is limited by time, space and the lack of instruments, a method which combines Field Programmable Gate Array (FPGA) and Flex technology to realize the remote virtual frequency sweeper is proposed . The overall framework of the system and the software and hardware structure are introduced. In the hardware part, the advanced RISC Machine ( ARM ) and FPGA is used to be the control center and the Direct Digital Frequency Synthesizer (DDS) technology is adopted to generate sweeping frequency signal source. The software development platform is based on Flex which support the development and deployment of Rich Internet Application (RIA). And the software design procedure is elaborated. Based on the Browser/Server ( B/S) structure , the system can realize realtime operation, getting real measured data and real time display from remote network. The results of example test indicate that this system can realize the functions of traditional frequency sweeper, the frequency resolution of the signal source can reach 0. 093 Hz, and the frequency range is from 0. 093 Hz to 1 MHz, which can test the amplitude - frequency characteristic of linear time invariant system directly and draw amplitude - frequency curve relatively.%为解决传统仪器携带不便以及传统实验教学受时间、空间、仪器不足等限制的问题,将FPGA和Flex技术相结合,提出了一种实现远程虚拟扫频仪的设计方法.介绍了系统的总体框架以及软硬件结构.硬件部分以ARM和FPGA为控制中心,采用直接数字频率合成技术产生扫频信号源.软件部分以支持富因特网应用开发和部署的Flex为开发平台,阐述了软件设计流程.该系统基于B/S架构,可实现远程网络实时操作、实测数据、实时显示.实测结果表明,系统实现了传统扫频仪的功能,产生的扫频信号源频率分辨率可达到0.093 Hz,频率范围为0.093 Hz到1 MHz.能直观测试线性时不变系统的幅频特性并绘制相应的幅频曲线.
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