中文摘要：

为了提高电磁层析成像（EMT）系统的性能，设计了一套基于FPGA的EMT系统．DDS模块、数字解调模块、MCU控制模块、DA接口模块、AD接口模块和USB通信模块均集成在一块FPGA芯片中分析了激励频率、采样频率和MACIP核累加点数3者对解调过程的误差的影响，提出了通用的设计原则．通过信噪比实验对系统进行了评价和激励频率的优选，采用基于截断奇异值的反投影法获得不同分布的重建图像，其成像速度达到了27帧／s．高度的集成化提高了系统的稳定性，降低了调试难度．该系统设计方案也可以移植到EIT、ECT和ERT系统．

英文摘要：

An electromagnetic tomography （EMT） system based on FPGA is designed in order to improve the system performance. DDS module, digital demodulation module, MCU control module, DA interface module, AD interface module and USB communication module are integrated in one FPGA chip. The influence of excitation signal frequency, sampling frequency and accumulation number of the MAC IP core on demodulation is analyzed, and a gen- eral principle is proposed in this paper. The system is evaluated and an optimal frequency of excitation signal is se- lected based on the experimental analysis of signal noise ratio. A back-projection algorithm based on truncated singular value is selected to reconstruct different distribution, and the speed of reconstruction reaches 27 frame/s. High integration increases the system stability and decreases the difficulty of debugging. The system design proposed in this paper can be applied to EIT, ECT and ERT systems.