A Novel ECT System Based on FPGA and DSP

Previous analogue designs have many associated problems such as noise, component mis-matching, input offset and so on, and their speed is limited by some factors such as switching transients, multiplexing overhead and conversion delays. To improve the precision and speed of the system, a novel 16-electrode digitized electrical capacitance tomography system based on field programmable gate array (FPGA) and digital signal processor (DSP) is designed. FPGA performs the system logical control, produces sine wave exciting signal and realizes digital demodulation, which greatly simplifies the control and interface circuit and improves the reliability of the system. While DSP accomplishes image reconstruction, then sends grey levels to host computer through PCI bus to display the cross section image. The results of theoretic analysis and experiment show that both systematic SNR and speed are improved effectively.