High-Precision Multi-frequency Electrical Impedance Tomograph

This book describes the design and architecture of §ACT 4, Rensselaer's 4th generation electrical §impedance tomograph. ACT 4 has a modular design that §can support up to 72 electrodes. The instrument is §able to apply either voltages or currents to all the §electrodes simultaneously and to measure the §resulting currents or voltages. ACT 4 is also able §to work with discrete excitation frequencies in the §range from 300 Hz to 1 MHz. To implement this high-§speed, high-precision, multi-channel instrument, the §analog electronics are augmented with a distributed §digital system, including a computer, Digital Signal §Processors (DSPs) and Field-Programmable Gate Arrays §(FPGAs).The overall system architecture is presented §as well as the implementation in FPGA firmware. §Experimental results are presented that validate §system performance. This book describes the design and architecture of §ACT 4, Rensselaer''s 4th generation electrical §impedance tomograph. ACT 4 has a modular design that §can support up to 72 electrodes. The instrument is §able to apply either voltages or currents to all the §electrodes simultaneously and to measure the §resulting currents or voltages. ACT 4 is also able §to work with discrete excitation frequencies in the §range from 300 Hz to 1 MHz. To implement this high-§speed, high-precision, multi-channel instrument, the §analog electronics are augmented with a distributed §digital system, including a computer, Digital Signal §Processors (DSPs) and Field-Programmable Gate Arrays §(FPGAs).The overall system architecture is presented §as well as the implementation in FPGA firmware. §Experimental results are presented that validate §system performance.