Multichannel capacitance tomograph for dynamic process imaging

The Division of Nuclear and Medical Electronics of Warsaw University of Technology is an institution where a capacitance process tomograph was first designed in Poland. The design of this capacitance tomograph, its performance and first results are presented in the paper. The tomograph can operate with one or two probes with up to 32 electrodes altogether. Twelve or sixteen electrode configurations is commonly used and a two times twelve or two times sixtheen electrode set up is provided for flowmeter applications. Additionally, the device has functionality of a 16-channel capacitance meter for industrial applications. The tomograph has a novel modular structure. It consists of 16 analogue signal cards, a motherboard and a control module with an analogue to digital converter. The measurement is based on a standard charge-discharge method. The signal card is capable to work both as a transmitter and a receiver during the measurement process. The motherboard provides communication between signal cards and the control module using a custom digital bus. The control module contains a 16-bit analogue to digital converter, a control logic, and a serial communication interface. All digital electronic circuits have been designed using programmable logic devices (PLDs).