Design And Implementation Of Digital Filter In ECT Data Acquisition System

Electrical capacitance tomography is also known as ECT. It is based on capacitance sensing principle of process tomography technology.It has many advantages such as fast response, low cost, safety, visual, non invasive. In the gas-liquid two phase flow void fraction measurement, two phase flow split phase content detection and flow pattern identification, image reconstruction algorithm, and many other fields, it is being applied more and more widely. The capacitance tomography system is mainly composed of three parts, which are capacitance sensing unit, data acquisition system and image reconstruction. Among them, the most critical one is data acquisition. In the data acquisition process, due to the interference of external and channel, collected signals tend to be a mixture of some noise, by using digital filtering techniques to weaken the signal to noise and interference, extract the final desired signal by the processing in the computer imaging.The in order to solve the problem of high frequency noise in electrical capacitance tomography data acquisition system, in analysis of ECT system data acquisition and control principle based, based on the theory of digital filter and FPGA technology design a digital filter with FPGA technology based on the combination of improved distributed algorithm FIR low-pass digital filter. The main work is as follows:1.In-depth study of the characteristics of ECT technology of data acquisition system, working principle and system structure, combined with the background and significance of the research, analysis of the current domestic and foreign development status and development trend, the digital filter of the ECT data acquisition system is of important significance in tomographic imaging technology that based on.2.Through the digital filter design basis and principle analysis, with the structure of FIR digital filter based on the difference in the structure were classification research, and has carried on the comparative analysis to the FIR digital filters commonly used window function design method, for the digital filter to provide a theoretical basis for design.3.Principle and characteristics of distributed sort algorithm, for realization of distributed algorithms for the digital filter of different types of processing speed, resource consumption and other aspects of the detailed analysis, and finally puts forward optimized improvement structure based on traditional distributed algorithms.4. The dissertation studied the principle and characteristics of the distributed algorithm. Analyzed the different types of distributed algorithm's processing speed, resource utilization, etc. Finally we put forward the improved structure optimization which is based on the traditional distributed algorithm.5. Setting a sampling frequency is 1.5MHz, pass band cutoff frequency of 20MHz FIR digital filter design examples, selection window function design method, extraction and quantification of the filter coefficients using FDATool toolbox in MATLAB, at last, the simulation of examples using that. Experiments show that the Ming the designed filter error is in the allowed range, and the filtering effect is obvious.