Spectrum Correcting Technology In Dynamic Signal Analysis And Software System

Spectrum correcting technology in dynamic signal analysis and software system are presented in this thesis. The study is based on the project of National Natural Science Fund of China and the State Ministry of Education of China, which deeply research on spectrum correcting technology in dynamic signal analysis and developing dynamic signal analysis virtual instrument software system.In order to avoid spectrum error due to energy leakage, the thesis research on identification of parameters of two close frequency components in discrete spectrum analysis, and simulation result shows the validity of the method. After analysising three existed methods for phase difference correction on discrete spectrum, it is recommended to correct the spectrum containing small noise in engineer practice by the first phase difference correcting method (performing FFT analysis on two continuous original sequence) with Harming window. Study shows that the basic principles of three existed methods for phase difference correction on discrete spectrum are identical, by which the twice FFT analysis through time-domain shifting time series or changing window's length is performed, and the spectrum by making use of the phase difference of two corresponding peak lines are finally corrected. Consequently, a synthesized method is presented in this thesis, which includes time-domain shifting ,window-length changing and window-type changing (the second time-domain sequence lags behind the first one with L points, performing N-point FFT analysis on the first sequence and M-point FFT analysis on the second one with different windows, and finally correcting peak lines). The simulation result shows that the synthesized method is easily implemented with high precision, which is also applicable for all kinds of symmetrical window function and having high ability of anti-noise.This thesis also study on the method of high speed data acquisition based on windows98, mixed programming by Visual C++ & Matlab and Visual Basic & Matlab. Adopting the latest research result on dynamic signal discrete spectrum analysis and the idea of virtual instrument, a dynamic signal analysis virtual instrument software system is developed, which is based on windows and has good performance.