Study On Dual-channel Active Control Of Noise

At present, problems caused by noise has attracted great attention. People often use octave control method in the field of sound, but the control accuracy is not very high. Aiming at solving the disadvantages, the theoretical and experimental study on the multiple shaker noise control system is presented in this paper. Based on multiple-input-multiple-output(MIMO)linear system theory, this thesis presents the control algorithm, theoretical analysis and testing research on the MIMO noise test control system.Use a sound card as the initial signal conversion device, MATLAB as the software platform to build a dual-channel active control system based on the VXI bus instrument in the laboratory. The test control system implements dual-channel excitation signal generation, the response signal collection, noise power spectrum density calculation, data processing and achieve to control noise power spectrum density. After a great deal of simulation and tests, the results indicate that this control system can basically meet the requirements of relevant standards.The time randomization method is used to generate the driving signals for noise test control in this paper. This is derived from traditional time domain randomization. The conventional discrete random phases by registers shifting method are replaced by the introducing continuous uniform distribution phases.The proposed method can produce high quality random signals and is convenient in the software programming.A method for the driving signals update by the difference between the reference spectra and control spectra is used. This is an effective control method for the frequency spectra equalization. By the algorithm the control spectrum can be converged to the reference smoothly,quickly and stably. The theories and algorithms mentioned above are verfied and corrected by lots of tests. The results of experiment show that the noise control system proported in the paper is satisfactory and practicable.