Study On Beamforming Techniques Based On Velocity Measurements

Beamforming technique is a sound source identification method based on the array signal processing. Its principle is using weighting and summing algorithm for the data received by microphone array to get the equivalent sound field distribution, so as to identify the sound source. Sound pressure is the input of the traditional beamforming techniques. However, the particle velocity is also an important acoustic quantity. In this thesis, the particle velocity is proposed to be used as the input of beamforming techniques and the beamforming techniques based on velocity measurements are proposed.Firstly, the basic principle of beamforming is introduced, including the theoretical algorithms of some typical beamforming techniques. By analyzing the velocity measurements methods, the beamforming techniques based on velocity measurements are given, and the validity of these methods are verified by numerical simulations. Meanwhile, spherical array which can capture the dates coming from every direction in once measurement is applied to this method. To prove the superiority of the proposed, numerical simulations are performed. Secondly, the deconvolution beamforming techniques are introduced. On the basis of those theories, the deconvolution beamforming techniques based on velocity measurements are given. The simulation results demonstrate that the proposed methods can achieve the same resolution as in the traditional deconvolution beamforming technique. Finally, in order to solve the problem that all sources must be confined on one side of the measurement in the traditional beamforming, on the basis of the plane wave assumption, a fast sound field separation method based on single layer pressure and velocity measurements is proposed. Meanwhile, it is applied to beamforming for identifying the sound source in the presence of backward disturbing sources. The simulation and experimental results demonstrate that the proposed method can remove the disturbance of the disturbing sources well, and it is especially applicable for utilization combined with beamforming.