Research On Beamforming Technology Based On Differential Microphone Arrays

Acoustic array technology originated in aviation early warning and military reconnaissance.The use of acoustic array beamforming technology to detect transformers,power grids and UHV transmission lines in electrical systems is currently a hot research topic.However,in view of the large volume of the acoustic array and the inconvenience of carrying,how to realize the miniaturization and portability of the acoustic array needs to be further solved.To this end,this paper studies the beamforming technology based on the differential microphone array,the specific work is as follows:(1)This paper introduces the far and near field signal model and microphone array topology,and focuses on the simulation of differential microphone array beamforming.The simulation results show that the traditional microphone array cannot form a beampattern with a constant frequency when processing wideband signals,while the Differential Array ensures that the beampattern is unchanged at both high and low frequencies.(2)Dealing with the problem of abnormal white noise gain(WNG)of the circular differential microphone array(CDMA),a beamforming design method based on the alternating direction multiplier method(ADMM)is proposed.The idea of this method is to construct a beamformer model based on the principle that the weight vector and signal direction of the beamformer are in the same direction and opposite to the interference signal and noise signal,so as to minimize the output power of the beam pattern in the direction of noise signal and interference signal.And convert it into a 1-norm optimization problem with constraints,and then use ADMM to transform it into multiple unconstrained optimization problems,and solve the weight vector iteratively to obtain the optimal output response of the array.Finally,the simulation results show that the ADMM method can effectively solved white noise gain abnormal.(3)Design the software and hardware system of the microphone array based on DSP.First,the DSP chip OMAP-L137 is used as the main chip to build a seven-element circular microphone array system which can change the number of array elements;then the DSP application program is compiled with CCS software compiling environment;finally,the performance of the beamforming method is verified in a large office.The experimental results show that the beamforming system can accurately locate the sound source and noise direction,achieve the expected results.