Research On Direction Finding Scheme Of Outdoor Security Small Intelligent Sound Sensing Sensor Node

With the development of science and technology,there is no doubt that the time of digital network has already come.In this era,because of the trend of intelligent home and modern management and the smart community,the emergence of intelligent security is becoming inevitable.This paper,based on the outdoor far-field environment,the smart sensor network is used to locate the sound source localization and the direction-finding system composed of the small microphone array is used as the intelligent sensing node.The intelligent acoustic sensor network,based on distributed structure,has superior performance,such as low cost,simple and flexible deployment,high precision and so on.It can be used in many fields,including outdoor monitoring.In this paper,the direction-finding system consists of three parts,namely sensing,processing and communication.This system can be used to achieve the direction of the sound source location by signal processing.The shield of the intelligent sensor nodes are made of metal materials,which can protect the internal circuits to work for a long time without people around,no matter it is in hard environments or bad weather.For environment monitoring,it is not necessary to process the signal at the same time in the intelligent acoustic sensor network,so we use one method called intermittent-processing.By the limit of the small size of the system structure and the computing performance of the processor,the data processing capacity of the node can't be too large.It is necessary to adapt the time for fast calculation.This paper we use the combination of voice activity detection algorithm and PHATGCC.The collected data is processed with VAD to detect the active signal segment and then the PHATGCC algorithm is used to estimate the direction of sound source.Then,the processing result is sent to the backstage.The backstage uses positioning algorithm to achieve the localization of the sound source.This method of single-node-direction and multi-node-location reduces the processing capacity and the communication bandwidth on the node.In fact,when a single node,whose property is limited due to the small structure and the encapsulation shell,is used to find the direction,the result of source-direction-finding will have a certain error.Based on the problems above,a variety of experiments have been implemented and the results are analyzed to figure out the origin of errors.In order to improve the accuracy of small smart sensor nodes,a method of compensation for errors is proposed,which is a foreshadow for the localization of intelligent sensor networks in practical application.