Research On Bird Sound Acquisition System With Star Network Structure

Birds are significant creatures in nature,while birdsong is a biological trait of birds as an approach to identifying bird species,which is of great significance in biodiversity monitoring and ecological environment preservation.The existing bird sound acquisition methods are generally recorded and stored by placing the recording devices in the related field area in accordance with the set program,then the staff retrieve the memory card before manually data process and analysis on a regular basis.In this way,the sound data of the target area continuously could be recorded for up to two or three months with no need for manual duty,yet it is of poor real-time performance,while there are many sound signals are stored without bird sound,which consumes storage resources.In order to enhance the timeliness,the staff can record the bird sound on the spot,but due to limited recording area,the amount of recorded bird sound data is small,while the person in the field may affect the bird activity.Besides,it is viable to capture the target birds from the wild,and collect their sound in the laboratory.Despite the superior sound quality,it seriously jeopardizes the normal life of the birds.With the advancement of wireless communication technology,some remote acquisition systems based on wireless network have emerged to realize real-time data acquisition without manual intervention,which brings great convenience to bird sound collection.Nevertheless,there are still some problems in the current remote collection system,such as the constraint in wireless network,data sharing and equipment production cost,thus making it impossible to carry out deployment on a large scale.With the purpose to collect bird sounds remotely and wirelessly,this paper studies and designs a bird sounds acquisition system with star topology structure.First,the remote bird sound acquisition system scheme is designed,including signal acquisition terminal,wireless gateway,and Ali cloud server.To facilitate large-scale deployment,the low-cost single-chip microcomputer is taken as the main processing chip,with NXP RT1052 for the terminal,STM32F407ZGT6 to transmit data and commands via LoRa between the terminal and wireless gateway,as well as the wireless gateway communications with Ali cloud server via 4G network.Second,the sound signal preprocessing algorithm of bird sound acquisition terminal is designed for noise reduction,segmentation,screening and compression.Based on the WebRTC noise reduction algorithm,an improved method on the basis of the maximum posterior estimator is proposed to effectively suppress background noise;A method of analyzing the nonlinear frequency domain is proposed by employing the segmentation algorithm based on prior probability;The resonance peak estimation approach according to linear prediction is applied to obtain the characteristic information of each subchip in the sound segment.By classifying and statistics,it can judge whether there is a bird sound signal in the sound section,and further screen the fragments containing the bird sound;then compress the bird sound segment into MP3 to cut down the data quantity.Third,the network mode of star topology is adopted,in which the gateway conducts time-sharing roll polling and procure the audio files with sound acquisition terminal for each bird through LoRa module,after that,upload these bird sound files to Ali cloud server via 4G wireless network to complete the process of data on the cloud,and then extend species identification and other application services.This design system realizes the remote bird sound data collection,which can offer on-site sound data for bird sound identification as well as animal acoustics research and ecological environment supervision.