Design And Implementation Of Audio Acquisition System Based On Wireless Sensor Network

Wireless sensor networks (WSN) which combines the technology of sensor, embedded system and wireless communications, have a bright application prospect. At present, WSN has been widely used in a specific area sensing and acquisition of scalar information, such as temperature, humidity, light intensity, pressure, PH and so on. However, with the improvement of monitor demand, such scalar information can not meet the full demand for environmental monitoring for people. There is an urgent need for leading information-rich audio, video, image and other media information into environment monitoring base on sensor network, to achieve fine-grained, accurate information on environmental monitoring. Because of these, Multimedia Wireless Sensor Networks (MWSN) which focus on audio, image and video, become one of the present research hot-spots in recent years.This paper designs and implements an audio collection system based on WSN for monitoring migratory birds at the area of lake and swamp. The system need to work at the wild environment of the lake and marsh area for a long time, collecting and transferring audio data by battery power and wireless communication. More attention is acquired for the problem of data processing, network transport, system lifetime and QoS (Quality of Service). It is significant and challenging for the research and application of MWSN.This system is made up of several audio sensor nodes, which are made up of on a microcontroller, a wireless communication module for IEEE802.15.4 protocol, and a high-gain, low noise amplifier. By the wireless communication routing protocol, several sensor nodes can build up a self-organized and ad-hoc wireless network. All the audio data from every sensor node would be centralized to the sink node after local processing, and transmitted to the management software on user terminal by a cable.In order to weigh the contradictions between a large number of data and the limited bandwidth, we are using G726 compression algorithm to process the data; Because of the poor migration and routing protocol of the tiny OS operating system, we prepared lightweight operating system supporting ten tasks and wireless routing protocol based on assessment by hop; As to noise, we design 3-order Butterworth band-pass filter; as for network life cycle, design a customized software dormancy mechanisms and high capacity rechargeable battery; for RF and analog circuits coexistence interference, we used star-shaped network cabling and separation mechanisms in hardware , as well as to improve the practicality, we through numerous tests to find a reasonable length and diameter of the soft-antenna.