Design And Implementation Of Voice Communication Terminal System Based On Zigbee

The coal mine safety is always the focus of the public. The research of wireless voice communications technology for coal mine provides a good solution for coal mine safety management. Because of the complexity of environment in coal mines, terminal equipments of coal mine must have the characteristics, such as low power consumption, low cost, high reliability, strong restoring ability and so on. ZigBee technology just has the above characteristics, it is a new type of wireless sensor network technology. Traditionally, the data of ZigBee transmitting is non real-time data. However, Wireless voice communication is real-time data transmission, so it is necessary to compress the voice data in order to reduce the amount of data transmission. ADPCM compression algorithm have many prominent characteristics, such as high compression rate, good speech quality and low cost. So it is suitable for using in the ZigBee wireless communication system whose bandwidth is limited.This paper compares several wireless transmission technologies and speech coding technologies. On basis of these, this paper focuses on ZigBee wireless communication technology and ADPCM voice compression coding algorithm and designs to implement a system of voice communication terminal based on ZigBee technology. The system implements the real-time transmission of voice data using ZigBee technology, and the user can switch the operating mode flexibly on the Qtopia graphical interface. At last, the system completes the half-duplex voice communication between devices.The main content of the article is as follows.(1) Discussing and analyzing of the purpose and significance of the thesis, summing up the technology development and research of wireless voice communications for coal mine, and overviewing of the main research work.(2) Making some analysis and comparison of several commonly used radio frequency technology and voice encoding algorithm, this essay focuses on ZigBee wireless communication technology which is on the basis of IEEE802.15.4and ADPCM voice compression coding algorithm. Combined with the particularity of the mine devices, it designs the process of implementation and structure of voice communication terminal system based on ZigBee; Researching and analyzing Qtopia graphical interface, at last giving the whole design schemes of system.(3) Researching and implementing the hardware design of system, including the analysis and selection of the main chip, setting up the hardware platform, circuit designing, making and commissioning of all of functional modules. The software part, studying and analyzing of the operation process of the device under the Linux platform; designing and implementing procedures of the ADPCM algorithm; deeply studying the ZigBee protocol stack, network building processes, and wireless data transmission and so on; completing the development of application program on these basis and the wireless transmission of voice data; completing the design of Qtopia graphical user interface.(4) After testing, the voice terminal system completes the task of voice signal acquiring and preprocessing, ADPCM coding, wireless data sending and wireless data receiving, ADPCM decoding, voice signal playing. The loss rate of data packet in Wireless transmission is low, delay is short, therefore the voice quality(MOS) is high.