Design And Implementation Of Embedded VoIP Terminal Based On Speex

There are many troubles in underground work,such as harsh environments,complex process,wiring difficulties,security risks.So it need higher requirements in real-time communication,security and other respects.Because of technique and other limitations,many communication technology can't be effectively applied to the coal industy.Therefore,it is very valuable to design a more efficient and more secure communication system.Design a embedded VoIP voice terminal based on WiFi technology to meet the challenges.At the network level,use low cost,low power,high density WiFi AP as a basestation,to form a cellular network infrastructure.This focuses on the design and implementation of VoIP voice terminal based on Speex.On the hardware side,considering the low-cost,low-power design requirements,codec chip W681310 is selected,which complete conversion analog voice signals and PCM signal,and the A-Law and u-Law compression decoding expansion;the Shanghai Qingke company's WiFi module EMW3162 is selected as the master chip,this module comes with a low-power and high-performance microcontroller STM32F205RG,and WiFi front,supports the secondary development;as for the power part,considering the characteristics of lithium batteries charging,SE9017 is selected as the charge management chip to ensure the safe and efficient lithium battery charging;ME2802 is selected as the power monitoring chip to complete real-time detection of battery power.In terms of software,embedded operating system FreeRTOS is ported first;secondly,complete the speech codec-W681310 driver design,and the equipment can be properly PCM codec;thirdly,port the software Speex codec,the codec is capable of higher bandwidth PCM data compression processing,effectively reduce bandwidth and improve network capacity;fourthly,implement the SIP UE entuty,supporting the external network phone calls.Fianlly,use serial assistant and Wireshark to test the communication performance of voice terminals,the test results show that the terminal can achieve communications between tbe terminals,as well as calls between the terminal and the external network phone,and call quality is good,and achieve the desired design goals.