Design Of Mining Location-Based Services Terminal With Wi-Fi Technology

In recent years, with the continuous development of data acquisition technology and communication technique, the coverage area and automation level of "the six systems" of coal mining enterprises in China have made great progress. Underground wireless communications technology, as the key of the management and communication technologies of the coal mine six systems, has been attacting a lot of attention. By comprehensive comparison of wireless communication technology which have appeared in the production process of coal mining, based on the far Wi-Fi technology transmission distance, the high speed of data transmission and the convenient networking, the feasibility and implementation of the Wi-Fi technology application in the mining safety production was introduced in this design.Wi-Fi-based Location-Based Services (LBS) terminal, combining Wi-Fi wireless com-munication technology with the LBS mobile location services technology which is popular recently, aim at low power comsumption and the the requirements of intrinsically safe for un-derground Wi-Fi wireless communication terminal equipment with the high-performance, low-power microprocessor STM32F107VC. With the location information in the positioning unit which is constituted by four AP access points, LBS terminal was required to achieve the function of real-time monitoring and uploading the gas concentration monitoring data in the position which terminal current located, and the SIP voice conversation function.The main content Hardware design part of Wi-Fi-based Location-Based Services (LBS) terminal includes:the chip selection of microprocessors、Wi-Fi module and audio processor STM32F107VC minimum system design, WM-G-MR09-REF2Wi-Fi module circuit and antenna design and circuit connection, the electric connection of MIC、8-ohm speaker and PCM3500audio codec and power amplifier circuit design, keyboard and LCD display mod-ule design. In addition, based on the design of the hardware main requirements in accordance with the National intrinsically safe electrical equipment, intrinsically safe design for the printed circuit board is optimized.The main content of software design part of Wi-Fi-based Location-Based Services (LBS) terminal includes:underground tunnel Wi-Fi positioning mechanism design, determination and correction method of the path loss coefficient and the shadowing factor in the Wi-Fi posi-tioning mechanism which is given in this paper, the μC/OS-11system porting on STM32F107VC. the Wi-Fi driver with SP1interface on μC/OS-11system, SIP-based VoIP voice communication function design.The experiment of the Wi-Fi-based LBS terminal focused on μC/OS-11system transplan-tation on STM32F107VC which part of the system have achieved relative success and the simulation of the Wi-Fi positioning mechanism which have accomplished basically. However, due to the limitations of the experimental conditions, the underground simulation environment was not established, and the positioning results in the laboratory shows that:the positioning accuracy is relative high when the test terminal is located at the interior center position, while positioning accuracy is unsatisfactory when the terminal is located on the edge of the cover-age area of the positioning unit.All in all, the hardware part design of the Wi-Fi-based Location-Based Services terminal basically completed, but two aspects of software design, the classification, compression and transmission of data and the low-power management program, still needs further improved. Testing of the terminal, it is necessary to establish the experimental environment simulated the long straight underground roadway. The Wi-Fi positioning, voice communication function need further testing, and the results of data transmission performance should be given com-bined with the simulation server and the ground monitoring client by PC.