Research On Key Technology For Personnel Position Management System In Coal Mine

The underground environment of coal mine is bad, where has many hidden dangers, so it is required effective management for entered staff and real-time position for underground staff. Up to now personnel position system which sold on China market has many disadvantages, such as high power consumption for identification card, weak anti-shielding quality, weak seal quality for identification card, large discrete maximum identified distance parameter, losing cards occasionally when system distinguishes from many identification cards at the same time, weak anti-interference capability and so on. Taking advantage of wireless electromagnetic wave's transmission performance in enclosed environment under coal mine and advanced RF technique, the thesis is aimed to research key technology for improving personnel position system's performance.This system uses button battery to supply power for identification card. In order to reduce power consumption, author chose low power microcontroller and interval mode to transmit recognition information, that is to say, microcontroller is working in power-down mode during transmission intervening time, so identification card's power consumption is very low. When the transmission interval cycle is 0.4s, average working current is lower than 12μA. Manchester encoding, GFSK modulation, LRC checking are adopted, at the same time author used two alarming ways which are light shinning and communicating low-voltage information to center monitoring host when the battery's voltage is lower than 2.2V. Using outside watchdog, it improves system's anti-interference capability. In order to enhance gain and realize transmission distance larger than 50 meters, author adoptλ/4 printed monopole antenna in 2.4GHz, and the ultrasonic welding enclosure made identification cards sealed completely.Which input voltage is 12VDC and working current is less than 100mA, the card reader adopt rectifier, switch power and DC-DC isolation method. System is working in 3.3VDC and 5VDC, the maximum current limit is 200mA, author used dial-op device to configure card reader's address, wireless receiver protocol and baud rate of RS485. Outside watchdog can realize reset system manually. With using micro-strip patch antenna. Because author took advantage of RAM space for microprocessor, the maximum capacity to identify cards was enhanced to 220. This system adopts RS485 communication mode, CRC checking mode, and realizes interface protection.Through different lab testing method, steps and criterion, author tested this system many times in lab, testing tunnel in CQCCRI, and Datong 1st coal mine of Songzao Coal & Electricity CO., LTD. All testing results showed that various indices meet designed performance requirements.