矿井井筒中电磁波传播特性研究与无线通信试验

为获得矿山井筒环境中的无线信道特性,在矿山井筒中开展了2.4 GHz典型电磁波频段在定向天线点对点通信形式下的窄带与宽带测量试验,呈现了路径损耗、时延扩展等关键信道参数及其分布规律并与地下巷道信道进行了对比讨论。结果表明:路径损耗系数小于自由空间,表现出波导效应;RMS时延扩展符合对数正态分布,其均值小于巷道中的测量结果;随罐笼深度的增加,RMS时延扩展先增加后减小;90%相干度带宽在绝大多数情况下小于12 MHz,可传输视频、语音、数据;综合来看井筒环境中信道条件良好。在信道认知的基础上设计了基于WLAN的罐笼无线视频监控系统,该系统在现场运行一年多效果良好。这些研究对井筒通信与监测系统设计提供了重要依据和参考。

Radio channel characterization study and wireless communication trial in mine shaft

In order to obtain the radio channel characterizations in mine shaft environment,the narrowband and wideband channel measurements at 2. 4 GHz were carried out in a real mine shaft in the condition of point-to-point communication with directional antennas. Important parameters such as path loss and delay spread were presented and compared with that in underground roadways. The results show that the path loss exponent is smaller than that in free space,showing a waveguide effect. RMS delay spread was found to follow the lognormal distribution. Its mean value was found smaller than that in underground roadways. It was also found that the RMS delay spread increases then decreases with the increase of Tx-Rx distance. The 90% coherence bandwidth is mostly less than 12 MHz,meaning a transmission capacity of data,voice and video. In general,the shaft channel condition is sound. A video surveillance system based on the WLAN was designed. The field test was conducted with a good performance for over a year. The study provides important parameters and reference for designing mine shaft communication and monitoring systems.