In this paper, development of through-the-earth communication technologies is summarized, as well as the operating principles and performances. The propagation loss, frequency band and power efficiency are also analyz...In this paper, development of through-the-earth communication technologies is summarized, as well as the operating principles and performances. The propagation loss, frequency band and power efficiency are also analyzed. We can know that among these technologies, the antenna induction method is more popular, but the communication system with ground electrodes is more promising due to its high energy efficiency. The communication with elastic wave （seismic） is not suitable for emergency communication when the accidents of rock burst or land slide occur.展开更多
In low-frequency elastic wave through-the-earth communication system,because of multipath transmission caused by characteristics of the layered earth,the time domain equalizer is different from other wireless communic...In low-frequency elastic wave through-the-earth communication system,because of multipath transmission caused by characteristics of the layered earth,the time domain equalizer is different from other wireless communication systems.A modified LMS algorithm of variable step size is proposed based on improvement of traditional LMS.On the base of principle and simulation analysis,the improved Least Mean Square(LMS)algorithm is analyzed and the performances are compared between the improved LMS algorithm and traditional LMS algorithm.In the improved algorithm,the contradiction between convergence speed and the steady-state error is considered at the same time.Therefore,the improved algorithm has good convergence properties and channel-tracking performance.展开更多
基于FEKO7.0建立了矿井无线透地通信磁场模型,设计了3种体积不同、匝数不同但输入电阻相同的铁氧体磁性天线,研究了该模型在地面上的磁场分布情况,频率采用甚低频15 k Hz。结果表明:这3种铁氧体模型在地面上产生了3种不同数量级的磁场强...基于FEKO7.0建立了矿井无线透地通信磁场模型,设计了3种体积不同、匝数不同但输入电阻相同的铁氧体磁性天线,研究了该模型在地面上的磁场分布情况,频率采用甚低频15 k Hz。结果表明:这3种铁氧体模型在地面上产生了3种不同数量级的磁场强度,并采用竖直和水平两种安装方式,其量值都在电磁传感器可以检测到的范围内。研究发现,地面产生磁场强度的大小与铁氧体天线的体积和放置形式有关,水平放置比竖直放置产生了较大的磁场强度。因而,利用磁场代替调制电磁波作为矿井无线透地通信的传输媒介是可行的。展开更多
基金Foundation item： National Nature Science Foundation of China （No. 61272432）
文摘In this paper, development of through-the-earth communication technologies is summarized, as well as the operating principles and performances. The propagation loss, frequency band and power efficiency are also analyzed. We can know that among these technologies, the antenna induction method is more popular, but the communication system with ground electrodes is more promising due to its high energy efficiency. The communication with elastic wave （seismic） is not suitable for emergency communication when the accidents of rock burst or land slide occur.
基金supported by the National Natural Science Foundation of China(No.61071016)
文摘In low-frequency elastic wave through-the-earth communication system,because of multipath transmission caused by characteristics of the layered earth,the time domain equalizer is different from other wireless communication systems.A modified LMS algorithm of variable step size is proposed based on improvement of traditional LMS.On the base of principle and simulation analysis,the improved Least Mean Square(LMS)algorithm is analyzed and the performances are compared between the improved LMS algorithm and traditional LMS algorithm.In the improved algorithm,the contradiction between convergence speed and the steady-state error is considered at the same time.Therefore,the improved algorithm has good convergence properties and channel-tracking performance.
文摘基于FEKO7.0建立了矿井无线透地通信磁场模型,设计了3种体积不同、匝数不同但输入电阻相同的铁氧体磁性天线,研究了该模型在地面上的磁场分布情况,频率采用甚低频15 k Hz。结果表明:这3种铁氧体模型在地面上产生了3种不同数量级的磁场强度,并采用竖直和水平两种安装方式,其量值都在电磁传感器可以检测到的范围内。研究发现,地面产生磁场强度的大小与铁氧体天线的体积和放置形式有关,水平放置比竖直放置产生了较大的磁场强度。因而,利用磁场代替调制电磁波作为矿井无线透地通信的传输媒介是可行的。
