摘要:
试验了一种能够在含水的岩层、土壤甚至海水中建立起无线通信的系统和方法。该系统的关键部件,高灵敏接收前端和接收机使用的是商品级高温超导量子干涉仪(high critical temperature superconducting quantum interference device, HTc SQUID)磁强计和商用高速、高精度数据采集处理系统。目前在从30 Hz到100 kHz频段内,商品级HTcSQUID磁强计可以提供优于100 fT/Hz1/2的内秉磁场噪声谱密度,同时商用数据采集处理系统可通过软件实现对传输信息的调制、采集、解调和分析。利用低频电磁波在导电介质中有较大穿透深度以及HTcSQUID磁强计低频磁场灵敏度高、体积小的特点,对于一种能在地下(岩石和土壤)和水下(海水)环境中使用的可移动式低频无线电通讯系统实现的可行性,进行了初步讨论。使用面积等于1 m2的方形线圈作为测试信号的辐射体(发射天线),将SQUID磁强计的传感器封闭在一个能对超低频测试信号提供较大衰减的电磁屏蔽体中,成功地接收到了发射线圈辐射的99 Hz调幅信号。因此证明,采用HTcSQUID技术,可以在地面与数百米深的地下建立起有实用价值的无线电通信。
Abstract:
System and methods for wireless communication that could go through hydrous rocks, seawater, and even soil are investigated. The key components of the system are the high sensitive receivers of commercial HighTcSQUID and high-speed signal acquisition and processing systems. Within the frequency band of 30 Hz to 100 kHZ, the intrinsic noise spectral density of commercial HTcSQUID could be as good as 100 fT/Hz1/2, so that with commercial software, signals could be accurately modulated, collected,demodulated and processed. In the low frequency end, with the features of long penetration depth of electromagnetic wave and high sensitive, small size of HTcSQUID magnetometer, the feasibility of the implementation of portable low-frequency wireless communication system which could be used both under ground and water is discussed preliminarily. Using a 1 m2 square coil as test signal transmitting antenna, with the HTcSQUID magnetometer receiving sensor placed in an electromagnetic shielding cavity which could provide considerable electromagnetic attenuation, the 99 Hz AM signal emitted by the transmitting antenna is successfully collected. The result proves that with the technology of HTcSQUID, practical wireless communications can be realized between the earth’s surface and a depth of hundreds of meters underground.
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