【摘要】 极低频电磁方法是近几年来在我国首先发展起来的地球物理新方法,可以应用于资源、能源及深部工程地质勘查中,其特色之处是在高阻区建立近南北方向和近东西方向两个长达上百公里的人工固定发射源,发射大功率电磁信号。2015年11月底发射台建设完成后,首要任务是检测远处记录的极低频电磁信号的强度和有效性,为此,我们在距发射源960 km的华北油田任丘盆地开展了首次信号测试试验:用高精度采集站接收发射信号,然后进行分段频谱分析,获得接收信号的频率谱,通过分析接收信号频谱的强度与信噪比评价发射信号的质量和有效性。在试验正式开始之前,先用10个均匀分布的频率确定最佳发射时间长度,其他频率的发射时间长度通过内插获得,以节省发射时间。通过试验,在离发射源960 km处成功检测到了电磁场有效信号。当东西方向天线发射频率高于0. 353 78 Hz和南北方向天线发射频率高于1. 4151 Hz时,与发射源方向一致的电磁场分量的信噪比都大于3,认为信号可靠可测。这次试验初步认定建成的发射台能够发射有效信号,可允许在全国各地进一步实施各种检测和联调试验研究。更多还原

【Abstract】 The wireless electromagnetic method is a new geophysical method developed in recent years. It can be applied to resources,energy and deep engineering geological exploration. Its characteristic is that two directions long bipole near-south-north and near-east-west are established in high-resistance areas. With hundreds of kilometers of emission sources,high-power electromagnetic signals can cover the whole country. After the project of transmitter station being completed at the end of November 2015,the first signal test was carried out in the Renqiu Basin of the North China Oilfield,which is 960 kilometers away from the transmitter source. The signal was collected by high-precision acquisition system,and then the frequency spectrum was obtained by performing segmentation spectrum transformation. At last,the transmitted signal was evaluated through analyzing the signal-tonoise ratio and spectrum amplitude. Before the test,the optimal transmit duration was determined by a few uniformly distributed frequencies to save time. Other frequencies transmit duration can be obtained by interpolation.Through experiments,the electromagnetic field signal was successfully detected. When the frequency is greater than0. 353 78 Hz with east-west bipole source,and the frequency is higher than 1. 4151 Hz with north-south bipole,source,the signal-noise-ratio is greater than 3 and considered being measurable. The test showed that the transmitter station can transmit effective signals,and other tests and joint test studies could be carry out in the whole country.更多还原