Observations of CD-seismic Electromagnetic Phenomena in VHF Band

在我们的调查中，对地震电磁现象进行了观测，以解决以下问题。1.是否会出现与情商相关的电磁现象？2.均衡器是否使电离层反射调频广播波？为了实现我们的观测，我们构建了甚高频观测系统。我们的观测系统的特点如下。-调频广播波段观测：该波段几乎不受人为或城市噪声的影响。-双频观测：为了区分地震宽带现象和调频广播波，我们开发了一种新的双频观测方法，即在两个不同的频率上进行观测-数字调频调谐器观测：该调谐器具有高频率选择性和稳定性，可以实现定量观测。(2)观察其中回答。地震电磁现象的观测我们可以观测到地震现象。参见Geiyo EQ (2001), Ibaraki-ken-oki EQ (2002), niigata -ken- chuetsu EQ（2004）。在这些均衡器中，观察到宽带电磁波。发现这些观测到的电磁波是由观测点附近陆地的地震摆动产生的。此外，在VHF波段探测到的其他电磁现象在地震发生时消失。从Geiyo EQ的前一天开始，观察到大约2 dB的振幅波动，然后在EQ 2发生时波动消失。远程调频广播传播观测在茨城县观测站观测到仙台77.1 MHz调频广播波。通过观测发现，调频广播波在对流层管道或地圈上传播。观测结果表明，EQ对电离层反射调频广播波的影响不大。(3)观测系统的改进。特别是在高电场强度的情况下，为了减小互调失真，需要插入BPF。少

1)Observation systemIn our investigation, the observation of seismic electromagnetic phenomena have been conducted to solve these following subjects. 1.Does electromagnetic phenomena associated with EQ occur? 2.Does the EQ make the ionospheric layer reflect the FM broadcasting waves? To realize our observation, we have constructed the VHF band observation systems. The feature of our observation system is as followings.- Observation in FM broadcasting band : This band is hardly influenced by artificial or urban noises.- Dual Frequency Observation : To distinguish the seismic broadband phenomena from FM broadcasting waves, we have developed a novel dual frequency observation method in which the observation is made attwo different frequencies- Observation using digital FM tuner : This tuner has high frequency selectivity and stability, and thequantitative observation can be realized.(2)Observation results1.Observation of seismic electromagnetic phenomenaWe could observe the seismic phenom … More ena in Geiyo EQ (2001), Ibaraki-ken-oki EQ (2002), and Niigata-kenChuetsu EQ (2004). In these EQ, the broadband electromagnetic waves were observed. And it is found that these observed electromagnetic waves are generated from the seismic swing of the land near the observation site. Moreover, the other EM phenomenon detected in VHF band disappeared at the time of earthquake. Amplitude fluctuations of about 2 dB were observed since one day before the Geiyo EQ, then, the fluctuations disappeared at the occurrence of EQ.2.Observation of long-distance FM broadcasting propagationThe 77.1 MHz FM broadcasting wave from Sendai has been observed in Ibaraki observation site. From this observation, it is found that the FM broadcasting wave propagates in the tropospheric duct or on the geosphere. Our observation results show that the EQ hardly influence the ionospheric layer to reflect the FM broadcasting waves at the occurrence of EQ.(3)Improvement of observation system.Especially in the high electric field strength, the BPF should be inserted to reduce the intermodulation distortion. Less