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首页> 外文期刊>Radio Science >Interferometric direction finding of over-horizon VHF transmitter signals and natural VHF radio emissions possibly associated with earthquakes
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Interferometric direction finding of over-horizon VHF transmitter signals and natural VHF radio emissions possibly associated with earthquakes

机译：可能与地震有关的超视距VHF发射机信号和自然VHF无线电辐射的干涉仪测向

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摘要

The over-horizon (out-of-sight) VHF transmitter signals are found to be received before an earthquake, and also natural VHF noises are known to be detected prior to an earthquake. In order to have a better understanding of these over-horizon VHF signals and noises, an interferometric direction-finding system has been, for the first time, introduced, and some preliminary observational results have been presented here. With FM Sendai as a target VHF transmitter (at 77.1 MHz), we have carried out the observation at Chofu (Tokyo). We can receive occasionally the over-horizon VHF transmission signals in possible association with earthquakes. We have analyzed a few earthquakes since the commencement of our observation, including a large one named the Niigata Chuetsu-oki earthquake. The azimuth distribution by means of the interferometer has enabled us to correlate any burst in the temporal evolution of electric field intensity to a certain earthquake. The over-horizon VHF transmitter signals are always well above the background noise, whose azimuth is found to be relatively close to the direction of Sendai (relatively away from the epicentral direction). Then, the VHF radio noises are always simultaneously detected as an enhancement of background noise, with their azimuths being relatively close to the epicenter of the quake. The mechanisms of seismoatmospheric perturbations as seen from the over-horizon VHF signal, as well as the natural VHF noise, are discussed.
机译：发现超视距（视线外）的VHF发射机信号在地震前已被接收到，并且已知在地震前会检测到自然的VHF噪声。为了更好地了解这些超视距VHF信号和噪声，首次引入了干涉式测向系统，并在此提供了一些初步的观测结果。以FM仙台作为目标VHF发射机（在77.1 MHz下），我们在调布（东京）进行了观测。我们有时会收到可能与地震有关的超水平VHF传输信号。自观测开始以来，我们已经分析了几次地震，其中包括一场名为新泻中越冲木大地震。借助于干涉仪的方位角分布使我们能够将电场强度随时间变化的任何爆发与某种地震联系起来。超地平线的VHF发射机信号总是远高于背景噪声，其方位角相对靠近仙台方向（相对远离震中方向）。然后，总是同时检测VHF无线电噪声作为背景噪声的增强，并且其方位角相对靠近地震震中。从超视距VHF信号以及自然VHF噪声来看，讨论了地震大气扰动的机理。

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  • 来源
    《Radio Science》 |2009年第2期|1-10|共10页
  • 作者

    Y. Yasuda; Y. Ida; T. Goto; M. Hayakawa;

  • 作者单位

    Department of Electronic Engineering and Research Station on Seismo Electromagnetics, University of Electro-Communications, Chofu, Japan.;

    Department of Electronic Engineering and Research Station on Seismo Electromagnetics, University of Electro-Communications, Chofu, Japan.;

    Yokokawa Electric Company, Sagamihara, Japan., Department of Electronic Engineering and Research Station on Seismo Electromagnetics, University of Electro-Communications, Chofu, Japan.;

    Department of Electronic Engineering and Research Station on Seismo Electromagnetics, University of Electro-Communications, Chofu, Japan.;

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  • 正文语种 eng
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  • 关键词

    Azimuth; Radio transmitters; Frequency modulation; Antenna radiation patterns; Earthquakes; Electric fields; Receiving antennas;

    机译：方位角;无线电发射机;频率调制;天线辐射方向图;地震;电场;接收天线;

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