A new whistler direction finder

Okada, T.; Iwai, Akira; Hayakawa, Masashi

doi:10.1016/0021-9169(81)90140-9

Cited by 33 publications

(13 citation statements)

References 10 publications

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“…MEASUREMENT AT YAMAOKA The direction finding system in the present paper is based on the measurement of two horizontal magnetic field components and one vertical electric component of VLF waves. Its principle is essentially the same as that of the four-parameter method originally proposed by Crary [1961] and later adopted by ' Tanaka [1972], Cousins [1972], Tsuruda and Hayashi [1975], and Okada et al [1977Okada et al [ , 1981. It is extremely important from the geophysica!…”

Section: The Automatic Direction Findingmentioning

confidence: 98%

“…Thus magnetic tapes were wastefully used during the periods when whistlers were not recorded, andS furthermore we were obliged to make an elaborate aural monitoring even during those periods. Hence the available number of direction finding results by those authors is extremely small, so that the wave normal directions only for several intense whistlers during a few hours on a specific day have actually been presented in the works by Tsuruda and Hayashi [1975] and Okada et al [1981]. However, in their later paper, Okada et al [1981] have attempted to compensate for this defect by incorporating an auxiliary real time whistler analyzer with the direction finder, enabling them to have good timing for the start and stop of the direction finding and, in turn, resulting in less use of magnetic tapes and less analyzing effort.…”

Section: The Automatic Direction Findingmentioning

confidence: 99%

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Ducted propagation of daytime whistlers at low latitudes as deduced from ground‐based direction findings

Ohta¹,

Hayakawa²,

Tanaka³

1984

J. Geophys. Res.

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The purpose of the present paper is to promote our understanding of the propagation characteristics of daytime whistlers at low latitudes on the basis of the data obtained by a newly developed automatic direction finding measurement at Yamaoka (geomagnetic latitude 25°N) and the synoptic routine data from the multistation network of Kagoshima (20°), Sakushima (24°), and Moshiri (34°). Two events of daytime whistlers with extremely enhanced occurrences are found on January 16 and 15, 1982, and they are examined in detail. It is found that the ionospheric exit points determined by the direction finder at Yamaoka remain very stable for less than 2 hours, so that the diameter of their distribution is less than 60 km. This experimental fact is likely to be strongly indicative of ducted propagation. An intercomparison of the whistler spectra at the four stations has been made for these events. Then it is shown that the whistlers that emerged near Yamaoka and Sakushima tend to propagate in the earth‐ionosphere waveguide toward higher latitudes, being observed at Moshiri with their frequency component cut off at frequencies below the tweek cutoff frequency, while heavily attenuated corresponding whistlers are simultaneous at Kagoshima. This phenomenon is again satisfactorily explained in terms of ducted propagation.

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Section: The Automatic Direction Findingmentioning

confidence: 98%

Section: The Automatic Direction Findingmentioning

confidence: 99%

Ducted propagation of daytime whistlers at low latitudes as deduced from ground‐based direction findings

Ohta¹,

Hayakawa²,

Tanaka³

1984

J. Geophys. Res.

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“…In order to measure the polarization and arrival direction of VLF waves, Okada et al [19,20] developed a spaced direction-finding technique. In this technique the VLF signals are received by two orthogonal loops; each loop with two turns having an area 144 m 2 .…”

Section: Analyses and Resultsmentioning

confidence: 99%

Daytime hiss-triggered chorus emissions observed at low latitude ground station Srinagar, India

et al. 2010

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The first observation of hiss-triggered discrete chorus riser emissions recorded during daytime at our newly setup low latitude ground station Srinagar (geomag. lat., 24 o 10¢ N; L = 1.28), India on March 30, 2009 are reported. From the spectral analysis of these emissions, it is found that the chorus is hiss-triggered and each chorus element has the tendency to originate from the hiss band. A possible generation mechanism of these hisstriggered chorus riser emissions is proposed.

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“…Direction-finding methods such as the goniometer method [2] and the electromagnetic field analysis method [3,4] used for direction estimation of whistler assume a single plane wave and correspond to the model with K = 1 in Eq. (1), where the noise w is neglected.…”

Section: Data Model With Direct Wave Onlymentioning

confidence: 99%

ELF/VLF direction‐finding taking account of earth‐ionosphere waveguide effect

Sakai

Shimakura

2002

Electron. Comm. Jpn. Pt. I

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SUMMARYEstimation of the transmission point in the ionosphere for ELF/VLF waves arriving at the ground after propagation in the magnetosphere is performed by MUSIC, an estimation method having high resolution. This paper not only constructs an estimation method based on the observation data model common to various direction-finding methods, but also proposes a method of estimating the direction and polarization of the direct wave by using a model that expresses the propagation effects between the ground and the ionosphere in terms of superposition of multiply reflected waves. In the simulation assuming observation of three electromagnetic field components on the ground, the results of estimation by both methods are compared. It is confirmed that the estimated values are superior to those obtained by the conventional methods if more than 10 reflections are taken into account for estimation of a transmission point that is far away with a large angle of incidence at the observation point. Even when the wave is transmitted through the spread-out region in the lower ionosphere, the direction of the center of the transmission region can be estimated by MUSIC taking account of multiply reflected waves.

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A new whistler direction finder

Cited by 33 publications

References 10 publications

Ducted propagation of daytime whistlers at low latitudes as deduced from ground‐based direction findings

Ducted propagation of daytime whistlers at low latitudes as deduced from ground‐based direction findings

Daytime hiss-triggered chorus emissions observed at low latitude ground station Srinagar, India

ELF/VLF direction‐finding taking account of earth‐ionosphere waveguide effect

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