scholarly journals A detailed investigation of low latitude tweek atmospherics observed by the WHU ELF/VLF receiver: I. Automatic detection and analysis method

2020 ◽  
Vol 4 (2) ◽  
pp. 120-130 ◽  
Author(s):  
RuoXian Zhou ◽  
◽  
XuDong Gu ◽  
KeXin Yang ◽  
GuangSheng Li ◽  
...  
Keyword(s):  
Automatic Detection ◽  
Analysis Method ◽  
Low Latitude ◽  
Tweek Atmospherics

Automatic detection of lunar craters based on DEM data with the terrain analysis method

2018 ◽  
Vol 160 ◽  
pp. 1-11 ◽  
Author(s):  
Yi Zhou ◽  
Hao Zhao ◽  
Min Chen ◽  
Jie Tu ◽  
Long Yan
Keyword(s):  
Automatic Detection ◽  
Terrain Analysis ◽  
Analysis Method ◽  
Lunar Craters

scholarly journals Higher harmonic tweek sferics observed at low latitude: estimation of VLF reflection heights and tweek propagation distance

2008 ◽  
Vol 26 (6) ◽  
pp. 1451-1459 ◽  
Author(s):  
S. Kumar ◽  
A. Kishore ◽  
V. Ramachandran
Keyword(s):  
Attenuation Factor ◽  
Lower Ionosphere ◽  
Propagation Distance ◽  
Transverse Magnetic ◽  
Pacific Region ◽  
Low Latitude ◽  
Transverse Magnetic Mode ◽  
Magnetic Mode ◽  
Tweek Atmospherics ◽  
Higher Harmonic

Abstract. Lightning generated signals recorded at a low-latitude station, Suva (18.2° S, 178.3° E) Fiji, in the South Pacific region, during September 2003–July 2004, are used to study the propagation features and the reflection heights of tweek atmospherics in the waveguide formed by the Earth's surface and the lower ionosphere. Tweeks are observed only during the local night and the maximum harmonic (n) recorded is six. The occurrence of tweeks with higher n progressively decreases as n increases. The dispersed part of tweeks decreases as n increases. The attenuation factor has been calculated for tweeks with n=1–3. The ionospheric reflection heights obtained assuming the transverse magnetic mode of propagation for tweek signals vary from 83–92 km. A higher harmonic of the same tweek is reflected from about 2.0 km higher than the lower harmonic. For 90% of tweeks, propagation distances are estimated to be between 1000–5000 km. Tweeks with lower n propagate longer distances than the tweeks with higher n.

scholarly journals Automatic detection of atmospherics and tweek atmospherics in radio spectrograms based on a deep learning approach

2021 ◽  
Author(s):  
Viera Maslej‐Krešňáková ◽  
Adrián Kundrát ◽  
Šimon Mackovjak ◽  
Peter Butka ◽  
Samuel Jaščur ◽  
...  
Keyword(s):  
Deep Learning ◽  
Automatic Detection ◽  
Learning Approach ◽  
Tweek Atmospherics

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

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