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Very low frequency

About: Very low frequency is a research topic. Over the lifetime, 1540 publications have been published within this topic receiving 24233 citations. The topic is also known as: VLF.


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Journal ArticleDOI
TL;DR: In this paper, a VLF receiver was used to detect broadband electrostatic emissions from the satellite OV3-3 (1966-70A) at frequencies between 400 Hz and 14.5 kHz at altitudes between 2500 and 4500 km.
Abstract: : Broadband electrostatic emissions are detected by a VLF receiver aboard the satellite OV3-3 (1966-70A). Enhancements of the electric-field intensity in ten bandpass channels at frequencies between 400 Hz and 14.5 kHz are observed when the spacecraft passes over the south polar region at altitudes between 2500 and 4500 km (satellite apogee). The power spectral density of these emissions decreases approximately as the inverse fourth power of the observed frequency. The most interesting feature of these emissions is the range of invariant-magnetic-latitudes (INVL) over which they are observed. The low-latitude limit at which they are detected is typically 72 to 76 degrees INVL in local morning and 68 degrees INVL near midnight. This dependence suggests that these emissions occur on magnetic-field lines along which the polar wind flows. During geomagnetically active periods, electrostatic waves with a high-frequency cutoff between 1.3 and 3.9 kHz are also observed in this altitude range. These emissions occur at latitudes below the low-latitude limit of the polar-electrostatic waves and above the latitude of the plasmapause. (Author)

6 citations

ReportDOI
01 Mar 1992
TL;DR: In this article, the authors present the results of a statistical study of a year of data obtained as part of the STAR Laboratory's global survey of ELF/VLF radio noise (frequencies in the range 10 Hz to 32 kHz).
Abstract: : In this report we present the results of a statistical study of a year of data obtained as part of the STAR Laboratory's global survey of ELF/VLF radio noise (frequencies in the range 10 Hz to 32 kHz). The data included in the study were obtained from seven measurement instruments (radiometers) located at both high and low latitudes. Average amplitude and voltage deviation (d) statistics from each of the six stations were first divided into four three- month seasons and then averaged at every measurement frequency to give two separate sets of long-term averages. Long-term averages show characteristic trends in the measurements due to the manner in which noise propagates in the earth-ionosphere waveguide. The average amplitudes of the measurements decrease with frequency, reaching a minimum around 1 kHz, and rise again towards 10 kHz. The voltage deviation amplitudes generally rise with frequency except for a depression of values around 1 kHz.

6 citations

Patent
04 Sep 2009
TL;DR: In this article, a signal processor (104) separates a signal space associated with the at least one signal in the one radio frequency band and a background space associated to interference and noise in the other radio band.
Abstract: A receiver receives at least one radio frequency band. A signal processor (104) separates a signal space associated with the at least one signal in the at least one radio frequency band and a background space associated with interference and noise in the at least one radio frequency band. For a simulation, a memory (106) stores the environment data of the at least one radio system based on the background space under control of the signal processor (104).

6 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202320
202232
202156
202048
201942
201852