Pulsation phenomena observed in long-duration vlf whistler-mode signals.
Whistler-mode signals from station NAA (14.7 and 17.8 kHz), Cutler, Maine, show periodic fluctuations (?pulsations') in amplitude and bandwidth. The data were recorded at Eights station, Antarctica, during unmodulated (?key-down') transmissions from NAA lasting up to 2 min. In three of fou...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19720029864 2023-05-15T13:53:59+02:00 Pulsation phenomena observed in long-duration vlf whistler-mode signals. Bell, T. F. Helliwell, R. A. Unclassified, Unlimited, Publicly available Dec 1, 1971 http://ntrs.nasa.gov/search.jsp?R=19720029864 unknown http://ntrs.nasa.gov/search.jsp?R=19720029864 Accession ID: 72A13530 Copyright Other Sources 07 Journal of Geophysical Research; 76; Dec. 1 1971 ftnasantrs 2012-02-15T10:57:03Z Whistler-mode signals from station NAA (14.7 and 17.8 kHz), Cutler, Maine, show periodic fluctuations (?pulsations') in amplitude and bandwidth. The data were recorded at Eights station, Antarctica, during unmodulated (?key-down') transmissions from NAA lasting up to 2 min. In three of four instances, the pulsations consist of a series of moderate enhancements of the amplitude and bandwidth of the signal, each pulsation lasting about 50 msec. The fourth instance, however, was unusual in that the key-down signal exhibited remarkably regular and intense amplitude variations. In all four occurrences, the period of the pulsation was in the range from 0.3 to 0.6 sec. In three occurrences, this period was roughly the same as the one-hop whistler-mode delay along the field-line path; however, no demonstrable mechanism to explain this association could be found. An explanation of pulsations in terms of multipath fading effects could not be supported by the data. More likely explanations include intrinsic oscillation in the emission generation mechanism, natural oscillation in the energetic-particle population, or modulation of the VLF growth rate by Pc 1 micropulsations in the region of wave growth. Other/Unknown Material Antarc* Antarctica NASA Technical Reports Server (NTRS) Cutler ENVELOPE(-60.981,-60.981,-62.612,-62.612) |
institution |
Open Polar |
collection |
NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
07 |
spellingShingle |
07 Bell, T. F. Helliwell, R. A. Pulsation phenomena observed in long-duration vlf whistler-mode signals. |
topic_facet |
07 |
description |
Whistler-mode signals from station NAA (14.7 and 17.8 kHz), Cutler, Maine, show periodic fluctuations (?pulsations') in amplitude and bandwidth. The data were recorded at Eights station, Antarctica, during unmodulated (?key-down') transmissions from NAA lasting up to 2 min. In three of four instances, the pulsations consist of a series of moderate enhancements of the amplitude and bandwidth of the signal, each pulsation lasting about 50 msec. The fourth instance, however, was unusual in that the key-down signal exhibited remarkably regular and intense amplitude variations. In all four occurrences, the period of the pulsation was in the range from 0.3 to 0.6 sec. In three occurrences, this period was roughly the same as the one-hop whistler-mode delay along the field-line path; however, no demonstrable mechanism to explain this association could be found. An explanation of pulsations in terms of multipath fading effects could not be supported by the data. More likely explanations include intrinsic oscillation in the emission generation mechanism, natural oscillation in the energetic-particle population, or modulation of the VLF growth rate by Pc 1 micropulsations in the region of wave growth. |
format |
Other/Unknown Material |
author |
Bell, T. F. Helliwell, R. A. |
author_facet |
Bell, T. F. Helliwell, R. A. |
author_sort |
Bell, T. F. |
title |
Pulsation phenomena observed in long-duration vlf whistler-mode signals. |
title_short |
Pulsation phenomena observed in long-duration vlf whistler-mode signals. |
title_full |
Pulsation phenomena observed in long-duration vlf whistler-mode signals. |
title_fullStr |
Pulsation phenomena observed in long-duration vlf whistler-mode signals. |
title_full_unstemmed |
Pulsation phenomena observed in long-duration vlf whistler-mode signals. |
title_sort |
pulsation phenomena observed in long-duration vlf whistler-mode signals. |
publishDate |
1971 |
url |
http://ntrs.nasa.gov/search.jsp?R=19720029864 |
op_coverage |
Unclassified, Unlimited, Publicly available |
long_lat |
ENVELOPE(-60.981,-60.981,-62.612,-62.612) |
geographic |
Cutler |
geographic_facet |
Cutler |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Other Sources |
op_relation |
http://ntrs.nasa.gov/search.jsp?R=19720029864 Accession ID: 72A13530 |
op_rights |
Copyright |
_version_ |
1766259491792224256 |