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Sky-wave backscatter - A means for observing our environment at great distances.During the last five years, much progress has been made in the understanding of sky-wave backscatter. An explanation of the various interacting phenomena is presented, as is a review of the current state of knowledge reflecting recent advances in observational methods and analytic techniques. New narrow-beam antennas, coupled with signal modulations that permit fine resolution in time delay, are beginning to yield information concerning the character of the scatterers, which now can be separately discerned. These narrow beams also permit study of polarization fading from small regions, and this shows promise as a means for learning the distant sea state. Doppler shifts of a fraction of a hertz on signals of tens of megahertz are separable, permitting isolation of sea returns from ground returns by virtue of the Doppler effect resulting from sea-wave speed; this also suggests a potential sea-monitoring principle. Despite these advances, there is little practical application of sky-wave backscatter as a means of environmental monitoring. This lack is attributed to the large remaining gaps in our understanding of the echoes and our inability to interpret the forms of data that can be acquired with equipment of reasonable cost.
Document ID
19720037827
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Croft, T. A.
(Stanford University Stanford, Calif., United States)
Date Acquired
August 6, 2013
Publication Date
February 1, 1972
Publication Information
Publication: Reviews of Geophysics and Space Physics
Volume: 10
Subject Category
Communications
Accession Number
72A21493
Funding Number(s)
CONTRACT_GRANT: NGL-05-020-014
Distribution Limits
Public
Copyright
Other

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