Spectral characteristics of HF ground backscatter

Earl, G. F.; Bourne, I. A.

doi:10.1016/0021-9169(75)90126-9

Cited by 6 publications

(2 citation statements)

References 18 publications

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“…An outline of the experimental technique used to make spectral measurements on ground backscatter echos has been given recently by Earl and Bourne (1975). The essential point is that the signal at a given delay is made up of echos from scatterers in a volume whose depth is of the order of half the pulse length of the transmitter.…”

Section: Experimental Techniquementioning

confidence: 99%

“…The spectral characteristics of ionospherically propagated ground backscatter echos are potentially capable of yielding information about rates of change in remote regions of the Earth's ionosphere and the surface of the sea (Crombie 1955;Croft 1972;Earl and Bourne 1975). If this potential is to be realized, the mechanism giving rise to the spectral characteristics must be understood.…”

Section: Introductionmentioning

confidence: 99%

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On the Interpretation of the Doppler Spectra of Ionospherically Propagated Ground Backscatter Echoes

Bennett¹

1975

Aust. J. Phys.

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The mechanism giVing rise to the backscatter Doppler spectrum is discussed by means of a simple model. Attention is focused on the effect of movement of the region contributing to the echo which arises from time changes in the group velocity within the ionosphere. It is shown that the influence of these changes on the spectrum can be separated into two parts: (1) A change in the maximum possible width of the spectrum as a result of the change of the time for which an indiVidual scatterer is contributing to the echo; this effect is independent of the scatterer distribution. (2) A possible narrowing of the spectrum as a result of the way in which the signals from individual scatterers combine; this effect depends upon scatterer distribution. Scatter from a fixed'scattering surface and from dispersive waves (e.g. sea waves) is considered. A tentative extrapolation of the results to a more realistic model suggests that neither effect is likely to be significant in practical highfrequency radio experiments (except at short ranges with highly directional antennas), although they may be significant in acoustic wave simulations of the radio case.

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Section: Experimental Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Interpretation of the Doppler Spectra of Ionospherically Propagated Ground Backscatter Echoes

Bennett¹

1975

Aust. J. Phys.

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Synthesis of HF ground backscatter spectral characteristics

Earl

1975

Journal of Atmospheric and Terrestrial Physics

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A resolution limitation on sea‐echo radar spectra inferred from point to point ionospheric Doppler broadening

Heron¹,

Rose²

1978

Geophysical Research Letters

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A 12 MHz radio path over 2000 km has been used to examine the stability of the transmitted frequency over intervals of time generally needed to take a sea state measurement of the ocean surface on a radar backscatter experiment. The variance of observed ionospheric Doppler shifts during successive 100 second intervals is about 0.04 Hz for one hop, point to point propagation predominantly through the F layer. This is expected to double for backscatter paths and to be directly proportional to the carrier frequency. Although the observations apply directly to only one ray in the radar beam and exclude mixed modes on the return path, they indicate a resolution limitation on the second‐order spectra from which sea state conditions may be calculated.

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Spectral characteristics of HF ground backscatter

Cited by 6 publications

References 18 publications

On the Interpretation of the Doppler Spectra of Ionospherically Propagated Ground Backscatter Echoes

On the Interpretation of the Doppler Spectra of Ionospherically Propagated Ground Backscatter Echoes

Synthesis of HF ground backscatter spectral characteristics

A resolution limitation on sea‐echo radar spectra inferred from point to point ionospheric Doppler broadening

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