Last edited by Yorr
Monday, July 20, 2020 | History

2 edition of Frequency correlation of HF skywave ground backscatter Doppler spectra found in the catalog.

Frequency correlation of HF skywave ground backscatter Doppler spectra

R. Michael Jones

Frequency correlation of HF skywave ground backscatter Doppler spectra

by R. Michael Jones

  • 190 Want to read
  • 39 Currently reading

Published by U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories in [Washington, D.C.?] .
Written in English

    Subjects:
  • Echo scattering layers.,
  • Doppler effect.,
  • Backscattering.

  • Edition Notes

    Other titlesFrequency correlation of H.F. skywave ground backscatter Doppler spectra.
    StatementR.M. Jones, J.P. Riley, T.M. Georges.
    SeriesNOAA technical memorandum ERL WPL -- 115.
    ContributionsRiley, J. P. 1941-, Georges, T. M. 1938-, Environmental Research Laboratories (U.S.)
    The Physical Object
    Paginationv, 83 p. :
    Number of Pages83
    ID Numbers
    Open LibraryOL17830655M

    Wind speed is an important sea surface dynamic parameter which influences a wide variety of oceanic applications. Wave height and wind direction can be extracted from high frequency radar echo spectra with a relatively high accuracy, while the estimation of wind speed is still a challenge. This paper describes an artificial neural network based method to estimate the wind speed in HF . Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on .

    The skywave refers to the signal that travels away from the Earth’s surface towards the ionosphere. Unlike a ground wave it does not follow the contour of the ground, but instead it is directed towards the ionosphere. The angle between the line of the skywave signal and the Earth’s surface at that point may be shallow or steep. For a number of decades, coastal HF radar has been used to remotely measure ocean surface parameters, including waves, at distances exceeding km. The information, which has value in many ocean engineering applications, is obtained using the HF radar cross-section, which relates the directional ocean spectrum to the received radar signal, through a nonlinear integral .

    W, the sea backscatter Doppler spectra were obtained for analysis and correlation with the observed wind speed and direction obtained from R.V. Flip and other ship reports. These data were given to the scientists at SIO for analysis and comparison with the ground .   Near Vertical Incidence Skywave (NVIS) propagation can be used for radio communication in a large area ( km radius) without any intermediate man-made infrastructure. It is therefore especially suited for disaster relief communication, communication in developing regions and applications where independence of local infrastructure is desired, such as .


Share this book
You might also like
Tripoli

Tripoli

RCRA Ground Water Monitoring

RCRA Ground Water Monitoring

silver question

silver question

Keep in Touch

Keep in Touch

study of permanent grassland farms with beef suckler herds recorded by the Meat and Livestock Commission

study of permanent grassland farms with beef suckler herds recorded by the Meat and Livestock Commission

Apollonius of Tyana

Apollonius of Tyana

Perinatal mortality in Humberside.

Perinatal mortality in Humberside.

Enhancing the biological weapons convention

Enhancing the biological weapons convention

Maldives

Maldives

Myths and legends in learning classification rules

Myths and legends in learning classification rules

Better English made easy

Better English made easy

Vocabulary Workshop: Level H, Supplementary Testing Program

Vocabulary Workshop: Level H, Supplementary Testing Program

Lieut. John M. Holmes.

Lieut. John M. Holmes.

art roman en France

art roman en France

Apache Kid

Apache Kid

Frequency correlation of HF skywave ground backscatter Doppler spectra by R. Michael Jones Download PDF EPUB FB2

Get this from a library. Frequency correlation of HF skywave ground backscatter Doppler spectra. [R Michael Jones; J P Riley; T M Georges; Environmental Research Laboratories (U.S.)]. The frequency correlation of Doppler spectra from ionospherically propagated ground backscatter measured on 17 October is presented.

As with direct sea-echo backscatter spectra, there is no significant frequency correlation other than that caused by the window (weighting function) used for the spectral analysis.

This result supports a previous assumption used to analyze skywave Author: R. Jones, J. Riley, T. Georges. For 45 years, men have measured and studied echoes from the distant surface of the earth, obtained with high‐frequency signals (3 to 30 MHz) that travel to and from the scatterers via ionospheric refraction.

During the last five years, much progress has been made in the understanding of this ‘sky‐wave backscatter.’Cited by: Estimating wind speed from HF skywave radar sea backscatter Abstract: Linear expressions relating ocean surface wind speed to a theoretical estimate of the - 10 dB width of the high frequency (HF) sea echo Doppler spectrum ( Hz Doppler shift frequency resolution) are derived for different radar by: 3.

Radar jamming and deception is a form of electronic countermeasures that intentionally sends out radio frequency signals to interfere with the operation of radar by saturating its receiver with noise or false information.

Concepts that blanket the radar with signals so its display cannot be read are normally known as jamming, while systems that produce.

Ship detection with high-resolution HF skywave radar Abstract: This paper presents an overview of ship detection by high-frequency (HF) skywave backscatter over-the-horizon radar (OTHR). Ships have been detected at ranges of km or more by OTHR that uses sufficient resolution in the radar spatial and Doppler frequency domains.

Georges, J. Maresca, The effects of space and time resolution on the quality of sea echo Doppler spectra measured with HF sky wave radar, Radio Science, /RSip, 14, 3, (), (). The frequency correlation of Doppler spectra from ionospherically propagated ground backscatter measured on 17 October is presented.

Statistics at HF skywave ground backscatter Doppler. InCrombie [1] identified that when an electromagnetic wave is transmitted from a shore-based high-frequency (HF) radar, operating at MHz, the Doppler spectrum of sea echo yielded a resonant backscatter phenomenon known as Bragg scattering, which results from coherent reflection of the transmitted energy by ocean surface waves (SWs.

All of these measurements are made using the radar backscatter power spectrum (usually referred to as the Doppler spectrum), which is normally dominated by two peaks resulting from Bragg scatter from linear ocean waves with half the radio wavelength (Barrick ), that is, with the wavenumber given by k sw = 4πgF r /, where F r is the operating frequency of the.

Land-based, high-frequency (HF) surface wave radar has the unique capability of monitoring coastal surface parameters, such as current, waves, and wind, up to km off the coast.

The Doppler spectrum of the backscattered radar signal is characterized by two strong peaks that are caused by the Bragg-resonant scattering from the ocean surface. Remote measurement of the ocean wave frequency spectrum by HF skywave radar (Abstract), Fall Meeting American Geophysical Union, San Francisco, California, December 5–9, Google Scholar Maresca, J.

and C. Carlson. polarisation elements to decompose the skywave signal into power spectra defined over time delay – Doppler – single angle-of arrival – polarisation space (see eg.

[6]). Definition of a comprehensive channel transfer function In the ionosphere, the characteristic time scalesTj of the dynamical processes of interest, {P j}, satisfy the. Doppler spectra as in Fig. 11 with the frequency normalized by the Bragg frequency.

The dashed lines show Doppler spectra simulated using buoy data and Barrick’s second-order theory: (a) cell 4, bearing 1° from north; (b) cellbearing 49° from north (roughly the bore site for the array); and (c) cell bearing 76° from north. The progress of studies on ocean waves using high-frequency (HF) ocean radars is re viewed.

All of the free-wave components are related to the Doppler spectrum of the HF radar. COVID Resources. Reliable information about the coronavirus (COVID) is available from the World Health Organization (current situation, international travel).Numerous and frequently-updated resource results are available from this ’s WebJunction has pulled together information and resources to assist library staff as they consider how to handle.

Unlike the sky-wave connects to W7KP miles to the west, the backscatter data showed significant variations in both the backscatter range and Doppler shift. The backscatter range varied from miles to miles as determined from the propagation time delays assuming the Pactor impulses traveled at the speed of light.

The Doppler spectra of backscattered signal of microwave frequency of GHz were obtained for an upwind-look configuration at a grazing angle of 10˚.

To make another computation of the Doppler frequency for the scatterer velocity, it is necessary to include the speed of the boat where the sensing was performed.

Over-the-horizon radar (OTH), sometimes called beyond the horizon (BTH), is a type of radar system with the ability to detect targets at very long ranges, typically hundreds to thousands of kilometres, beyond the radar horizon, which is the distance limit for ordinary l OTH radar systems were deployed starting in the s and s as part of early warning radar.

Functionality of a HF-OTH skywave radar is strongly dependent upon several factors. Firstly, the propagation channel is highly time-varying, secondly external radio noise is particularly severe and finally, the spectrum avail-ability is limited by the national plan of frequencies.

In this paper we propose a frequency selection method that maxi. In the s the discovery of the skywave (skip) radio propagation method allowed lower power transmitters operating at high frequency to communicate at similar distances by reflecting their radio waves off a layer of ionized atoms in the ionosphere, and long distance radio communication stations switched to the shortwave frequencies.Peak power and missile Range-Doppler echoes map are calculated during the target flight in the boost phase to see whether detection is possible.

2D-ARRAY HF-OTH SKYWAVE RADAR SYSTEM A 2D-array HF radar is a very complex system because it is characterized by a set of features which are very unusual if compared to ordinary microwave radars: 1. As first demonstrated by Barrick for the case of grazing incidence and vertically polarised backscatter, and generalised later by Anderson and Anderson to handle arbitrary bistatic three-dimensional scattering geometries and polarisation states, the HF radar Doppler spectrum D (ω; f, k ^ inc, k ^ scat) of a radiowave of frequency f is related.