Results 161 to 170 of about 413,548 (214)

Doppler characteristics of HF spread Doppler clutter recorded at Alice Springs, Australia

Advances in Space Research, 2021
Abstract Mean night-time peak power, Doppler shift and Doppler width of spread Doppler clutter (SDC) received by a high frequency backscatter radar located at Alice Springs, Australia from 2000 to 2018 is presented as a function of azimuth, sunspot number, time of year and frequency.
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HF Doppler observations associated with spread F

Journal of Geophysical Research: Space Physics, 1979
This paper discusses HF Doppler spectrum observations at mid‐latitudes when spread F was observed on local ionograms. The data indicate that Doppler broadening is related to spread F (they both commence simultaneously). The results can be simulated by using different ionospheric models.
D. W. Cornelius, E. A. Essex
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Doppler selection of HF radiosignals on long paths

Geomagnetism and Aeronomy, 2007
The long-term registration of the Doppler spectra of HF radiosignals has been performed on the Moscow-Akademik Vernadsky Ukrainian Antarctic station path. It has been revealed that the spectra are split when the solar terminator crosses direct and return radio lines.
A. V. Zalizovskii, V. G. Galushko, A. S. Kashcheev, A. V. Koloskov, Yu. M. Yampolski, I. B. Egorov, A. V. Popov   +6 more
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The statistics of HF sea-echo Doppler spectra

IEEE Transactions on Antennas and Propagation, 1977
Several important statistical properties of the HF sea echo and its Doppler power spectrum, which are useful in optimizing the design of radar oceanographic experiments, are established. First- and second-order theories show that the echo signal (e.g., the voltage) should be Gaussian; this is confirmed with experimental surface-wave data i) by ...
D. Barrick, J. Snider
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The remote HF-Doppler detection of the sunrise effect

2006 Asia-Pacific Microwave Conference, 2006
The information about the ionospheric change is of great significance for the research of geophysical phenomenon and the communication guidance. In this paper, according to the year-round data of the HF-Doppler detection of the ionosphere, we induced and generalized the curves of Doppler frequency shift during the sunrise and analyzed the basic ...
null Zhang Yinghui, null Wang Yizhuo
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GLRT-Based Adaptive Doppler Processing for HF Radar Systems

2007 IEEE International Conference on Acoustics, Speech and Signal Processing - ICASSP '07, 2007
High frequency skywave and surface-wave over-the-horizon (OTH) radars are required to detect targets in the presence of powerful clutter and interference from man-made and natural sources. However, the received disturbances may be highly structured in the time domain (i.e. pulse-to-pulse) within the coherent processing interval (CPI).
Giuseppe A. Fabrizio, Alfonso Farina
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Experimental Evaluation of the Range–Doppler Coupling on HF Surface Wave Radars

IEEE Geoscience and Remote Sensing Letters, 2013
High-frequency surface wave radar (HFSWR) is used in oceanography to monitor surface wind waves and currents and, more recently, to detect ships in maritime surveillance. The radar accuracy is affected by range-Doppler coupling, which yields a displacement in the measured range proportional to the target radial velocity, i.e., the Doppler shift in the ...
Luigi Bruno, Paolo Braca, Jochen Horstmann, Michele Vespe   +3 more
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The Calculation of Ionospheric Doppler Spread on HF Communication Channels

IEEE Transactions on Communications, 1975
Using some basic concepts of ionospheric propagation, multipath and Doppler spread calculations are obtained for the HF ionospheric communication channel. Because of sensitivity to the solar control mechanism, the Doppler spread results are found to demonstrate a pronounced dependence on time of day and operating frequency.
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Doppler shift estimation for HF channels based on TEC measurements

2015 23nd Signal Processing and Communications Applications Conference (SIU), 2015
Communication over long distances in an HF channel is established through ionospheric propagation. Ionosphere continuously changes due to both the effect of the sun and also other causes such as geomagnetic storms and drift. Therefore, instantaneous knowledge of the state of ionosphere has an inevitable effect on the link quality.
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HF Doppler studies of traveling ionospheric disturbances

Journal of Atmospheric and Terrestrial Physics, 1968
Abstract Wavelike ionospheric motions observed with a network of CW Doppler sounders are analyzed and found to fall into four separate classes not previously distinguished. The motions of each type are attributed to various kinds of atmospheric waves that interact with the ionosphere.
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