نتایج جستجو برای: vhf circuit

تعداد نتایج: 118032  

2005
F. Onoma Y. Otsuka K. Shiokawa T. Ogawa M. Yamamoto S. Fukao S. Saito

We report simultaneous observations of atmospheric gravity waves (AGW) in OI (557.7 nm) and OH airglow images and VHF radar backscatter from field-aligned irregularities (FAI) in the E-region during the SEEK-2 (Sporadic-E Experiment over Kyushu 2) campaign period from 29 July to 9 August 2002. An all-sky imager was operated at Nishino-Omote (30.5 N, 130.1 E), Japan. On 14 nights, 17 AGW events ...

Journal: :Hamostaseologie 2008
P Aleksandrowicz K Wolf D Falzarano H Feldmann J Seebach H Schnittler

Pathogenesis of viral haemorrhagic fever (VHF) is closely associated with alterations of the vascular system. Among the virus families causing VHF, filoviruses (Marburg and Ebola) are the most fatal, and will be focused on here. After entering the body, Ebola primarily targets monocytes/macrophages and dendritic cells. Infected dendritic cells are largely impaired in their activation potency, l...

2010
H. Oriot P. Dubois-Fernandez

The SETHI sensor from ONERA is an airborne radar equipped with different bands (UHF-VHF, L, X) on a Falcon 20. The UHF-VHF band is fully polarimetric and can operate between 225 MHz up to 460MHz. In August 2009, this system was used in French Guiana for the TROPISAR experiment. Data were acquired from 0◦ incidence angle up to 65◦ incidence angle and a swath of about 6000 m. The antenna pattern ...

1999
S. E. Milan

Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations ...

Journal: :Journal of neurology, neurosurgery, and psychiatry 1987
S Z Rapcsak R T Watson K M Heilman

Visual extinction was studied in a patient with neglect from a right hemispheric lesion. Extinction occurred during double simultaneous stimulation within the same visual hemi-field (VHF). This finding suggests that interhemispheric rivalry is not a critical factor. During double simultaneous stimulation within the same VHF as well as with stimuli in different VHFs, the severity of extinction w...

2009
Y. S. Meng Y. H. Lee B. C. Ng

In this paper, rainfall effect on the VHF radio-wave propagation in a tropical forest is further studied in details. Theoretical study and experimental investigations are performed with the help of a four-layered model for forested environment. It is found that the lateral wave traveling along the air-canopy interface, the direct waves, and the ground reflected waves are the main modes for VHF ...

2005
R. M. Worthington

Thin stable atmospheric layers cause VHF radars to receive increased echo power from near zenith. Layers can be tilted from horizontal, for instance by gravity waves, and the direction of VHF “glinting” is measurable by spatial domain interferometry or many-beam Doppler beam swinging (DBS). This paper uses the Middle and Upper atmosphere (MU) radar, Shigaraki, Japan as a volume-imaging radar wi...

Journal: :Journal of Physics: Conference Series 2021

2011
S. Close A. Fletcher M. Dunham I. Linscott

[1] We have developed a new method for extracting ionospheric parameters from broadband RF data collected in low‐Earth orbit using coherent matched filters. The coherent matched filter uses the full time series of the electric field and matches the Fourier transform of these data with an ionospheric transfer function. This approach was applied to both lightning and human‐made data transmitted o...

2011
GEORGE MASTORAKIS

The current global move to switch from analogue to digital terrestrial television has opened up an opportunity for the re-allocation of valuable spectrum resources in VHF/UHF frequencies. In one way, spectrum bands once used for analogue TV broadcasting will be completely cleared, leaving a space for deploying new licensed wireless services, and in another way, digital terrestrial television te...

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