The initial study of calibrating receiving digital beam forming in engineering test satellite-9 [International Communications Satellite Systems Conference]

Author(s):  
H. Ono ◽  
E. Sakai ◽  
Y. Inasawa ◽  
M. Kusano ◽  
A. Kanasashi ◽  
...  
1969 ◽  
Vol 73 (700) ◽  
pp. 297-306
Author(s):  
G. K. C. Pardoe

The direct use of satellites is already beginning to have enormous influence on the development of civilisation in our world. An initial study of the benefits to be obtained for mankind by the use of satellites to survey the natural and man-made resources of the earth leads to the inescapable conclusion that this will undoubtedly be one of the major applications of satellite technology that will evolve in the next few years. It is only very few years ago that the real impact of this use of space became evident, but already in that period of time an extremely wide range of types of measurements and different use of such data has been examined and a considerable amount of experimental work been carried out both in earth terrestrial laboratory conditions and also using equipment orbiting in space. There is now a wealth of data on what is possible already and might be possible in this new field of endeavour. I shall attempt in this paper to summarise the main potentialities of different types of systems and try and relate some of the key elements of the satellites to the natural resources being observed.


2014 ◽  
Vol 2014 (1) ◽  
pp. 000816-000819 ◽  
Author(s):  
Tobias Klein ◽  
Peter Uhlig ◽  
Carsten Günner ◽  
Reinhard Kulke

Low Temperature Cofired Ceramics (LTCC) technology is increasingly used for creating high-rel solutions, especially in class S products deployed in space. Current research, executed by the german and european space agencies, focuses inter alia on new, compact beam forming networks for Ka-band multiple feed per beam antennas. These networks consist of a high number of dividers and must provide a high isolation between neighbouring cells to ensure compliance with frequency plan regulations. While the LTCC process brings a number of advantages, its thick film printing process and the tolerances of available resistive paste systems introduce difficulties in implementing typical Wilkinson divider networks. This paper presents a novel concept to implement tolerance-optimized dividers, taking special focus on the properties of the LTCC process.


2020 ◽  
Author(s):  
Dorian Soergel ◽  
Helle Pedersen ◽  
Anne Paul ◽  
Laurent Stehly

<p>Imaging azimuthal anisotropy from seismic noise cross-correlations is challenging, especially in very complex tectonic settings such as the Alps. In this region, the focus has been mainly on retrieving anisotropy using SKS-splitting data, but this data does not provide strong depth constraints. In this work, we map the azimuthal anisotropy of Rayleigh-wave velocity in the Alps using seismic noise cross-correlations. This initial study focusses on waves at ~15 s period. The study area is divided into small zones for which all the stations outside are used as virtual sources and all the stations inside are used as receivers. For each virtual source and each zone, we perform time domain beam forming to retrieve the local phase velocity and propagation direction. As the distances between sources and receivers are relatively small, we use an algorithm that takes into account circular wavefronts. The beam forming shows that the waveforms are very coherent for different stations within each small array, and that deviations from great-circle propagation can be significant. The resulting phase velocities in each zone show a variation with azimuth which is in some locations very small (indicating that anisotropy is insignificant) and which in all other locations has a 2<span>θ</span> dependency on azimuth, indicative of well resolved azimuthal anisotropy. Bootstrapping uncertainty estimates show that the results are very stable if a sufficient number of source stations is used. The combination of permanent stations with the temporary AlpArray stations provides us with a very high station density that allows us to carry out this measurement across a large area. The resulting anisotropy maps show a good resolution, with higher uncertainties in the Po plain and the areas of low station density. The clear 2<span>θ</span> azimuth dependency is a sign that our method overcomes both effects related to source directivity (which has an approximate 1<span>θ</span> dependency) and measurement instability which can be significant for Eikonal tomography in the case of irregular networks.</p>


Author(s):  
Piero Angeletti ◽  
Stefano Cioni ◽  
Jerome Tronc ◽  
Claudio Campa ◽  
Filippo Di Cecca ◽  
...  

Author(s):  
D.R. Jackson ◽  
J.H. Hoofnagle ◽  
A.N. Schulman ◽  
J.L. Dienstag ◽  
R.H. Purcell ◽  
...  

Using immune electron microscopy Feinstone et. al. demonstrated the presence of a 27 nm virus-like particle in acute-phase stools of patients with viral hepatitis, type A, These hepatitis A antigen (HA Ag) particles were aggregated by convalescent serum from patients with type A hepatitis but not by pre-infection serum. Subsequently Dienstag et. al. and Maynard et. al. produced acute hepatitis in chimpanzees by inoculation with human stool containing HA Ag. During the early acute disease, virus like particles antigenically, morphologically and biophysically identical to the human HA Ag particle were found in chimpanzee stool. Recently Hilleman et. al. have described similar particles in liver and serum of marmosets infected with hepatitis A virus (HAV). We have investigated liver, bile and stool from chimpanzees and marmosets experimentally infected with HAV. In an initial study, a chimpanzee (no.785) inoculated with HA Ag-containing stool developed elevated liver enzymes 21 days after exposure.


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