Fiber-Optic Components For Satellite T&C Systems

Abstract

The applicability of a fiber -optic telemetry and command (T &C) system for a large communications satellite system is analyzed. This system is characterized by low bit rates (below 1 Mbit /s) and relatively short transmission distances (below 20 meters). Various LAN (local area network) architectures and required components are examined for this application. The most suitable system is found to be a transmissive star network using LEDs, PIN detectors, and large size multi -mode optical fibers. This system is competitive in power and mass for certain T &C applications with conventional wire systems but offer a much higher immunity to electromagnetic interference. A new optical rotary joint, required for spin -stabilized satellite applications, is discussed.

Effect of EDTA on Growth of 4-Dimethylamino-N-Methyl-4-Stilbazolium Tosylate Crystals by Slope Nucleation Method

“…Furthermore, the crystals grown at the higher saturation temperature (40 C) were found to be thicker, whereas the crystals grown at the lower temperature (35 C) were thinner. This was also consistent with the observation by Sasaki's group 18) as well as with the Jackson -factor theory. 27) According to the Jackson'sfactor theory, i.e., ¼ ÁS=R $ ÁH sol =RT, crystal growth at a lower temperature can have a large -factor, so that the crystals grown could have larger faces (more platelike).…”

“…At a low growth temperature, very thin crystals have been obtained using SNM by Sasaki's group in Japan. 18) The use of an effective solvent is another method. Rai et al 19) also tested a methanol/ethanol mixed solvent, and observed that metastable zone width 20) increases with increasing ethanol percentage in the solvent.…”

Fluctuation effects in underdoped cuprate superconductors under a magnetic field

“…However, the corresponding uncorrelated behavior seen in the electron-doped materials [5] with σ n of the same order as in the optimally doped YBCO [3] is intrinsic, and its origin needs to be attributed to a fluctuation property. Similar behaviors have been also found in overdoped La 2−x Sr x CuO 4 (LSCOx) [7] and κ-(ET) 2 organic superconductors [8,9]. As argued elsewhere [10] by fitting to data [9], the main origin is expected to consist in the quantum dynamical nature, enhanced with increasing the field, of the SC fluctuation.…”

“…From Fig.1, such a mean field argument on the sharp drop of ρ is generally invalid, since a picture based on an anomalous feature near the vortex cores would become more applicable with underdoping, while a comparison between the ρ and N -data in high fields in Fig.1 clearly shows that the decrease of N at lower temperatures is due not to ρ but to s φ . As mentioned in Introduction, a sharp drop of ρ much below H * c2 (T ) (≤ H 0 (T )) occurs even in organic materials [9,10] and is due not to a mechanism peculiar to the cuprates but to a 3D VG transition in systems with a large quantum SC fluctuation.…”

Inositol polyphosphates, diphosphoinositol polyphosphates and phosphatidylinositol polyphosphate lipids: Structure, synthesis, and development of probes for studying biological activity

“…No inhibition of the 4-phosphatase activity of INPP4 was observed for this analog. 241 A potentially interesting modification that has rarely been reported is the synthesis of fluoromethylene or difluoromethylene phosphonate analogs in which the inositol oxygen is replaced by CHF or CF 2 . This has the potential to control the pK a of the resulting phosphonate while retaining the two free oxygens of the natural phosphate.…”