Communication satellite technology trends

A chronology of space-Earth interconnectivity is presented. The Advanced Communications Technology Satellite (ACTS) system, Land Mobile Satellite, space-Earth antennas, impact of antenna size on coverage, intersatellite links are outlined. This presentation is represented by graphs and charts only

Rapid, room-temperature, solvent-free mechanochemical oxidation of elemental gold into organosoluble gold salts

Gold is highly valued for a wide range of commercial and technological applications but is processed exclusively through highly aggressive and toxic solvents and/or reagents, ultimately yielding water-soluble salts that are difficult to separate from inorganic reaction byproducts. As a result, development of safer, cleaner processes that would enable gold processing in non-aqueous, organic solvent is an attractive technological goal. Here, we describe a methodology that simultaneously avoids aggressive reagents and enables gold extraction into a safe organic solvent. The methodology is based on solventless, mechanochemical oxidation of metallic gold with Oxone® in the presence of tetraalkylammonium halide salts, to directly, rapidly (within 30–60 minutes) and at room temperature convert gold metal into solid salts that are immediately soluble in pure organic solvents and aqueous alcoholic media. The organosoluble gold salts are easily separated from sulfate byproducts by direct extraction into the benign solvent ethyl acetate, which is also easily recycled for re-use, providing a strategy for gold activation and dissolution without any additional reagents for purification, such as cation exchange resins, salts, or chelating agents. Besides enabling direct extraction of gold into an organic solvent, the mechanochemically obtained organosoluble gold salts can also be readily used for further syntheses, as shown here by a two-step one-pot route to prepare air- and moisture-resistant Au(i) salts, and an improved synthesis of gold nanoparticles from bulk gold

VLSI IN MILITARY COMMUNICATIONS

International Telemetering Conference Proceedings / October 13-15, 1981 / Bahia Hotel, San Diego, CaliforniaInternational Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

A History of Commercial Earth Terminals

International Telemetering Conference Proceedings / October 14-16, 1980 / Bahia Hotel, San Diego, CaliforniaThis paper will discuss the evolution of the communication satellite earth terminal from the standpoint of both user requirements and cost. It will start with the TELSTAR earth terminal and discuss the costs and structures of the early Intelsat and COMSAT earth terminals built in the 1960's. The paper will then trace the cost evolution to the 1970's with the introduction of Standard B and C terminals, 4.5 and 10 meter TVRO earth terminals; domestic earth terminals for communications and data in all parts of the world; and finally the new 56 K bps 5 meter terminals, the SBS terminals, and the direct-to-user terminals (TVRO) of the 1980's.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

The Impact of Phase Noise in Digital Satellite Communications

International Telemetering Conference Proceedings / September 28-30, 1982 / Sheraton Harbor Island Hotel and Convention Center, San Diego, CaliforniaMany military and commercial satellite communication links are being used which utilize standard or staggered QPSK. At bit rates below one megabit, these links operate in environments which produce two types of impairments–continuous and random--which determine the final bit error rate and data throughput. This paper will discuss the impact of random phase jitter which is a major impairment which can be contributed at every point in the link. This phase jitter can cause significant phase and timing errors at the receiver output and can even lead to drop-outs of key terminal equipments. The various sources of phase jitter will be discussed and related to system performance. Particular emphasis will be made of the contributions of scintillation and random atmospheric effects and by equipment malfunctions to phase noise which can cause not only periods of increase in bit and timing error, but also clock slippage and I/C reversal which can cause decoders description and demultiplexers to become inoperative. This paper will also include considerations of cochannel and adjacent channel interference on phase jitter.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Biophysical properties of dimeric phospholipids

A series of unusual bipolar and bis-phospholipids (dimeric phospholipids) have been studied. The structure, conformation, morphology and biophysical properties of the resulting phospholipid aggregates were investigated.Deuterium magnetic resonance spectroscopy ($sp2$H NMR) was used to study and characterize the conformation and acyl chain order in oriented bipolar lipid membranes. The $sp2$H-NMR studies indicated a large and constant value for the order parameter (S$rm sb{mol})$ for all positions along the bipolar lipid diacyl chain for mechanically oriented, magnetically oriented and unoriented samples. This indicates that the great majority ($>$90%) of the bipolar lipid exists in a highly ordered spanning conformation.Dimeric phospholipid aggregate morphologies were studied using $sp{31}$P NMR, small angle X-ray scattering, electron microscopy, differential scanning calorimetry, and the Langmuir film balance technique in order to study the relationship between lipid structure and aggregate morphology. Dimeric phospholipids favour a lamellar morphology. A number of lipid structure-dependent features have been observed including tri-lamellar structures, extended ripple phases and hexagonal phases.Dimeric and non-hydrolyzable phospholipids were used to study the phenomenon of interfacial activation of extracellular phospholipase A$sb2$ (EC. 3.1.1.4) (PLA$sb2)$ in relation to lipid phase, substrate conformation and mobility. Kinetic results and product analyses are consistent with a situation where the spanning conformer of bipolar phospholipids is resistant to PLA$sb2$-catalyzed hydrolysis but the hairpin conformer is readily hydrolyzed. Finally, an analysis of interfacial kinetics in non-hydrolyzable matrices indicated varying degrees of interfacial inhibition and hydrolysis product activation. This has not been explicitly recognized before and affects the choice of assay conditions for PLA$ sb2.

A Survey of Modern Instrumentation in Aerospace TT&C Earth Terminals

International Telemetering Conference Proceedings / October 13-15, 1981 / Bahia Hotel, San Diego, CaliforniaThis paper will provide an overview of the instrumentation of aerospace telemetry/systems in mobile and stationary earth terminals, using integrated circuits and LSI technology, microprocessors, computer graphics and measurement system. This instrumentation includes not only circuits to handle TT&C data, but also to analyze display and control system performance from the RF portion including considerations of sensitivity and effective radiated power, to tracking measurements, baseband and data system performance; to man-machine interfaces. This paper will also discuss modern display systems and techniques and will introduce the advantages of the use of the IEEE standard 488-1978 and RS-232 interface buses for the control and monitoring of TT&C equipment, including data processing with particular application to survivable earth terminals.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

ENHANCEMENT OF ENDURABILITY BY MODERN TECHNOLOGY IN TRANSPORTABLE MILITARY TT&C GROUND TERMINALS

International Telemetering Conference Proceedings / October 13-15, 1981 / Bahia Hotel, San Diego, CaliforniaInternational Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Imaging the Selective Binding of Synapsin to Anionic Membrane Domains

Synapsins are membrane-associated proteins that cover the surface of synaptic vesicles and are responsible for maintaining a pool of neurotransmitter-loaded vesicles for use during neuronal activity. We have used atomic force microscopy (AFM) to study the interaction of synapsin I with negatively charged lipid domains in phase-separated supported lipid bilayers prepared from mixtures of phosphatidylcholines (PCs) and phosphatidylserines (PSs). The results indicate a mixture of electrostatic binding to anionic PS-rich domains as well as some nonspecific binding to the PC phase. Interestingly, both protein binding and scanning with synapsin-coated AFM tips can be used to visualize charged lipid domains that cannot be detected by topography alone.NRC publication: Ye