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Results for “CARRIER MODULATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Macromolecular crystal growing system

A macromolecular crystal growing system especially designed for growing crystals in the low gravity of space as well as the gravity of earth includes at least one tray assembly, a carrier assembly which receives the tray, and a refrigeration-incubation module in which the carrier assembly is received. The tray assembly includes a plurality of sealed chambers with a plastic syringe and a plug means for the double tip of the syringe provided therein. Ganging mechanisms operate the syringes and plugs simultaneously in a precise and smooth operation. Preferably, the tray assemblies are mounted on ball bearing slides for smooth operation in inserting and removing the tray assemblies into the carrier assembly. The plugging mechanism also includes a loading control mechanism. A mechanism for leaving a syringe unplugged is also provided.

Snyder, Robert S.↗
NASA NTRS2011

Flexible, reconfigurable, power efficient transmitter and method

A flexible, reconfigurable, power efficient transmitter device and method is provided. In one embodiment, the method includes receiving outbound data and determining a mode of operation. When operating in a first mode the method may include modulation mapping the outbound data according a modulation scheme to provide first modulation mapped digital data, converting the first modulation mapped digital data to an analog signal that comprises an intermediate frequency (IF) analog signal, upconverting the IF analog signal to produce a first modulated radio frequency (RF) signal based on a local oscillator signal, amplifying the first RF modulated signal to produce a first RF output signal, and outputting the first RF output signal via an isolator. In a second mode of operation method may include modulation mapping the outbound data according a modulation scheme to provide second modulation mapped digital data, converting the second modulation mapped digital data to a first digital baseband signal, conditioning the first digital baseband signal to provide a first analog baseband signal, modulating one or more carriers with the first analog baseband signal to produce a second modulated RF signal based on a local oscillator signal, amplifying the second RF modulated signal to produce a second RF output signal, and outputting the second RF output signal via the isolator. The digital baseband signal may comprise an in-phase (I) digital baseband signal and a quadrature (Q) baseband signal.

Bishop, James W.↗
NASA NTRS2008

Ka-Band Transponder for Deep-Space Radio Science

A one-page document describes a Ka-band transponder being developed for use in deep-space radio science. The transponder receives in the Deep Space Network (DSN) uplink frequency band of 34.2 to 34.7 GHz, transmits in the 31.8- to 32.3 GHz DSN downlink band, and performs regenerative ranging on a DSN standard 4-MHz ranging tone subcarrier phase-modulated onto the uplink carrier signal. A primary consideration in this development is reduction in size, relative to other such transponders. The transponder design is all-analog, chosen to minimize not only the size but also the number of parts and the design time and, thus, the cost. The receiver features two stages of frequency down-conversion. The receiver locks onto the uplink carrier signal. The exciter signal for the transmitter is derived from the same source as that used to generate the first-stage local-oscillator signal. The ranging-tone subcarrier is down-converted along with the carrier to the second intermediate frequency, where the 4-MHz tone is demodulated from the composite signal and fed into a ranging-tone-tracking loop, which regenerates the tone. The regenerated tone is linearly phase-modulated onto the downlink carrier.

Dennis, Matthew S.↗
NASA NTRS1998

Spread-Spectrum Carrier Estimation With Unknown Doppler Shift

We present a method for the frequency estimation of a BPSK modulated, spread-spectrum carrier with unknown Doppler shift. The approach relies on a classic periodogram in conjunction with a spectral matched filter. Simulation results indicate accurate carrier estimation with processing gains near 40. A DSP-based prototype has been implemented for real-time carrier estimation for use in New Mexico State University's proposal for NASA's Demand Assignment Multiple Access service.

DeLeon, Phillip L.↗
DOE OSTI2018

The importance of the membrane interface as the reference state for membrane protein stability

The insertion of nascent polypeptide chains into lipid bilayer membranes and the stability of membrane proteins crucially depend on the equilibrium partitioning of polypeptides. For this, the transfer of full sequences of amino-acid residues into the bilayer, rather than individual amino acids, must be understood. Earlier studies have revealed that the most likely reference state for partitioning very hydrophobic sequences is the membrane interface. We have used μs-scale simulations to calculate the interface-to-transmembrane partitioning free energies ΔG S→TM for two hydrophobic carrier sequences in order to estimate the insertion free energy for all 20 amino acid residues when bonded to the center of a partitioning hydrophobic peptide. Our findings reflect that prior single-residue scales likely overestimate the partitioning free energies of polypeptides. The correlation of ΔG S→TM with experimental full-peptide translocon insertion data is high, implying an important role for the membrane interface in translocon-based insertion. The choice of carrier sequence greatly modulates the contribution of each single-residue mutation to the overall partitioning free energy. Our results demonstrate the importance of quantifying the observed full-peptide partitioning equilibrium, which is between membrane interface and transmembrane inserted, rather than combining individual water-to-membrane amino acid transfer free energies.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Reversible conversion of dominant polarity in ambipolar polymer/graphene oxide hybrids

The possibility to selectively modulate the charge carrier transport in semiconducting materials is extremely challenging for the development of high performance and low-power consuming logic circuits. Systematical control over the polarity (electrons and holes) in transistor based on solution processed layer by layer polymer/graphene oxide hybrid system has been demonstrated. The conversion degree of the polarity is well controlled and reversible by trapping the opposite carriers. Basically, an electron device is switched to be a hole only device or vice versa. Finally, a hybrid layer ambipolar inverter is demonstrated in which almost no leakage of opposite carrier is found. We conclude that this hybrid material has wide range of applications in planar p-n junctions and logic circuits for high-throughput manufacturing of printed electronic circuits.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Design rules for dynamic-template-directed crystallization of conjugated polymers

The multiscale morphology and device performance of printed semiconducting polymers are highly sensitive to the substrate/ink interfacial properties during solution coating. There is an urgent need for general design rules correlating the substrate properties and conjugated polymer (CP) morphology, which do not yet exist. Dynamic surfaces are particularly promising for templating highly crystalline and highly aligned conjugated polymer thin films and have been shown in recent studies. In this work, we implement the dynamic-templating method using a series of liquid-infused nanoporous substrates as a tool to study the impact of template reconfigurability and chemistry on the multiscale morphology of conjugated polymer thin films, using a high performing donor–acceptor polymer (DPP-BTz) as a model compound. By quantifying the enthalpy of adsorption, we demonstrate that the strength of template–CP interactions directly measures the effectiveness of dynamic surfaces in promoting conjugated polymer crystallization and alignment. We further show that the enthalpy of interactions increases by enhancing the template dynamics and is sensitively modulated by template chemistry. Specifically, increasing the template–CP interactions leads to a larger domain size and higher degree of crystallinity in templated conjugated polymer thin films prepared by meniscus-guided solution coating. This observation validates our hypothesis that dynamic templates function by promoting the nucleation of conjugated polymers. We also demonstrate that such dynamic-template-dependent morphology is independent of coating speed. Notably, the enhanced morphological properties modulate the charge carrier mobility in field-effect transistors (FETs) over an order of magnitude reaching a hole mobility of 2.8 cm 2 V –1 s –1 . This work is a significant step towards establishing general guidelines on how the substrate–ink interfacial properties influence morphology and performance of solution coated CP thin films.

42 ENGINEERING↗
DOE OSTI2020

Transient work function gating: A new photoemission regime

We present the theoretical basis for a new photoemission regime, transient work function gating (TWFG), which temporally and energetically gates photoemission and produces near-threshold photoelectrons with thermally limited emittance, percent-level quantum efficiency, and control over temporal coherence. The technique consists of actively gating the work function of a generalized photocathode using a non-ionizing long-wavelength optical field to produce an adiabatic modulation of the carrier density at their surface. We examine TWFG as a means to circumvent the long-standing trade-off between low emittance and high quantum efficiency, untethered to particle source or photocathode specifics. TWFG promises new opportunities in photoemission physics for next generation electron and accelerator-based x-ray photon sources.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Magnetism of Complex Oxide Interfaces

This chapter reviews theoretical studies focused on interfaces or heterostructures of complex oxides such as perovskite transition-metal oxides (TMO). It describes examples of such theoretical studies of TMO interfaces employing a variety of methods. The chapter explains theoretical work at the interfaces of a ferroelectric and a magnetic manganite and provides rules to judge the type of coupling between the spins at opposite sides of the interfaces. It shows how the electric field of the ferroelectric component affects the electronic density of the other component, typically a metallic manganite, thus altering its transport properties and sometimes even inducing a phase transition. The chapter explores the puzzling exchange bias effect is addressed for the interfaces involving a ferromagnet on one side and a G-type antiferromagnetic state on the other. If the interfacial carrier density is modulated away from the region, the ferromagnetism and transport will become worse.

Okamoto, Satoshi↗
DOE OSTI2013

Electric Vehicle Communications Standards Testing and Validation - Phase II: SAE J2931/1

Vehicle to grid communication standards enable interoperability among vehicles, charging stations and utility providers and provide the capability to implement charge management. Several standards initiatives by the Society of Automobile Engineers (SAE), International Standards Organization and International Electrotechnical Commission (ISO/IEC), and ZigBee/HomePlug Alliance are developing requirements for communication messages and protocols. Recent work by the Electric Power Research Institute (EPRI) in collaboration with SAE and automobile manufacturers has identified vehicle to grid communication performance requirements and developed a test plan as part of SAE J2931/1 committee work. This laboratory test plan was approved by the SAE J2931/1 committee and included test configurations, test methods, and performance requirements to verify reliability, robustness, repeatability, maximum communication distance, and authentication features of power line carrier (PLC) communication modules at the internet protocol layer level. The goal of the testing effort was to select a communication technology that would enable automobile manufacturers to begin the development and implementation process. The EPRI/Argonne National Laboratory (ANL)/Pacific Northwest National Laboratory (PNNL) testing teams divided the testing so that results for each test could be presented by two teams, performing the tests independently. The PNNL team performed narrowband PLC testing including the Texas Instruments (TI) Concerto, Ariane Controls AC-CPM1, and the MAXIM Tahoe 2 evaluation boards. The scope of testing was limited to measuring the vendor systems communication performance between Electric Vehicle Support Equipment (EVSE) and plug-in electric vehicles (PEV). The testing scope did not address PEV’s CAN bus to PLC or PLC to EVSE (Wi-Fi, cellular, PLC Mains, etc.) communication integration. In particular, no evaluation was performed to delineate the effort needed to translate the IPv6/SEP2.0 messages to PEV’s CAN bus. The J2931/1 laboratory test results were presented to the SAE membership on March 20-22, 2012. The SAE committee decided to select HomePlug GreenPHY (HPGP) as the communication technology to use between the PEV and EVSE. No technology completely met all performance requirements. Both the MAXIM Tahoe 2 and TI Concerto met the 100Kbps throughput requirement, are estimated to meet the latency measurement performance, and met the control pilot impairment requirements. But HPGP demonstrated the potential to provide a data throughput rate of 10x of the requirement and either met or showed the potential to meet the other requirements with further development.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2019

Microscopy of Electrostatic Field Effect in Novel Quantum Materials (Final Report)

In this DOE Early Career project “Microscopy of Electrostatic Field Effect in Novel Quantum Materials”, the PI’s group explored the nanoscale electronic properties when charge carriers are electrostatically modulated in functional materials. Using a microwave impedance microscope (MIM), the team probed the spatial evolution of local conductivity in various field-effect transistors (FETs) ranging from traditional metal-oxide-semiconductor FETs, sketched oxide-interface FETs, to ferroelectric FETs and electric double-layer transistors (EDLTs). Specifically, the work has led to a deep understanding on the electrical inhomogeneity and conductive edge channels in atomically thin transition metal dichalcogenides and their heterostructures, which is of fundamental importance for their applications in electronics and photonics. The unique sub-surface imaging capability also enables the first-time report of ferroelectric field effect on Ge substrates due to the polarization switching of an epitaxial BaTiO 3 layer, as well as the visualization of sketched nanostructures in the LaAlO 3 /SrTiO 3 interface. Using a cryogenic MIM, the local channel conductance in ion-gel-gated oxide EDLTs has been successfully imaged, resolving a major challenge in the EDLT research to study electronic fluctuations in the devices. Finally, a new tuning-fork-based MIM has been developed to perform quantitative conductivity imaging on back-gated FETs. The research supported by this DOE grant is significant for understanding the nanoscale uniformity in technologically important materials towards energy applications.

2D materials↗
NASA NTRS1963

Command and telemetry systems

The command and telemetry portions of the Telstar system provide necessary support functions for the basic communications experiment and the radiation experiment. By means of the command system, the states of 9 magnetic latching relays in the satellite are controlled from the ground. Commands are sent to the satellite by coded signals modulated on a carrier in the VHF band. The telemetry system also uses a VHF carrier to transmit encoded information from the satellite. Data on 112 items are provided once each minute. This paper discusses the over-all command and telemetry systems and considers the general objectives, system aspects and detailed implementation.

TELEMETRY↗
NASA NTRS1972

Encoding and decoding of color information using two-dimensional spatial filtering.

Spatial frequency encoding is described as it applies to both photographic and television systems. In each case, color separations amplitude modulate spatial frequency carriers. The photographic system separates the carriers in the two-dimensional Fourier transform plane using coherent optics; the television system employs a two-dimensional electrical filter to perform the same separation. These filters are synthesized so that the two-dimensional bandwidths of the television camera are used efficiently. Nonlinear processing techniques are also described to minimize crosstalk between channels.

Schaefer, L. F.↗
NASA NTRS1973

Data-aided carrier tracking loops

The characteristics of a data-aided carrier tracking loop are discussed. The loop signal to noise ratio is improved in a phase-locked loop used for tracking a carrier an angle modulated communications system by a quadrature channel added to the phase locked loop. A d.c. signal derived from the quadrature channel is added to the signal fed back to the voltage controlled oscillator in the otherwise conventional phase-locked loop.

Lindsey, W. C.↗
NASA NTRS1973

Doppler compensation by shifting transmitted object frequency within limits

A system and method are disclosed for position locating, deriving centralized air traffic control data, and communicating via voice and digital signals between a multiplicity of remote aircraft, including supersonic transports, and a central station. Such communication takes place through a synchronous satellite relay station. Side tone ranging patterns, as well as the digital and voice signals, are modulated on a carrier transmitted from the central station and received on all of the supersonic transports. Each aircraft communicates with the ground stations via a different frequency multiplexed spectrum. Supersonic transport position is derived from a computer at the central station and supplied to a local air traffic controller. Position is determined in response to variable phase information imposed on the side tones at the aircrafts. Common to all of the side tone techniques is Doppler compensation for the supersonic transport velocity.

Laughlin, C. R., Jr.↗
NASA NTRS1976

Comparison of bit synchronization schemes using AM and summed clocks

This paper considers bit synchronization through the use of a separate clock signal which is either amplitude modulated onto or summed with the data signal. For continuous data transmission, such schemes are known to be inferior, in the sense of efficient use of power, to schemes which derive synchronization directly from the data signal. However, these techniques have application in burst systems such as spacecraft command systems, and in systems where receiver simplicity is more important than power conservation. For systems in which the composite data-clock signal subsequently modulates an RF carrier, it is shown that the summed clock signal performs slightly better than the AM clock signal, and that for both signal types, the optimum allocation of power between data and clock is approximately 9:1.

Geist, J. M.↗