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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Phased-Array Satcom Antennas Developed for Aeronautical Applications

The Advanced Communications (AC) for Aeronautics research at the NASA Glenn Research Center integrates both aeronautics and space communications technologies to achieve the national objective of upgrading the present National Airspace System infrastructure by responding to the agency's aviation capacity and safety goals. One concept for future air traffic management, free flight, presents a significantly increased demand for communications systems capacity and performance in comparison to current air traffic management practices. Current aeronautical communications systems are incapable of supporting the anticipated demands, and the new digital data communications links that are being developed, or are in the early stages of implementation, are not primarily designed to carry the data-intensive free flight air traffic management (ATM) communications loads. Emerging satellite communications technologies are the best potential long-term solution to provide the capacity and performance necessary to enable a mature free flight concept to be deployed. NASA AC/ATM funded the development of a Boeing-designed Ku-band transmit phased-array antenna, a combined in-house and contract effort. Glenn designed and integrated an Aeronautical Mobile Satellite Communications terminal based on the transmit phased-array antenna and a companion receive phased-array antenna previously developed by Boeing.

Kerczewski, Robert J.↗
NASA NTRS1997

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 61: The Technical Communications Practices of ESL Aerospace Engineering Students in the United States: Results of a National Survey

When engineering students graduate and enter the world of work, they make the transition from an academic to a professional community of knowledge. The importance of oral and written communication to the professional success and advancement of engineers is well documented. For example, studies such as those conducted by Mailloux (1989) indicate that communicating data, information, and knowledge takes up as much as 80% of an engineer's time. However, these same studies also indicate that many engineering graduates cannot (a) write technical reports that effectively inform and influence decisionmaking, (b) present their ideas persuasively, and (c) communicate with their peers. If these statements are true, how is learning to communicate effectively in their professional knowledge community different for engineering students educated in the United States but who come from other cultures-cultures in which English is not the primary language of communication? Answering this question requires adequate and generalizable data about these students' communications abilities, skills, and competencies. To contribute to the answer, we undertook a national (mail) survey of 1,727 student members of the American Institute of Aeronautics and Astronautics (AIAA). The focus of our analysis and this paper is a comparison of the responses of 297 student members for whom English is a second language with the responses of 1,430 native English speaking students to queries regarding career choice, bilingualism and language fluency, communication skills, collaborative writing, computer use, and the use of electronic (computer) networks.

Webb, John R.↗
NASA NTRS2012

Optical Phase Recovery and Locking in a PPM Laser Communication Link

Free-space optical communication holds great promise for future space missions requiring high data rates. For data communication in deep space, the current architecture employs pulse position modulation (PPM). In this scheme, the light is transmitted and detected as pulses within an array of time slots. While the PPM method is efficient for data transmission, the phase of the laser light is not utilized. The phase coherence of a PPM optical signal has been investigated with the goal of developing a new laser communication and ranging scheme that utilizes optical coherence within the established PPM architecture and photon-counting detection (PCD). Experimental measurements of a PPM modulated optical signal were conducted, and modeling code was developed to generate random PPM signals and simulate spectra via FFT (Fast Fourier Transform) analysis. The experimental results show very good agreement with the simulations and confirm that coherence is preserved despite modulation with high extinction ratios and very low duty cycles. A real-time technique has been developed to recover the phase information through the mixing of a PPM signal with a frequency-shifted local oscillator (LO). This mixed signal is amplified, filtered, and integrated to generate a voltage proportional to the phase of the modulated signal. By choosing an appropriate time constant for integration, one can maintain a phase lock despite long dark times between consecutive pulses with low duty cycle. A proof-of-principle demonstration was first achieved with an RF-based PPM signal and test setup. With the same principle method, an optical carrier within a PPM modulated laser beam could also be tracked and recovered. A reference laser was phase-locked to an independent pulsed laser signal with low-duty-cycle pseudo-random PPM codes. In this way, the drifting carrier frequency in the primary laser source is tracked via its phase change in the mixed beat note, while the corresponding voltage feedback maintains the phase lock between the two laser sources. The novelty and key significance of this work is that the carrier phase information can be harnessed within an optical communication link based on PPM-PCD architecture. This technology development could lead to quantum-limited efficient performance within the communication link itself, as well as enable high-resolution optical tracking capabilities for planetary science and spacecraft navigation.

Aveline, David C.↗
NASA NTRS1981

ADS pilot program Plan

The Applications Data Service (ADS) is a system based on an electronic data communications network which will permit scientists to share the data stored in data bases at universities and at government and private installations. It is designed to allow users to readily locate and access high quality, timely data from multiple sources. The ADS Pilot program objectives and the current plans for accomplishing those objectives are described.

Clauson, J.↗
NASA NTRS1990

Future developments in aeronautical satellite communications

Very shortly aeronautical satellite communications will be introduced on a world wide basis. By the end of the year, voice communications (both to the cabin and cockpit) and packet data communications will be available to both airlines and executive aircraft. During the decade following the introduction of the system, there will be many enhancements and developments which will increase the range of applications, expand the potential number of users, and reduce costs. A number of ways in which the system is expected to evolve over this period are presented. Among the issues which are covered are the impact of spot beam satellites, spectrum and power conservation techniques, and the expanding range of user services.

Wood, Peter↗
NASA NTRS1993

The FAA satellite communications program

The Federal Aviation Administration is developing satellite communications capabilities to enhance air traffic services, first in oceanic and remote regions, and later for United States domestic services. The program includes four projects which develop technical standards, assure adequate system performance, support implementation, and provide for research and development for selected areas of U.S. domestic satellite communications. The continuing focus is the application of automated data communications, which is already permitting enhanced and regular position reporting. Voice developments, necessary for non-routine communications, are also included among the necessary activities to improve ATC communications.

Burcham, Karen L.↗
NASA NTRS2005

TAMDAR Sensor Validation in 2003 AIRS II

This study entails an assessment of TAMDAR in situ temperature, relative humidity and winds sensor data from seven flights of the UND Citation II. These data are undergoing rigorous assessment to determine their viability to significantly augment domestic Meteorological Data Communications Reporting System (MDCRS) and the international Aircraft Meteorological Data Reporting (AMDAR) system observational databases to improve the performance of regional and global numerical weather prediction models. NASA Langley Research Center participated in the Second Alliance Icing Research Study from November 17 to December 17, 2003. TAMDAR data taken during this period is compared with validation data from the UND Citation. The data indicate acceptable performance of the TAMDAR sensor when compared to measurements from the UND Citation research instruments.

Daniels, Taumi S.↗
NASA NTRS2003

Introduction to standardized spacecraft onboard interfaces

This paper will provide a description of the SOIF work by describing three orthogonal views: the Services View that describes data communication services, the Interoperability view shows how to exchange data and messages between different spacecraft elements, and the Protocol view, that describes the SOIF protocols and services.

space interfaces avionics interfaces standard inte↗
NASA NTRS2003

Standardized Spacecraft Onboard Interfaces

The Consultative Committee for Space Data Systems (CCSDS), an international organization of national space agencies, is branching out to provide new standards to enhanced reuse of onboard spacecraft equipment and software. These Spacecraft Onboard Interface (SOIF) standards will be, in part, based on the well-known Internet protocols. This paper will provide a description of the SOIF work by describing three orthogonal views: the Services View that describes data communications services, the Interoperability view shows how to exchange data and messages between different spacecraft elements, and the Protocol view, that describes the SOIF protocols and services. We will also provide a description of the present state of the services that will be provided to SOIF users, and are the basis of the utility of these standards.

space interfaces↗
NASA NTRS2007

Switched Band-Pass Filters for Adaptive Transceivers

Switched band-pass filters are key components of proposed adaptive, software- defined radio transceivers that would be parts of envisioned digital-data-communication networks that would enable real-time acquisition and monitoring of data from geographically distributed sensors. Examples of sensors to be connected to such networks include security cameras, radio-frequency identification units, and geolocation units based on the Global Positioning System. Through suitable software configuration and without changing hardware, these transceivers could be made to operate according to any of a number of complex wireless-communication standards that could be characterized by diverse modulation schemes, bandwidths, and data-handling protocols. The adaptive transceivers would include field-programmable gate arrays (FPGAs) and digital signal-processing hardware. In the receiving path of a transceiver, the incoming signal would be amplified by a low-noise amplifier (LNA). The output spectrum of the LNA would be processed by a band-pass filter operating in the frequency range between 900 MHz and 2.4 GHz. Then a down-converter would translate the signal to a lower frequency range to facilitate analog-to-digital conversion, which would be followed by baseband processing by one or more FPGAs. In the transmitting path, a digital stream would first be converted to an analog signal, which would then be up-converted to a selected frequency band before being applied to a transmitting power amplifier. The aforementioned band-pass filter in the receiving path would be a combination of resonant inductor-and-capacitor filters and switched band-pass filters. The overall combination would implement a switch function designed mathematically to exhibit desired frequency responses and to switch the signal in each frequency band to an analog-to-digital converter appropriate for that band to produce a digital intermediate-frequency signal for digital signal processing.

Wang, Ray↗
NASA NTRS2010

High-Intensity Radiated Field Fault-Injection Experiment for a Fault-Tolerant Distributed Communication System

Safety-critical distributed flight control systems require robustness in the presence of faults. In general, these systems consist of a number of input/output (I/O) and computation nodes interacting through a fault-tolerant data communication system. The communication system transfers sensor data and control commands and can handle most faults under typical operating conditions. However, the performance of the closed-loop system can be adversely affected as a result of operating in harsh environments. In particular, High-Intensity Radiated Field (HIRF) environments have the potential to cause random fault manifestations in individual avionic components and to generate simultaneous system-wide communication faults that overwhelm existing fault management mechanisms. This paper presents the design of an experiment conducted at the NASA Langley Research Center's HIRF Laboratory to statistically characterize the faults that a HIRF environment can trigger on a single node of a distributed flight control system.

Yates, Amy M.↗
DOE OSTI2016

Distributing an executable job load file to compute nodes in a parallel computer

Distributing an executable job load file to compute nodes in a parallel computer, the parallel computer comprising a plurality of compute nodes, including: determining, by a compute node in the parallel computer, whether the compute node is participating in a job; determining, by the compute node in the parallel computer, whether a descendant compute node is participating in the job; responsive to determining that the compute node is participating in the job or that the descendant compute node is participating in the job, communicating, by the compute node to a parent compute node, an identification of a data communications link over which the compute node receives data from the parent compute node; constructing a class route for the job, wherein the class route identifies all compute nodes participating in the job; and broadcasting the executable load file for the job along the class route for the job.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Distributing an executable job load file to compute nodes in a parallel computer

Distributing an executable job load file to compute nodes in a parallel computer, the parallel computer comprising a plurality of compute nodes, including: determining, by a compute node in the parallel computer, whether the compute node is participating in a job; determining, by the compute node in the parallel computer, whether a descendant compute node is participating in the job; responsive to determining that the compute node is participating in the job or that the descendant compute node is participating in the job, communicating, by the compute node to a parent compute node, an identification of a data communications link over which the compute node receives data from the parent compute node; constructing a class route for the job, wherein the class route identifies all compute nodes participating in the job; and broadcasting the executable load file for the job along the class route for the job.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1988

Space communication link propagation data for selected cities within the multiple beam and steerable antenna coverage areas of the advanced communications technology satellite

Rain attenuation propagation data for 68 cities within the coverage area of the multiple beam and steerable antennas of the Advanced Communications Technology Satellite (ACTS) are presented. These data provide the necessary data base for purposes of communication link power budgeting and rain attenuation mitigation controller design. These propagation parameters are derived by applying the ACTS Rain Attenuation Prediction Model to these 68 locations. The propagation parameters enumerated in tabular form for each location are as follows: (1) physical description of the link and location (e.g., latitude, longitude, antenna elevation angle, etc.), link availability versus attenuation margin (also in graphical form), fading time across fade depths of 3, 5, 8, and 15 dB versus fade duration, and required fade control response time for controller availabilities of 99.999, 99.99, 99.9, and 99 percent versus sub-threshold attenuation levels. The data for these specific locations can be taken to be representative of regions near these locations.

Manning, Robert M.↗
NASA NTRS1978

Versatile communications terminal

Widely-separated parties are linked into efficient communications network by versatile control terminal. Terminal handles voice and data communications via both telephone lines and radio-frequency channels. It includes telephone-to-radio "patch", telephone autodialer, and other advanced features to provide rapid communications for applications such as emergency medical services (EMS) operations.

Belasco, N.↗
DOE OSTI2019

Final Report for Transmission of Information by Acoustic Communication along Metal Pathways in Nuclear Facilities

Transmission of information using elastic waves on existing metallic pipes provides an alternative communication option for a nuclear facility. The advantages of this approach consist of transmitting information through barriers, such as the containment building wall. A viable candidate for acoustic communication channel is a chemical volume control system (CVCS) stainless steel pipe, which penetrates through the containment building wall. A laboratory bench-scale system consisting of a nuclear grade CVCS-like pipe and ultrasonic transducers was assembled for a preliminary communication system analysis. Because of low bandwidth and spectral dispersion of ultrasonic transducers, on off keying (OOK) protocol was chosen for data communication. Operation of the acoustic communication during normal and post-accident conditions involves data transmission on the CVCS pipe, which according to literature guidelines, will be at 50°C and 150°C, respectively. Preliminary communication system development was performed using paintbrush PZT transducers capable of continuous operation at temperatures up to 80°C. Next, high-temperature LiNbO 3 acoustic transducers, originally developed for flow metering applications of EBRII reactor at Argonne, were utilized to develop a high-temperature acoustic communication system. A Gaussian pulse shape filter was introduced to suppress ringing and thus reduce inter-symbol interference. This resulted in enhancement of data transmission bitrate. Heating tapes, temperature controllers, and thermal insulation were installed on the laboratory pipe to study acoustic communication at elevated temperature. This included development of custom insertion heating elements for controlling temperature at pipe ends. Demonstrations of communication at high temperature included transmission of images and text files. Main achievements thus far include demonstration of transmission of 90KB image at the bitrate of 10Kbps with bit error rate smaller than 10 -3 across the pipe heated to 50°C and 150°C. Final phase of project development involved investigating strategies for deployment of the ultrasonic communication system in a representative environment. Mechanisms Engineering Test Loop (METL) facility at ANL was chosen as a viable candidate for communication system demonstration. Analysis of piping manifolds at METL has shown that in a typical scenario, ultrasonic signals have to be transmitted over straight and bent piping sections. This report describes preliminary studies on transmission of information with ultrasonic shear waves across bent piping sections. A test article consisting of a stainless steel pipe bent at 90° was developed for laboratory analysis of ultrasonic signal transmission. The bent piping test article developed by welding two straight pipes to an elbow. For consistency, the diameter and wall thickness of the bent pipe is the same as that of the straight pipe utilized in prior studies. COMSOL computer simulations were performed to study ultrasonic refracted shear wave coupling and transmission across bent piping. Preliminary evaluations of ultrasonic shear wave transmission were conducted with piezoelectric (PZT) and LiNbO 3 transducers, with the signals recorded with previously developed LabView interface. Preliminary results have shown significant dispersion of transmitted signals, most likely due to reflections and scattering by piping welds. Signal distortion compensation algorithm based on time reversal modulation (TRM) was initially investigated for transmission through solids, and demonstrated for signals transmitted over the bent pipe. Using TRM, it was shown that communication bitrates of 100Kbps were achievable, in principle.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗