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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Destination directed packet switch architecture for a geostationary communication satellite network

A major effort at NASA/Lewis is to identify and develop critical digital technologies and components that enable new commercial missions or significantly improve the performance, cost efficiency, and/or reliability of existing and planned space comunications systems. NASA envisions the need for low data rate, direct to the user communications services, for data, facsimile, voice, and video conferencing. A report that focuses on destination directed packet switching architectures for geostationary communication satellites is presented.

Ivancic, W. D.↗
NASA NTRS1993

Destination-directed, packet-switched architecture for a geostationary communications satellite network

A major goal of the Digital Systems Technology Branch at the NASA Lewis Research Center is to identify and develop critical digital components and technologies that either enable new commercial missions or significantly enhance the performance, cost efficiency, and/or reliability of existing and planned space communications systems. NASA envisions a need for low-data-rate, interactive, direct-to-the-user communications services for data, voice, facsimile, and video conferencing. The network would provide enhanced very-small-aperture terminal (VSAT) communications services and be capable of handling data rates of 64 kbps through 2.048 Mbps in 64-kbps increments. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints. The focus of current space segment developments is a flexible, high-throughput, fault-tolerant onboard information-switching processor (ISP) for a geostationary satellite communications network. The Digital Systems Technology Branch is investigating both circuit and packet architectures for the ISP. Destination-directed, packet-switched architectures for geostationary communications satellites are addressed.

Ivancic, William D.↗
NASA NTRS1994

Advanced technology for a satellite multichannel demultiplexer/demodulator

Satellite on-board processing is needed to efficiently service multiple users while at the same time minimizing earth station complexity. The processing satellite receives a wideband uplink at 30 GHz and down-converts it to a suitable intermediate frequency. A multichannel demultiplexer then separates the composite signal into discrete channels. Each channel is then demodulated by bulk demodulators, with the baseband signals routed to the downlink processor for retransmission to the receiving earth stations. This type of processing circumvents many of the difficulties associated with traditional bent-pipe repeater satellites. Uplink signal distortion and interference are not retransmitted on the downlink. Downlink power can be allocated in accordance with user needs, independent of uplink transmissions. This allows the uplink users to employ different data rates as well as different modulation and coding schemes. In addition, all downlink users have a common frequency standard and symbol clock on the satellite, which is useful for network synchronization in time division multiple access schemes. The purpose of this program is to demonstrate the concept of an optically implemented multichannel demultiplexer (MCD). A proof-of-concept (POC) model has been developed which has the ability to receive a 40 MHz wide composite signal consisting of up to 1000 40 kHz QPSK modulated channels and perform the demultiplexing process. In addition a set of special test equipment (STE) has been configured to evaluate the performance of the POC model. The optical MCD is realized as an acousto-optic spectrum analyzer utilizing the capability of Bragg cells to perform the required channelization. These Bragg cells receive an optical input from a laser source and an RF input (the signal). The Bragg interaction causes optical output diffractions at angles proportional to the RF input frequency. These discrete diffractions are optically detected and output to individual demodulators for baseband conversion. Optimization of the MCD design was conducted in order to achieve a compromise between two opposing sources of signal degradation: adjacent channel interference and intersymbol interference. The system was also optimized to allow simple, inexpensive ground stations communications with the MCD. These design goals led to the realization of a POC MCD which demonstrates the demultiplexing function with minimal signal degradation. Performance evaluation results using the STE equipment indicate that the dynamic range of the demultiplexer in the presence of adjacent and multiple channel loading is 40 - 50 dB. Measured bit error rate (BER) probabilities varied from the predicted theoretical results by one dB or less. The performance of the proof-of-concept model indicate that the development of a space qualified optically implemented MCD are feasible. The advantages to such an implementation include reduced size, weight and power and increased reliability when compared with electronic approaches. All of these factors are critical to on-board satellite processors. Further optimization can be conducted which trade ground station complexity and MCD performance to achieve desired system results.

Abramovitz, Irwin J.↗
NASA NTRS1994

Collection development at the NOAA Central Library

The National Oceanic and Atmospheric Administration (NOAA) Central Library collection, approximately one million volumes, incorporates the holdings of its predecessor agencies. Within the library, the collections are filed separately, based on their source and/or classification schemes. The NOAA Central Library provides a variety of services to users, ranging from quick reference and interlibrary loan to in-depth research and online data bases.

Quillen, Steve R.↗
NASA NTRS1999

Gulf of Mexico Helicopter Offshore System Technologies Recommended Development Path

The National Aeronautics and Space Administration (NASA) Advanced Air Transportation Technologies (AATT) project in cooperation with the Department of Transportation (DOT) Volpe National Transportation Systems Center (VNTSC) contracted with the System Resources Corporation (SRC) for the evaluation of the existing environment and the identification of user and service provider needs in the Gulf of Mexico low-altitude Offshore Sector. The results of this contractor activity are reported in the Gulf of Mexico Helicopter Offshore System Technologies Engineering Needs Assessment. A recommended system design and transition strategy was then developed to satisfy the identified needs within the constraints of the environment. This work, also performed under contract to NASA, is the subject of this report.

Koenke, Edmund J.↗
NASA NTRS1998

Development and Preliminary Results of CTAS on Airline Operational Control Center Operations

Continued growth and expansion of air traffic and increased air carrier economic pressures have mandated greater flexibility and collaboration in air traffic management. The ability of airspace users to select their own routes, so called "free-flight", and to more actively manage their fleet operations for maximum economic advantage are receiving great attention. A first step toward greater airspace user and service provider collaboration is information sharing. In this work, arrival scheduling and airspace management data generated by the NASA/FAA Center/TRACON Automation System (CTAS) and used by the FAA service provider is shared with an airline with extensive operations within the CTAS operational domain. The design and development of a specialized airline CTAS "repeater" system is described, as well as some preliminary results of the impact and benefits of this information on the air carrier's operations. FAA controller per aircraft scheduling information, such as that provided by CTAS, has never before been shared in real-time with an airline. Expected airline benefits include improved fleet planning and arrival gate management, more informed "hold-go" decisions, and avoidance of costly aircraft diversions to alternate airports when faced with uncertain airborne arrival delays.

Zelenka, Richard↗
NASA NTRS2004

Development and Preliminary Results of CTAS on Airline Operational Control Center Operations

Continued growth and expansion of air traffic and increased air carrier economic pressures have mandated greater flexibility and collaboration in air traffic management. The ability of airspace users to select their own routes, so called "free-flight", and to more actively manage their fleet operations for maximum economic advantage are receiving great attention. A first step toward greater airspace user and service provider collaboration is information sharing. In this work, arrival scheduling and airspace management data generated by the NASA/FAA Center/TRACON Automation System (CTAS) and used by the FAA service provider is shared with an airline with extensive operations within the CTAS operational domain. The design and development of a specialized airline CTAS "repeater" system is described, as well as some preliminary results of the impact and benefits of this information on the air carrier's operations. FAA controller per aircraft scheduling information, such as that provided by CTAS, has never before been shared in real-time with an airline. Expected airline benefits include improved fleet planning and arrival gate management, more informed "hold-go decisions, and avoidance of costly aircraft diversions to alternate airports when faced with uncertain airborne arrival delays.

Zelenka, Richard↗
NASA NTRS2005

Expanding the Use of Time-Based Metering: Multi-Center Traffic Management Advisor

Time-based metering is an efficient air traffic management alternative to the more common practice of distance-based metering (or "miles-in-trail spacing"). Despite having demonstrated significant operational benefit to airspace users and service providers, time-based metering is used in the United States for arrivals to just nine airports and is not used at all for non-arrival traffic flows. The Multi-Center Traffic Management Advisor promises to bring time-based metering into the mainstream of air traffic management techniques. Not constrained to operate solely on arrival traffic, Multi-Center Traffic Management Advisor is flexible enough to work in highly congested or heavily partitioned airspace for any and all traffic flows in a region. This broader and more general application of time-based metering is expected to bring the operational benefits of time-based metering to a much wider pool of beneficiaries than is possible with existing technology. It also promises to facilitate more collaborative traffic management on a regional basis. This paper focuses on the operational concept of the Multi-Center Traffic Management Advisor, touching also on its system architecture, field test results, and prospects for near-term deployment to the United States National Airspace System.

Landry, Steven J.↗
NASA NTRS2006

CCSDS Time-Critical Onboard Networking Service

The Consultative Committee for Space Data Systems (CCSDS) is developing recommendations for communication services onboard spacecraft. Today many different communication buses are used on spacecraft requiring software with the same basic functionality to be rewritten for each type of bus. This impacts on the application software resulting in custom software for almost every new mission. The Spacecraft Onboard Interface Services (SOIS) working group aims to provide a consistent interface to various onboard buses and sub-networks, enabling a common interface to the application software. The eventual goal is reusable software that can be easily ported to new missions and run on a range of onboard buses without substantial modification. The system engineer will then be able to select a bus based on its performance, power, etc and be confident that a particular choice of bus will not place excessive demands on software development. This paper describes the SOIS Intra-Networking Service which is designed to enable data transfer and multiplexing of a variety of internetworking protocols with a range of quality of service support, over underlying heterogeneous data links. The Intra-network service interface provides users with a common Quality of Service interface when transporting data across a variety of underlying data links. Supported Quality of Service (QoS) elements include: Priority, Resource Reservation and Retry/Redundancy. These three QoS elements combine and map into four TCONS services for onboard data communications: Best Effort, Assured, Reserved, and Guaranteed. Data to be transported is passed to the Intra-network service with a requested QoS. The requested QoS includes the type of service, priority and where appropriate, a channel identifier. The data is de-multiplexed, prioritized, and the required resources for transport are allocated. The data is then passed to the appropriate data link for transfer across the bus. The SOIS supported data links may inherently provide the quality of service support requested by the intra-network layer. In the case where the data link does not have the required level of support, the missing functionality is added by SOIS. As a result of this architecture, re-usable software applications can be designed and used across missions thereby promoting common mission operations. In addition, the protocol multiplexing function enables the blending of multiple onboard networks. This paper starts by giving an overview of the SOIS architecture in section 11, illustrating where the TCONS services fit into the overall architecture. It then describes the quality of service approach adopted, in section III. The prototyping efforts that have been going on are introduced in section JY. Finally, in section V the current status of the CCSDS recommendations is summarized.

Parkes, Steve↗
NASA NTRS1994

Using the Global GPS Network and Other Satellite Data to Monitor Ionospheric Total Electron Content

A globally distributed network of dual-frequency global positioning system (GPS) receivers is the primary source of data used to measure ionospheric total electron content (TEC) on global scales. Maps of TEC useful for calibrating propagation delays, or monitoring the solar-terrestrial environment, can be produced using this continuously operating network. The maps can also form the basis of a TEC calibration service for users around the world. Potential users may include single-frequency satellite altimetry missions, satellite tracking stations, and astronomical observatories.

satellite altimetry↗
NASA NTRS1978

Mobile Phone Terminal

In the photo, an employee of a real estate firm is contacting his office by means of HICOM, an advanced central terminal for mobile telephones. Developed by the Orlando Division of Martin Marietta Aerospace, Orlando, Florida, and manufactured by Harris Corporation's RF Division, Rochester, N.Y., HICOM upgrades service to users, provides better system management to telephone companies, and makes more efficient use of available mobile telephone channels through a computerized central control terminal. The real estate man, for example, was able to dial his office and he could also have direct-dialed a long distance number. Mobile phones in most areas not yet served by HICOM require an operator's assistance for both local and long distance calls. HICOM improves system management by automatically recording information on all calls for accurate billing, running continual performance checks on its own operation, and reporting any malfunctions to a central office.

Source record↗
NASA NTRS2008

National Aeronautics and Space Administration's (NASA) Third-Generation Tracking and Data Relay Satellites (TDRS)

NASA has contracted with Boeing to provide two third-generation Tracking and Data Relay Satellites (TDRS) designated TDRS K and L, with an option to provide two additional satellites designated TDRS M and N. These TDRS will be used to continue and enhance the user support services of the existing first- and second-generation TDRS spacecraft. The existing TDRS, in conjunction with the TDRS Ground Terminals at the White Sands NM Complex (WSC) and Guam, constitute the Tracking and Data Relay Satellite System (TDRSS). The TDRSS, with other supporting elements, is referred to as the Space Network (SN). The launch of the TDRS K is projected for 2012 with TDRS L planned to follow in 2013. The contract also provides for the modifications to the TDRS Ground Terminals at the WSC required for operation of the new TDRS. This paper provides an overview of the customer services provided by the existing and new TDRS. In addition, planned future customer services such as Bandwidth Efficient Modulation (BEM) and new coding schemes are briefly discussed.

Berndt, Allen K.↗
NASA NTRS2010

Injecting Errors for Testing Built-In Test Software

Two algorithms have been conceived to enable automated, thorough testing of Built-in test (BIT) software. The first algorithm applies to BIT routines that define pass/fail criteria based on values of data read from such hardware devices as memories, input ports, or registers. This algorithm simulates effects of errors in a device under test by (1) intercepting data from the device and (2) performing AND operations between the data and the data mask specific to the device. This operation yields values not expected by the BIT routine. This algorithm entails very small, permanent instrumentation of the software under test (SUT) for performing the AND operations. The second algorithm applies to BIT programs that provide services to users application programs via commands or callable interfaces and requires a capability for test-driver software to read and write the memory used in execution of the SUT. This algorithm identifies all SUT code execution addresses where errors are to be injected, then temporarily replaces the code at those addresses with small test code sequences to inject latent severe errors, then determines whether, as desired, the SUT detects the errors and recovers

Gender, Thomas K.↗
NASA NTRS2012

Performance Analysis of a NASA Integrated Network Array

The Space Communications and Navigation (SCaN) Program is planning to integrate its individual networks into a unified network which will function as a single entity to provide services to user missions. This integrated network architecture is expected to provide SCaN customers with the capabilities to seamlessly use any of the available SCaN assets to support their missions to efficiently meet the collective needs of Agency missions. One potential optimal application of these assets, based on this envisioned architecture, is that of arraying across existing networks to significantly enhance data rates and/or link availabilities. As such, this document provides an analysis of the transmit and receive performance of a proposed SCaN inter-network antenna array. From the study, it is determined that a fully integrated internetwork array does not provide any significant advantage over an intra-network array, one in which the assets of an individual network are arrayed for enhanced performance. Therefore, it is the recommendation of this study that NASA proceed with an arraying concept, with a fundamental focus on a network-centric arraying.

Nessel, James A.↗
NASA NTRS2012

NASA Integrated Space Communications Network

The NASA Integrated Network for Space Communications and Navigation (SCaN) has been in the definition phase since 2010. It is intended to integrate NASA s three existing network elements, i.e., the Space Network, Near Earth Network, and Deep Space Network, into a single network. In addition to the technical merits, the primary purpose of the Integrated Network is to achieve a level of operating cost efficiency significantly higher than it is today. Salient features of the Integrated Network include (a) a central system element that performs service management functions and user mission interfaces for service requests; (b) a set of common service execution equipment deployed at the all stations that provides return, forward, and radiometric data processing and delivery capabilities; (c) the network monitor and control operations for the entire integrated network are conducted remotely and centrally at a prime-shift site and rotating among three sites globally (a follow-the-sun approach); (d) the common network monitor and control software deployed at all three network elements that supports the follow-the-sun operations.

Tai, Wallace↗
NASA NTRS2016

Preliminary Assessment of Operational Hazards and Safety Requirements for Airborne Trajectory Management (ABTM) Roadmap Applications

A set of five developmental steps building from the NASA TASAR (Traffic Aware Strategic Aircrew Requests) concept are described, each providing incrementally more efficiency and capacity benefits to airspace system users and service providers, culminating in a Full Airborne Trajectory Management capability. For each of these steps, the incremental Operational Hazards and Safety Requirements are identified for later use in future formal safety assessments intended to lead to certification and operational approval of the equipment and the associated procedures. Two established safety assessment methodologies that are compliant with the FAA's Safety Management System were used leading to Failure Effects Classifications (FEC) for each of the steps. The most likely FEC for the first three steps, Basic TASAR, Digital TASAR, and 4D TASAR, is "No effect". For step four, Strategic Airborne Trajectory Management, the likely FEC is "Minor". For Full Airborne Trajectory Management (Step 5), the most likely FEC is "Major".

Cotton, William B.↗
NASA NTRS2016

TDRSS Augmentation System for Satellites

In 2015, NASA Goddard Space Flight Center (GSFC) reinvigorated the development of the TDRSS Augmentation Service for Satellites (TASS). TASS is a global, space-based, communications and navigation service for users of Global Navigation Satellite Systems(GNSS) and the Tracking and Data Relay Satellite System (TDRSS). TASS leverages the existing TDRSS to provide an S-band beacon radio navigation and messaging source to users at orbital altitudes 1400 km and below.

TDRS↗