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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Communications availability: Estimation studies at AMSC

The results of L-band communications availability work performed to date are presented. Results include a L-band communications availability estimate model and field propagation trials using an INMARSAT-M terminal. American Mobile Satellite Corporation's (AMSC's) primary concern centers on availability of voice communications intelligibility, with secondary concerns for circuit-switched data and fax. The model estimates for representative terrain/vegetation areas are applied to the contiguous U.S. for overall L-band communications availability estimates.

Sigler, C. Edward, Jr.↗
NASA NTRS1986

Communications platform payload definition study, executive summary

Large geostationary communications platforms have been investigated in a number of studies since 1974 as a possible means to more effectively utilize the geostationary orbital arc and electromagnetic spectrum and to reduce overall satellite communications system costs. This NASA Lewis sponsored study addresses the commercial feasibility of various communications platform payload concepts circa 1998. It defines promising payload concepts, estimates recurring costs and identifies critical technologies needed to permit eventual commercialization. Ten communications service aggregation scenarios describing potential groupings of services were developed for a range of conditions. Payload concepts were defined for four of these scenarios: (1) Land Mobile Satellite Service (LMSS), meet 100% of CONUS plus Canada demand with a single platform; (2) Fixed Satellite Service (FSS) (Trunking + Customer Premises Service (CPS), meet 20% of CONUS demands; (3) FSS (Trunking + video distribution), 10 to 13% of CONUS demand; and (4) FSS (20% of demand) + Inter Satellite Links (ISL) + TDRSS/TDAS Data Distribution.

Clopp, H. W.↗
NASA NTRS2004

Common Operating Picture: UAV Security Study

This initial communication security study is a top-level assessment of basic security issues related to the operation of Unmanned Aerial Vehicles (UAVs) in the National Airspace System (NAS). Security considerations will include information relating to the use of International Civil Aviation Organization (ICAO) Aeronautical Telecommunications Network (ATN) protocols and applications identifying their maturity, as well as the use of IPV4 and a version of mobile IPV6. The purpose of this assessment is to provide an initial analysis of the security implications of introducing UAVs into the NAS.

Source record↗
NASA NTRS1975

A Study of Synchronization Techniques for Optical Communication Systems

The study of synchronization techniques and related topics in the design of high data rate, deep space, optical communication systems was reported. Data cover: (1) effects of timing errors in narrow pulsed digital optical systems, (2) accuracy of microwave timing systems operating in low powered optical systems, (3) development of improved tracking systems for the optical channel and determination of their tracking performance, (4) development of usable photodetector mathematical models for application to analysis and performance design in communication receivers, and (5) study application of multi-level block encoding to optical transmission of digital data.

Gagliardi, R. M.↗
NASA NTRS1974

Integrated source and channel encoded digital communication system design study

This study investigated the configuration and integration of a wideband communication system with a Ku-band rendezvous radar system. The goal of the study was to provide as much commonality between the two systems as possible. The antenna design was described with the only change being the requirement for dual polarization (linear for the radar system and circular for the communication system).

Huth, G. K.↗
NASA NTRS2014

A Study of Future Communications Concepts and Technologies for the National Airspace System - Part II

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is investigating current and anticipated wireless communications concepts and technologies that the National Airspace System (NAS) may need in the next 50 years. NASA has awarded three NASA Research Announcements (NAR) studies with the objective to determine the most promising candidate technologies for air-to-air and air-to-ground data exchange and analyze their suitability in a post-NextGen NAS environment. This paper will present progress made in the studies and describe the communications challenges and opportunities that have been identified during the studies' first year.

Communications↗
NASA NTRS2013

A Study of Future Communications Concepts and Technologies for the National Airspace System-Part I

The National Aviation and Space Administration (NASA) Glenn Research Center (GRC) is investigating current and anticipated wireless communications concepts and technologies that the National Airspace System (NAS) may need in the next 50 years. NASA has awarded three NASA Research Announcements (NAR) studies with the objective to determine the most promising candidate technologies for air-to-air and air-to-ground data exchange and analyze their suitability in a post-NextGen NAS environment. This paper will present progress made in the studies and describe the communications challenges and opportunities that have been identified during the studies' first phase.

National Airspace↗
NASA NTRS2019

Radio Frequency and Optical Communication Link Trade Studies Between Earth, Deep Space Gateway and Lunar Surface

Efficient and accurate communication are two of the most important aspects in a communications system. Hence, it was pertinent that radio frequency (RF) and optical link budget analyses were understood inside and out by the two young careerists when performing this study. This report covers RF and optical trade studies performed between Earth, Deep Space Gateway (DSG), Orion, and the Moon’s lunar surface. Using criteria provided by NASA Headquarters, the links were statically driven allowing review of the systems without bandwidth limitations, spectrum allocations, and hardware implementations. This provided the chance to review the efficiency of the links as technology improves throughout the decades. A few select RF links were analyzed using repeaters while select optical links were compared with coded and uncoded modulation schemes. The results from these analyses again prove the tradeoff theories in communications systems.

Booth, Stephanie L.↗
NASA NTRS2014

A Study of Future Communications Concepts and Technologies for the National Airspace System-Part III

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is investigating current and anticipated wireless communications concepts and technologies that the National Airspace System (NAS) may need in the next 50 years. NASA has awarded three NASA Research Announcements (NAR) studies with the objective to determine the most promising candidate technologies for air-to-air and air-to-ground data exchange and analyze their suitability in a post-NextGen NAS environment. This paper will present progress made in the studies and describe the communications challenges and opportunities that have been identified as part of the study. NASA's NextGen Concepts and Technology Development (CTD) Project integrates solutions for a safe, efficient and high-capacity airspace system through joint research efforts and partnerships with other government agencies. The CTD Project is one of two within NASA's Airspace Systems Program and is managed by the NASA Ames Research Center. Research within the CTD Project is in support the 2011 NASA Strategic Plan Sub-Goal 4.1: Develop innovative solutions and advanced technologies, through a balanced research portfolio, to improve current and future air transportation. The focus of CTD is on developing capabilities in traffic flow management, dynamic airspace configuration, separation assurance, super density operations and airport surface operations. Important to its research is the development of human/automation information requirements and decisionmaking guidelines for human-human and human-machine airportal decision-making. Airborne separation, oceanic intrail climb/descent and interval management applications depend on location and intent information of surrounding aircraft. ADS-B has been proposed to provide the information exchange, but other candidates such as satellite-based receivers, broadband or airborne internet, and cellular communications are possible candidate's.

Navigation↗
NASA NTRS1998

Proceedings of the Eleventh Advanced Communications Technology Satellite Propagation Studies Workshop (APSW 11)

The Advanced Communications Technology Satellite Propagation Studies Workshop (APSW) is convened each year to present the results of the Advanced Communications Technology Satellite (ACTS) Ka-band propagation campaign. Representatives from the space community including industry, academia, and government who are interested in radiowave propagation at Ka-band are invited to APSW for discussions and exchange of information. The ACTS Propagation campaign will complete five years of Ka-Band data collection at seven sites in North America by December 31, 1998. Through this effort, NASA is making a major contribution to the effective utilization of this band by providing timely propagation data and models for predicting the performance of Ka-band links between space and ground.

Golshan, Nasser↗
NASA NTRS1997

Presentations of the Ninth Advanced Communications Technology Satellite Propagation Studies Workshop (APSW IX)

The Advanced Communications Technology Satellite Propagation Studies Workshop (APSW) is convened each year to present the results of the ACTS Propagation Campaign. Representatives from the satellite communications (satcom) industry, academia, and government are invited to APSW for discussions and exchange of information. The ACTS Propagation campaign is completing three years of Ka-Band data collection at seven sites in North America. Through this effort, NASA is making a major contribution to growth of satcom services by providing timely propagation data and models for predicting the performance of Ka-Band satellite communications systems.

Golshan, Nasser↗
NASA NTRS1979

The 18 and 30 GHz fixed service communications satellite system study

The use of the 18 and 30 GHz bands for fixed service satellite communications is examined. The cost and performance expected of 18 and 30 GHz hardware is assessed, selected trunking and direct to user concepts are optimized, and the cost of these systems are estimated. The effect of rain attenuation on the technical and economic viability of the system and methods circumventing the problem are discussed. Technology developments are investigated and cost estimates of these developments are presented.

Bronstein, L. M.↗
NASA NTRS1986

NASA 60 GHz intersatellite communication link definition study. Baseline document

The overall system and component concepts for a 60 GHz intersatellite communications link system (ICLS) are described. The ICLS was designed to augment the capabilities of the current Tracking and Data Relay Satellite System (TDRSS), providing a data rate capacity large enough to accommodate the expected rates for user satellites (USAT's) in the post-1995 timeframe. The use of 60 GHz for the anticipated successor to TDRSS, the Tracking and Data Acquisition System (TDAS), was selected because of current technology development that will enable multigigibit data rates. Additionally, the attenuation of the earth's atmosphere at 60 GHz means that there is virtually no possibility of terrestrially generated interference (intentional or accidental) or terrestrially based intercept. The ICLS includes the following functional areas: (1) the ICLS payload package on the GEO TDAS satellite that communicates simultaneously with up to five LEO USAT's; (2) the payload package on the USAT that communicates with the TDAS satellite; and (3) the crosslink payload package on the TDAS satellite that communicates with another TDAS satellite. Two methods of data relay on-board the TDAS spacecraft were addressed. One is a complete baseband system (demod and remod) with a bi-directional 2 Gbps data stream; the other is a channelized system wherein some of the channels are baseband and others are merely frequency translated before re-transmission. Descriptions of the TDAS antenna, transmitter, receiver, and mechanical designs are presented.

Source record↗
NASA NTRS1977

Integrated source and channel encoded digital communication system design study

The analysis of the forward link signal structure for the shuttle orbiter Ku-band communication system was carried out, based on the assumptions of a 3.03 Mcps PN code. It is shown that acquisition requirements for the forward link can be met at the acquisition threshold C/N0 sub 0 value of about 60 dB-Hz, which corresponds to a bit error rate (BER) of about 0.001. It is also shown that the tracking threshold for the forward link is at about 57 dB-Hz. The analysis of the bent pipe concept for the orbiter was carried out, along with the comparative analysis of the empirical data. The complexity of the analytical approach warrants further investigation to reconcile the empirical and theoretical results. Techniques for incorporating a text and graphics capability into the forward link data stream are considered and a baseline configuration is described.

Udalov, S.↗
NASA NTRS1979

The 18 and 30 GHz fixed service communication satellite system study: Executive summary

The use of the 18 and 30 GHz bands for fixed service satellite communications is examined. Primary objectives were to determine if satellite communication systems using this allocation (27.5 to 30.0 GHz uplink; 17.7 to 20.2 GHz downlink) can be cost competitive with alternate means of communication, and to determine what technological developments would be required to make these systems competitive. To meet these objectives, the cost and performance to be expected of 18 and 30 GHz hardware in the 1985 to 1990 era was assessed, selected trunking and direct to user concepts were optimized, and the cost of these systems was estimated. Finally, the technology developments required to make the most promising of the concepts competitive were identified.

Bronstein, L. M.↗