SEARCH · Search NASA

Results for “ACTS”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9

All sources NASA NTRS DOE OSTI

NASA NTRS1986

ACTS baseband processing

The baseband processor designed for NASA's ACTS experimental system operating in Ka band is described. The ACTS baseband processor facilitates the interconnection necessary to support scanning spot beam low bit rate communications. The dynamic reconfiguration of message routing and the individual application of forward correction coding to overcome localized rain fading are among the processors many advantages. Preliminary hardware testing results are reviewed.

Moat, Richard L.↗

NASA NTRS1988

ACTS - The first step toward a switchboard in the sky

The Advanced Communications Technology Satellite (ACTS), now under development and scheduled for launch in May 1992, is presently the main focus of NASA's communications program. Key technologies for ACTS include electronically hopping spot beam antennas, on-board processing and circuit switching, and Ka-band transmission.

Naderi, F. Michael↗

NASA NTRS1988

A laser communication experiment utilizing the ACT satellite and an airborne laser transceiver

The Advanced Communications Technology Satellite (ACTS) will carry a laser communications transmitter package in order to attempt the experimental reception of signals transmitted from earth orbit. The ACTS laser package includes both a heterodyne transmitter and a direct-detection transmitter. The laser receiver will be installed in an aircraft that is fitted with the requisite signal window. The anticipated capability of this signal detector is noted.

Provencher, C.↗

NASA NTRS1989

ACTS propagation concerns, issues, and plans

ACTS counters fading by resource sharing between the users. It provides a large margin only for those terminals which are at risk by unfavorable atmospheric conditions. ACTS, as an experimental satellite, provides a 5 dB clear weather margin and 10 dB additional margin via rate reduction and encoding. For the uplink, this margin may be increased by exercising uplink power control. Some of the challenges faced by the radiowave propagation community are listed. The issue of needs for the satellite are listed, both general and specific.

Davarian, Faramaz↗

NASA NTRS1990

The Advanced Communications Technology Satellite (ACTS) capabilities for serving science

Results of research on potential science applications of the NASA Advanced Communications Technology Satellite (ACTS) are presented. Discussed here are: (1) general research on communications related issues; (2) a survey of science-related activities and programs in the local area; (3) interviews of selected scientists and associated telecommunications support personnel whose projects have communications requirements; (4) analysis of linkages between ACTS functionality and science user communications activities and modes of operation; and (5) an analysis of survey results and the projection of conclusions to a national scale.

Meyer, Thomas R.↗

NASA NTRS1990

ACTS Hardware - A Pictorial

The salient features of the Advanced Communiations Technology Satellite (ACTS) that is being presently developed under NASA sponsorship and is now in the stage of flight hardware assembly and integration, are described. Particular attention is given to the hardware components of the spacecraft, the engineering model communication package, and special test equipment. The ACTS is being prepared for a launch in May of 1992.

Gargione, Frank↗

NASA NTRS1990

ACTS Propagation Program

The ACTS Propagation Program, initiated to develop the propagation effects data for use in the design of future satellite systems, is described. The initial phase of the program uses the ESA's Olympus satellite to provide measurements of the fade slope, depth, and duration of propagation. The results will be applied to develop power control algorithms in time for the ACTS launch in 1992. The plan calls for the development of about 10 propagation terminals, with each terminal consisting of a two-channel receiver, a two-channel radiometer, and a data-acquisition system, which will be loaned to different research centers and universities for data collection and analysis.

Davarian, Faramaz↗

NASA NTRS1990

Experiments for Ka-band mobile applications: The ACTS mobile terminal

To explore the potential of Ka-band to support mobile satellite services, the Jet Propulsion Laboratory (JPL) has initiated the design and development of a Ka-band land-mobile terminal to be used with the Advanced Communications Technology Satellite (ACTS). The planned experimental setup with ACTS is described. Brief functional descriptions of the mobile and fixed terminals are provided. The inputs required from the propagation community to support the design activities and the planned experiments are also discussed.

Estabrook, Polly↗

NASA NTRS1991

A charging study of ACTS using NASCAP

The NASA Charging Analyzer Program (NASCAP) computer code is a three dimensional finite element charging code designed to analyze spacecraft charging in the magnetosphere. Because of the characteristics of this problem, NASCAP can use an quasi-static approach to provide a spacecraft designer with an understanding of how a specific spacecraft will interact with a geomagnetic substorm. The results of the simulation can help designers evaluate the probability and location of arc discharges of charged surfaces on the spacecraft. A charging study of NASA's Advanced Communication Technology Satellite (ACTS) using NASCAP is reported. The results show that the ACTS metalized multilayer insulating blanket design should provide good electrostatic discharge control.

Herr, Joel L.↗

NASA NTRS1991

Control of nausea and autonomic dysfunction with terfenadine, a peripherally acting antihistamine

Terfenadine (Seldane) was admisistered to 14 male subjects in a randomized, double-blinded, and cross-over design to assess the efficacy of this peripherally active antihistamine as an antimotion sickness drug. Terfenadine possesses practically no central side effects. A staircase profile test was administered 4 h following placebo or a single oral dose of terfenadine (300 mg). The study revealed a statistically significant therapeutic effect from terfenadine (p less than 0.05). This led to a conclusion that, because the drug does not or only poorly crosses the blood-brain barrier, a selective peripheral antihistamine action may be sufficient in the control of motion sickness induced through cross-coupled accelerative semicircular canal stimulation using a rotating chair. This finding implies that other peripherally acting agents might be found that possess even greater antimotion sickness efficacy. The present research raises additional questions regarding current theories on the etiology of motion sickness, its associated autonomic system dysfunction, and the validity of assumptions that effective pharmacological agents must act centrally.

Kohl, Randall L.↗

NASA NTRS1992

Advanced Communication Technology Satellite (ACTS) multibeam antenna analysis and experiment

One of the most important aspects of a satellite communication system design is the accurate estimation of antenna performance degradation. Pointing error, end coverage gain, peak gain degradation, etc. are the main concerns. The thermal or dynamic distortions of a reflector antenna structural system can affect the far-field antenna power distribution in a least four ways. (1) The antenna gain is reduced; (2) the main lobe of the antenna can be mispointed thus shifting the destination of the delivered power away from the desired locations; (3) the main lobe of the antenna pattern can be broadened, thus spreading the RF power over a larger area than desired; and (4) the antenna pattern sidelobes can increase, thus increasing the chances of interference among adjacent beams of multiple beam antenna system or with antenna beams of other satellites. The in-house developed NASA Lewis Research Center thermal/structural/RF analysis program was designed to accurately simulate the ACTS in-orbit thermal environment and predict the RF antenna performance. The program combines well establish computer programs (TRASYS, SINDA and NASTAN) with a dual reflector-physical optics RF analysis program. The ACTS multibeam antenna configuration is analyzed and several thermal cases are presented and compared with measurements (pre-flight).

Acosta, Roberto J.↗

NASA NTRS1991

Commercial applications of the ACTS mobile terminal millimeter-wave antennas

NASA's Jet Propulsion Laboratory is currently developing the Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT), which will provide voice, data, and video communications to and from a vehicle (van, truck, or car) via NASA's geostationary ACTS satellite using the K- and K(sub a)-band frequency bands. The AMT is already planned to demonstrate a variety of communications from within the mobile vehicular environment, and within this paper a summary of foreseen commercial application opportunities is given. A critical component of the AMT is its antenna system, which must establish and maintain the basic RF link with the satellite. Two versions of the antenna are under development, each incorporating different technologies and offering different commercial applications.

Densmore, Arthur C.↗

NASA NTRS1991

Advanced Communications Technology Satellite (ACTS)

The NASA Advanced Communications Technology Satellite (ACTS) provides high risk technologies having the potential to dramatically enhance the capabilities of the satellite communications industry. This experimental satellite, which will be launched by NASA in 1993, will furnish the technology necessary for providing a range of services. Utilizing the ACTS very-high-gain-hopping spot-beam antennas with on-board routing and processing, Very Small Aperture Terminal (VSAT) digital networks which provide on-demand, full-mesh-convectivity 1.544-MBPS services with only a single hop can be established. The high-gain spot-beam antenna at Ka-band permits wide area, flexible networks providing high data rate services between modest-size earth terminals.

Plecity, Mark S.↗

NASA NTRS1992

The Olympus and ACTS propagation measurement campaigns in the U.S

The Jet Propulsion Laboratory under the auspices of NASA carries out radiowave propagation studies for satellite communications. As a prelude to the ACTS experiments, it was considered prudent to gather experience in 20/30 GHz propagation using the Olympus satellite beacons at 12, 20, and 30 GHz. Therefore, NASA funded an experiment program with Virginia Tech under JPL management to develop hardware and to collect data for the Olympus campaign. The paper reviews the results of the Olympus campaign. The experience gathered from this campaign is beneficial to the forthcoming ACTS propagation program which is also discussed in this paper.

Stutzman, Warren L.↗

NASA NTRS1989

Advanced Communications Technology Satellite (ACTS)

The NASA Advanced Communications Technology Satellite (ACTS) was conceived to help maintain U.S. leadership in the world's communications-satellite market. This experimental satellite is expected to be launched by NASA in 1992 and to furnish the technology necessary for establishing very small aperture terminal digital networks which provide on-demand full-mesh connectivity, and 1.544-MBPS services with only a single hop. Utilizing on-board switching and processing, each individual voice or data circuit can be separately routed to any location in the network. This paper provides an overview of the ACTS and discusses the value of the technology for future communications systems.

Gedney, Richard T.↗

NASA NTRS1992

The ACTS propagation program

The success or failure of the ACTS experiment will depend on how accurately the rain-fade statistics and fade dynamics can be predicted in order to derive an appropriate algorithm that will combat weather vagaries, specifically for links with small terminals, such as very small aperture terminals (VSAT's) where the power margin is a premium. The planning process and hardware development program that will comply with the recommendations of the ACTS propagation study groups are described.

Chakraborty, D.↗

NASA NTRS1991

The revitalization of health and education in Rural America Act of 1992

During the preceding decade of the 1980's, rural communities witnessed an exodus of over 5 million residents to urban and suburban areas of the nation. It has become increasingly clear that rural parts of the country must adopt aggressive strategies to strengthen rural communities and enhance the quality of life for its citizens into the 21st century. Studies by the U.S. Department of Commerce, Office of Technology Assessment, and the Aspen Institute all identify advanced telecommunications systems as the linchpin for a vigorous future for rural America. The Revitalization of Health and Education in Rural America Act of 1992 incorporates these recommendations into viable strategies to improve health care and educational services for rural citizens. By linking up hospitals and schools through advanced telecommunications technology, vast geographic distances are instantly reduced. With the proper infrastructure in place, up-to-date telecommunications services will facilitate endless opportunities for improving the quality of life in remote areas. This comprehensive legislation is the critical first step in forging a partnership with urban communities to create an economically sound and technologically advanced America for generations to come. Improvement of health care and educational services in rural areas through the implementation of interactive telecommunications systems is addressed. A copy of the Act is included.

English, Glenn↗

NASA NTRS1993

The ACTS propagation terminal delivery and support

Viewgraphs on the Advanced Communications Technology Satellite (ACTS) propagation terminal delivery and support are included. Topics covered include: the ACTS propagation terminal (APT) development program; terminal overview; physical units; test results; status of terminals and schedule; shipping cartons; and site support.

Stutzman, Warren L.↗