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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

(abstract) AMT Experiment Results

The Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) experiments have provided a terminal technology testbed for the evaluation of K- and Ka-band mobile satellite communications (satcom). Such a system could prove to be highly beneficial for many different commercial and government mobile satcom users. Combining ACTS' highly concentrated spotbeams with the smaller, higher-gain Ka-band antenna technology results in a system design that can support a much higher throughput capacity than today's commercial configurations. Baseline AMT performance results will be presented. In addition, observations on many of the application-specific experiments will also be provided.

communications↗
NASA NTRS2017

Omnidirectional Inter-Satellite Optical Communicator (ISOC)

The objective of the Omnidirectional Inter-Satellite Optical Communicator (ISOC) project is to design a compact, lightweight,and energy efficient communicator module for use between satellites in space. This module will achieve continuous optical communication, with simultaneous data transmission and reception, at up to1 gigabit per second (Gbits) data rates for small spacecraft separated by up to 200 kilometers (kms). To achieve this goal,a data communicator with full spherical coverage field of view (FOV) needs to be designed. The proposed ISOC is a dodecahedron geometric array of chipscale, microelectromechanical systems (MEMS) based gimbal-less scanning mirrors that provide adjustable beam pointing and spherical FOV coverage for uninterrupted data transmission between several small spacecraft at arbitrary relative positions. This design eliminates known pointing issues and hence allows accurate direction of arrival calculations.Moreover, the proposed approach will enable data relaying between multiple satellites, and enable relative navigation control.

Inter-small satellite communication↗
NASA NTRS1968

20/20 space communications.

Satellite use for two way communication and tracking relays from ground to manned orbiting spacecraft

Hamilton, M.↗
NASA NTRS1995

Propagation experiment of COMETS Ka/Q-band communication link for future satellite cellular system

Mobile/Personal Satellite Communication Systems in L/S-bands are going into the operational phase. In the future, they will be operated in much higher frequency bands, for example in Ka-band, because the available bandwidth in L-band is limited. Systems with large on-board antennas in higher frequencies allow the same configuration as terrestrial cellular radio systems, since the on-board antennas will have many small spot beams. This may be true especially in a low earth orbit system such as Teledesic, which will use Ka-band. The most important parameter of Satellite Cellular may be cell size, that is, a diameter of the spot beam. A system designer needs the local correlation data in a cell and the size of the correlative area. On the other hand, the most significant difficulty of Ka and higher band systems is the countermeasure to rain attenuation. Many-cell systems can manage the limited power of on-board transponders by controlling output power of each beam depending on the rain attenuation of each cell. If the cell size is equal to the correlative area, the system can probably achieve the maximum performance. Propagation data of Ka and higher band obtained in the past shows a long term cumulative feature and link availability, but do not indicate the correlative area. The Japanese COMETS satellite, which will be launched in February 1997, has transponders in Ka and Q-band. The CRL is planning to measure the correlative area using 21 GHz and 44 GHz CW transmissions from the COMETS.

Hase, Yoshihiro↗
NASA NTRS1962

TELSTAR PROJECT

Telstar is the project of the American Telephone and Telegraph Company to demonstrate the relaying of transoceanic telephone service and live television via satellites. It is really much more than that. It will be a calibration of the space environment. We expect that it will tell us a great deal about how to achieve long-life reliable operations in space. This information should be of value to the designers of other kinds of satellites as well as communication satellites. Most of all, we hope that through our cooperative efforts with NASA the Telstar experiment will be a significant step towards the creation of a commercially operable satellite communication system.

Communications satellite↗
NASA NTRS1965

Radome facility Final report

Radome facility for determining microwave reflection coefficients and transmission characteristics of various passive communication satellite materials

PASSIVE SATELLITE↗
NASA NTRS1980

A digitally implemented communications experiment utilizing the communications technology satellite, Hermes

Developments which will reduce the costs associated with the distribution of satellite services are considered with emphasis on digital communication link implementation. A digitally implemented communications experiment (DICE) which demonstrates the flexibility and efficiency of digital transmission of television video and audio, telephone voice, and high-bit-rate data is described. The utilization of the DICE system in a full duplex teleconferencing mode is addressed. Demonstration teleconferencing results obtained during the conduct of two sessions of the 7th AIAA Communication Satellite Systems Conference are discussed. Finally, the results of link characterization tests conducted to determine (1) relationships between the Hermes channel 1 EIRP and DICE model performance and (2) channel spacing criteria for acceptable multichannel operation, are presented.

Jackson, H. D.↗
NASA NTRS1994

K/Ka-band Antenna for Broadband Aeronautical Mobile Application

The Jet Propulsion Laboratory (JPL) has recently begun the development of a Broadband Aeronauical Terminal (BAT) for duplex video satellite communications on commercial or business class aircraft. The BAT is designed for use with NASA's K/Ka-band Advanced Communications Technology Satellite (ACTS).

Broadband Aeronautica Terminal (BAT) aircraft ante↗
NASA NTRS1993

Channel and Terminal Description of the ACTS Mobile Terminal

The Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) is a proof-of-concept K/Ka-band mobile satellite communications terminal under development by NASA at the Jet Propulsion Laboratory. Currently, the AMT is undergoing system integration and test in preparation for a July 1993 ACTS launch and the subsequent commencement of mobile experiments in the fall of 1993. The AMT objectives are presented, followed by a discussion of the AMT communications channel, and mobile terminal design and performance.

communications↗
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 NTRS1977

Public service satellites

The development of the communications satellite system is discussed, taking into account a suggestion by Clarke in 1945 concerning the significance of geosynchronous satellites, the establishment of Intelsat, reductions in the cost of transatlantic telephone calls as a result of satellite communications service, questions of satellite cost, and the need for larger satellites. It is pointed out that the use of the Space Shuttle will reduce the cost of placing a satellite in orbit from more than half to less than a quarter of the total cost of design, construction, and launch. Attention is given to studies of a personal communications system which involves direct broadcast from a 'wrist watch radio' to a high-capacity, multibeam satellite for retransmission to ground communications centrals.

Fletcher, J. C.↗