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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Modular antenna pointing system for the Explorer platform satellite

A Modular Antenna Pointing System (MAPS) is described which was designed for on-orbit servicing and on-orbit exchange. The MAPS provides a data link between the Explorer Platform (EP) satellite and the Tracking and Data Relay Satellite (TDRS). The MAPS consists of a two axis gimbal set used fo position a High Gain Antenna (HGA) toward TDRS, system control electronics, and an extendable mast. The system was qualified and integrated with the EP satellite for an April 1992 launch.

Andrus, James↗
NASA NTRS1988

Development of a magnetically suspended, tetrahedron-shaped antenna pointing system

A magnetically suspended, tetrahedron-shaped antenna pointing system is proposed for use in a multibeam broadcasting satellite system in the future. The structure of this system is presented, along with its design concept and the functional test results which were obtained in a laser tracking system in the laboratory. According to these results, it has been confirmed that the system has many advantages over conventional systems and excellent performance.

Takahara, Kenichi↗
NASA NTRS2007

Multi-Antenna Radar Systems for Doppler Rain Measurements

Use of multiple-antenna radar systems aboard moving high-altitude platforms has been proposed for measuring rainfall. The basic principle of the proposed systems is a variant of that of along-track interferometric synthetic-aperture radar systems used previously to measure ocean waves and currents.

Durden, Stephen↗
NASA NTRS1983

Large space antenna communications systems: Integrated Langley Research Center/Jet Propulsion Laboratory development activities. 2: Langley Research Center activities

The electromagnetic analysis activities at the Langley Research Center are resulting in efficient and accurate analytical methods for predicting both far- and near-field radiation characteristics of large offset multiple-beam multiple-aperture mesh reflector antennas. The utilization of aperture integration augmented with Geometrical Theory of Diffraction in analyzing the large reflector antenna system is emphasized.

Cambell, T. G.↗
NASA NTRS1996

Modeling and analysis of the DSS-14 antenna control system

An improvement of pointing precision of the DSS-14 antenna is planned for the near future. In order to analyze the improvement limits and to design new controllers, a precise model of the antenna and the servo is developed, including a finite element model of the antenna structure and detailed models of the hydraulic drives and electronic parts. The DSS-14 antenna control system has two modes of operation: computer mode and precision mode. The principal goal of this investigation is to develop the model of the computer mode and to evaluate its performance. The DSS-14 antenna computer model consists of the antenna structure and drives in azimuth and elevation. For this model, the position servo loop is derived, and simulations of the closed-loop antenna dynamics are presented. The model is significantly different from that for the 34-m beam-waveguide antennas.

Gawronski, W.↗
NASA NTRS1996

Modeling and Analysis of the DSS-14 Antenna Control System

An improvement of pointing precision of the DSS-14 antenna is planned for the near future. In order to analyze the improvement limits and to design new controllers, a precise model of the antenna and the servo is developed, including a finite element model of the antenna structure and detailed models of the hydraulic drives and electronic parts. The DSS-14 antenna control system has two modes of operation: computer mode and precision mode. The principal goal of this investigation is to develop the model of the computer mode and to evaluate its performance. The DSS-14 antenna computer model consists of the antenna structure and drives in azimuth and elevation. For this model, the position servo loop is derived, and simulations of the closed-loop antenna dynamics are presented. The model is significantly different from that for the 34-m beam-waveguide antennas.

Gawronski, W.↗
NASA NTRS1986

Communications technology

The technologies for optimized, i.e., state of the art, operation of satellite-based communications systems are surveyed. Features of spaceborne active repeater systems, low-noise signal amplifiers, power amplifiers, and high frequency switches are described. Design features and capabilities of various satellite antenna systems are discussed, including multiple beam, shaped reflector shaped beam, offset reflector multiple beam, and mm-wave and laser antenna systems. Attitude control systems used with the antenna systems are explored, along with multiplexers, filters, and power generation, conditioning and amplification systems. The operational significance and techniques for exploiting channel bandwidth, baseband and modulation technologies are described. Finally, interconnectivity among communications satellites by means of RF and laser links is examined, as are the roles to be played by the Space Station and future large space antenna systems.

Cuccia, C. Louis↗
NASA NTRS1979

DSS 13 antenna monitor system

The development of a monitor system for the DSS 13 antenna is presented. The system checks for accumulator pressures, differential pressures, wind velocity, power supplies, fluid temperatures, and fluid levels. It was concluded that the system performed properly in high winds and correctly reported all malfunctions.

Siev, B.↗
NASA NTRS1963

The servo system for antenna positioning

This paper describes the servo system for pointing the horn-reflector antenna. It presents the general considerations which dictated the design and also describes the resulting system in some detail, giving the characteristics of the various parts of the system. Finally, the over-all performance of the servo system is discussed.

SERVOMECHANISM↗
NASA NTRS1995

ACTS aeronautical terminal experiment: System description and link analysis

During the summer of 1994, the performance of an experimental mobile satellite communication system was demonstrated to the industry and government representatives by the NASA Lewis Research Center (LeRC) and the Jet Propulsion Laboratory (JPL). The system was based on the Advanced Communications Technology Satellite (ACTS) and consisted of an K-/Ka-band active MMIC phased array antenna system, ACTS Mobile Terminal (AMT) and Link Evaluation Terminal (LET). A LeRC research aircraft, Learjet Model 25, was outfitted with the active MMIC phased array antenna system and AMT and served as the experimental 20/30 Ghz aeronautical terminal. The LET at LeRC in Cleveland, OH was interfaced with portions of fixed-AMT equipment and together provided the gateway station functions including ACTS satellite interface and Public Service Telephone Network (PSTN) interface. The ACTS was operated in its Microwave Switch Matrix (MSM) mode with a spot beam for the Learjet and another spot beam dedicated to the LET. The Learjet was flown over several major cities across the US and demonstrated the feasibility of full-duplex compressed voice link for an aeronautical terminal through the 20/30 Ghz ACTS satellite channel. This paper will present a technical description of the system including the MMIC phased array antenna system, AMT, Learjet, LET and ACTS satellite. The array antenna system consists of a 30 Ghz transmit array (LeRC/Texas Instruments) and two 20 Ghz receive arrays (USAF Rome Lab/Boeing and Martin Marietta), each one very small with sufficient performance for satellite voice link. The AMT consists of 2.4/4.8/9.6 Kbps voice coder/decoder, modem, PSTN interface and RF/IF converters. Link analysis will be presented and compared to the actual performance data collected during the demonstration flights.

Sohn, Philip↗
NASA NTRS1982

Autonomous antenna tracking system for mobile symphonie ground stations

The implementation of a satellite tracking and antenna control system is described. Due to the loss of inclination control for the symphonie satellites, it became necessary to equip the parabolic antennas of the mobile Symphonie ground station with tracking facilities. For the relatively low required tracking accuracy of 0.5 dB, a low cost, step track system was selected. The step track system developed for this purpose and tested over a long period of time in 7 ground stations is based on a search step method with subsequent parabola interpolation. As compared with the real search step method, the system has the advantage of a higher pointing angle resolution, and thus a higher tracking accuracy. When the pilot signal has been switched off for a long period of time, as for instance after the eclipse, the antenna is repointed towards the satellite by an automatically initiated spiral search scan. The function and design of the tracking system are detailed, while easy handling and tracking results.

Ernsberger, K.↗
NASA NTRS1994

Low-Earth-Orbiter resource allocation and capacity planning for the DSN using LEO4CAST

The Deep Space Network provides tracking and communication services for a number of U.S. and international low-Earth-orbiting (LEO) and near-Earth missions. This service is supplied by the 26-m subnet (located at each of the DSN complexes), the 9-m and the 34-m Antenna Research System antennas at Goldstone, and the 11-m antennas (following the orbital VLBI mission). An increasing number of LEO missions are planned for DSN support, which will result in increasingly complex ground resource allocation and mission support trades. To support TDA decision making on mission support and cost-effective ground system evolution for this 26-m subnet, LEO4CAST has been developed. LEO4CAST is a tool that uses statistical approaches to provide useful information for long-term ground system capacity planning and near-term resource allocation (prior to detailed time-of-day scheduling). LEO4CAST is currently beta-test software and is being exercised by both the Office of Telecommunications and Data Acquisition (TDA) and the JPL Systems Division.

Fox, G.↗