Optical communication potential.
Lasers for wideband planetary communication, describing heterodyne receiver and transmitter designs
LASER COMMUNICATION↗
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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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SCAILET - An intelligent assistant for satellite ground terminal operations
Space communication artificial intelligence for the link evaluation terminal (SCAILET) is an experimenter interface to the link evaluation terminal (LET) developed by NASA through the application of artificial intelligence to an advanced ground terminal. The high-burst-rate (HBR) LET provides the required capabilities for wideband communications experiments with the advanced communications technology satellite (ACTS). The HBR-LET terminal consists of seven major subsystems and is controlled and monitored by a minicomputer through an IEEE-488 or RS-232 interface. Programming scripts configure HBR-LET and allow data acquisition but are difficult to use and therefore the full capabilities of the system are not utilized. An intelligent assistant module was developed as part of the SCAILET module and solves problems encountered during configuration of the HBR-LET system. This assistant is a graphical interface with an expert system running in the background and allows users to configure instrumentation, program sequences and reference documentation. The simplicity of use makes SCAILET a superior interface to the ASCII terminal and continuous monitoring allows nearly flawless configuration and execution of HBR-LET experiments.
Shahidi, A. K.↗
LANDSAT-D flight segment operations manual, volume 1
Hardware, systems, and subsystems for the multimission modular spacecraft used for LANDSAT 4 are described and depicted in block diagrams and schematics. Components discussed include the modular attitude control system; the communication and data handling subsystem; the narrowband tape recorder; the on-board computer; the propulsion module subsystem; the signal conditioning and control unit; the modular power subsystem; the solar array drive and power transmission assembly; the power distribution unit; the digital processing unit; and the wideband communication subsystem.
Varhola, J.↗
Numerical aerodynamic simulation program long haul communications prototype
This document is a report of the Numerical Aerodynamic Simulation (NAS) Long Haul Communications Prototype (LHCP). It describes the accomplishments of the LHCP group, presents the results from all LHCP experiments and testing activities, makes recommendations for present and future LHCP activities, and evaluates the remote workstation accesses from Langley Research Center, Lewis Research Center, and Colorado State University to Ames Research Center. The report is the final effort of the Long Haul (Wideband) Communications Prototype Plan (PT-1133-02-N00), 3 October 1985, which defined the requirements for the development, test, and operation of the LHCP network and was the plan used to evaluate the remote user bandwidth requirements for the Numerical Aerodynamic Simulation Processing System Network.
Cmaylo, Bohden K.↗
A 10.6 micron laser-receiver RF subsystem
One of the problems inherent in the use of optical communication systems is the exceedingly high Doppler shift which can be expected. With the recent development of stable, linear, octavebandwidth, voltage-tunable oscillators, this problem has been solved. A laboratory tracking receiver which is capable of tracking a 1-GHz frequency shift at rates up to 12 MHz/s with subsequent coherent data demodulation was designed and tested. This work demonstrates that the design and fabrication of an RF subsystem, utilizing coherent demodulation of data, for wideband communications systems is now both feasible and practical.
Santarpia, D. E.↗
Wideband, high efficiency optical modulator requires less than 10 watts drive power
Wideband optical modulation system operates with less than 10-watts drive power. It consists of an optical modulator and transistorized driver that combines small cross-section potassium dideuterium phosphate crystals with laser beam-condensing optics. Optical modulation systems may serve importantly in future space wideband communication systems.
Becknell, W. E.↗
A wideband Gaussian noise generator utilizing simultaneously generated pn-sequences.
A digital system has been constructed for the generation of wideband Gaussian noise with a spectrum which is flat to within plus or minus 0.5 dB from 0 to 10 MHz. These characteristics are substantially better than those of commercially available analog noise generators, and are required in testing and simulation of wideband communications systems. The noise is generated by the analog summation of thirty essentially independent binary waveforms, clocked at 35 MHz, and low-pass filtered to 10 MHz.
Hurd, W. J.↗
Design/cost tradeoff studies. Appendix A. Supporting analyses and tradeoffs, book 1. Earth Observatory Satellite system definition study (EOS)
A listing of the Earth Observatory Satellite (EOS) candidate missions is presented for use as a baseline in describing the EOS payloads. The missions are identified in terms of first, second, and third generation payloads. The specific applications of the EOS satellites are defined. The subjects considered are: (1) orbit analysis, (2) space shuttle interfaces, (3) thematic mapping subsystem, (4) high resolution pointable imager subsystem, (5) the data collection system, (6) the synthetic aperture radar, (7) the passive multichannel microwave radiometer, and (8) the wideband communications and handling equipment. Illustrations of the satellite and launch vehicle configurations are provided. Block diagrams of the electronic circuits are included.
Source record↗
Earth Observatory Satellite system definition study. Report 5: System design and specifications. Volume 4: Mission peculiar spacecraft segment and module specifications
The specifications for the Earth Observatory Satellite (EOS) peculiar spacecraft segment and associated subsystems and modules are presented. The specifications considered include the following: (1) wideband communications subsystem module, (2) mission peculiar software, (3) hydrazine propulsion subsystem module, (4) solar array assembly, and (5) the scanning spectral radiometer.
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Networks systems and operations
The application of wideband communication techniques for data links with satellites is discussed. A diagram of the demand assigned voice communications system is provided. The development of prototype integrated spacecraft paramps at S- and C-bands is described and the performance of space-qualified paramps is tabulated. The characteristics of a dual parabolic cylinder monopulse zoom antenna for use with the tracking and data relay satellite system (TDRSS) are analyzed. The development of a universally applicable transponder at S-band is reported. A block diagram of the major subassemblies of the S-band transponder is included. The technology aspects of network timing and synchronization of communication systems are to show the use of the Omega navigation system. The telemetry data compression system used during the Skylab program is evaluated.
Source record↗
Landsat 2 on-board computer
The Landsat Spacecraft Project (formerly known as ERTS) was based essentially on the use of Nimbus spacecraft hardware. It was soon recognized that the availability of only 30 stored command locations (which were sufficient for the Nimbus mission) would limit the operation of the Landsat 1 mission with much higher power sensors, recorders, and wideband communications being cycled on and off throughout the orbit. The solution described is a simple memory with hard wired logic, of a design that can interface with the existing hardware, without modifications. The design was implemented using an existing APO (Advanced Onboard Processor) and a 4096 word X 18 bit plated wire memory. (The AOP has been subsequently designated the NASA Standard Spacecraft Computer.)
Lesko, J. G., Jr.↗
An operational video data compression system for ATS and ITOS
An operational data compression system has been developed and implemented for transmission of digitized ATS and ITOS-VHRR satellite video data over the wideband communication link between the Wallops Island, Va. Command and Data Acquisition Station and the National Environmental Satellite Service at Suitland, Md. This system uses minicomputers for the coding and decoding of the data to achieve maximum flexibility together with specially designed interface equipment for greater efficiency. No loss in data quality occurs due to the compression, and, in certain cases, data is transmitted which would be otherwise unavailable due to the limited channel capacity. This paper describes the method of compression, the equipment used, and the compression results attained.
Kutz, R. L.↗
Office of Space Tracking and Data Systems
A brief overview of the Office of Space Tracking and Data Systems support functions is given along with a description of the Spaceflight Tracking and Data Network and the Deep Space Network. Preparations for upcoming missions, wideband communications, and Tracking and Data Relay Satellite Systems are discussed.
Source record↗
Horn antenna design studies. Citations from the International Aerospace Abstract data base
These citations from the international literature describe the antenna radiation patterns, polarization characteristics, wave propagation, noise temperature, wave diffraction, and wideband communication of various horn antennas. This updated bibliography contains 217 citations, 63 of which are new entries to the previous edition.
Gallagher, M. K.↗
Landsat-D, about to be reality
The space and ground segments of the Landsat-D thematic mapper (TM) for remote sensing of a 185 km swath with 30 m resolution are described. Scanning the full earth once every 16 days from its 705 km sunsynchronous orbit, Landsat-D will relay its data on the ku-band through the TDRSS satellite to a ground station. The X-band will also be used to transmit data directly to foreign and domestic ground stations; the S-band will be reserved for MSS data only. Landsat-D comprises the multimission modular spacecraft and the instrument module, which features the MSS and TM, a wideband communication subsystem, a solar array, and an L-band global positioning system. Three computers on the ground provide a high degree of automation for reception, storage, retrieval, back-up, and transmission of data and commands. Additionally, a van is equipped with transportable equipment, including an antenna. Procedures followed for image generation from the MSS and TM are detailed, noting storage at Goddard until dispersal of tapes under the direction of the EROS data center.
Aepli, T. C.↗
A user's view of optical disc applications
An overall space information system is considered. It is found that data storage is required in all elements of the system with the possible exception of the wideband communication link. The data capture facility is the first ground facility to handle space-acquired data. A typical nine-day Spacelab mission is expected to generate up to 10 to the 13th bits of data. The current storage medium for this data is approximately 4000 magnetic tapes. It is pointed out that optical disk storage provides an attractive alternative to magnetic disk and tape storage. Options to install an optical disk storage system in the GSFC data capture facility in the 1986 time frame are evaluated by NASA. Attention is given to data capture and data base applications, onboard data storage applications, and numerical computation applications.
Holcomb, L. B.↗
Direction Finding Using an Antenna with Direction Dependent Impulse Response
Wideband antennas may be designed to have an impulse response that is direction dependent, not only in amplitude but also in waveform shape. This property can be used to perform direction finding using a single fixed antenna, without the need for an array or antenna rotation. In this paper direction finding is demonstrated using a simple candelabra-shaped monopole operating in the 1-3 GHz range. The method requires a known transmitted pulse shape and high signal-to-noise ratio, and is not as accurate or robust as conventional methods. However, it can add direction finding capability to a wideband communication system without the addition of any hardware.
spacecraft/cubesat RF sensing and Communications↗
Results of tests performed with Relay I at the KDD Space Communications Station
Wideband receiving experiments performed with Relay I satellite at Kokusai Denshin Denwa space communication ground station
GROUND STATION↗