Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “optical communication systems”

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.

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

At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

An optical disk archive for a data base management system

An overview is given of a data base management system that can catalog and archive data at rates up to 50M bits/sec. Emphasis is on the laser disk system that is used for the archive. All key components in the system (3 Vax 11/780s, a SEL 32/2750, a high speed communication interface, and the optical disk) are interfaced to a 100M bits/sec 16-port fiber optic bus to achieve the high data rates. The basic data unit is an autonomous data packet. Each packet contains a primary and secondary header and can be up to a million bits in length. The data packets are recorded on the optical disk at the same time the packet headers are being used by the relational data base management software ORACLE to create a directory independent of the packet recording process. The user then interfaces to the VAX that contains the directory for a quick-look scan or retrieval of the packet(s). The total system functions are distributed between the VAX and the SEL. The optical disk unit records the data with an argon laser at 100M bits/sec from its buffer, which is interfaced to the fiber optic bus. The same laser is used in the read cycle by reducing the laser power. Additional information is given in the form of outlines, charts, and diagrams.

Thomas, Douglas T.↗
NASA NTRS1993

Wavelength-Division Multiplexing Of Avionic Digital Control Signals

Proposed wavelength-division multiplexing optoelectronic system aboard aircraft transmits digital control signals from central flight-control computer via optical fibers to multiple distributed processors, actuators, and sensors. In comparison with serial TDM communication systems, this system offers potentially higher data throughput, greater tolerance to transient induced faults, and lower bit-error rates. Also immune to electromagnetic interference at suboptical frequencies.

Patterson, James D.↗
NASA NTRS2020

In Silico Methods for Space System Analysis: Optical Link Coding Performance and Lunar Terrain Masks

As deep space links migrate toward higher frequency bands like 𝐾𝑎 and optical, thor- ough trade-space exploration becomes increasingly valuable for designing reliable and efficient communications systems. In this contribution, we leveraged high-performance, concurrent simulations when the run-time complexity of simulation software overwhelms capabilities of ordinary desktop machines. The first part of this manuscript describes how to run error correcting code simulations concurrently on a high-performance supercomputer. The second part of this study describes a framework to produce azimuth and elevation terrain masks from imagery of the Lunar South Pole.

Michels, Dominik L↗
DOE OSTI2020

Opportunistic Hybrid Communications Systems for Distributed PV Coordination

A full-scale, operational implementation of the opportunistic hybrid communications systems for distributed photovoltaic (PV) coordination was successfully developed, simulated, and validated in this 3-year project. The system is considered hybrid because it uses different communications pathways from the scale of residential PV inverters to a transmission network; primary technologies harnessed include Low-Power Wireless Personal Area Network (LoWPAN), Power Line Communication (PLC), WiFi mesh, Worldwide Interoperability for Microwave Access (WiMAX), Ethernet cable, and Optical Ethernet systems. It is opportunistic in that it chooses to route messages through each of these systems based on recent data about latency and availability to ensure reliable message passing.

14 SOLAR ENERGY↗
NASA NTRS1995

Phase Locking of a Second Harmonic Gyrotron Using a Quasi-Optical Circulator

The benefits of high power millimeter wave radiation for use in communication and radar systems are well known. Recently a frequency near 35 GHz was allotted for use in deep space communications, including bands for spacecraft uplink and downlink. Described is the phase locking of a high power pulsed gyrotron oscillator through the use of a quasi-optical circulator (using a second harmonic gyrotron).

35↗
NASA NTRS1993

Advanced communication satellites worldwide - Satellites of opportunity for the ACTS mobile terminal

Space agencies worldwide are involved in advanced satellite communication systems. This paper presents an overview of these satellites and related technologies in the U.S., Europe, and Japan. They are geostationary satellites using high frequency bands such as K/Ka (20/30 GHz) and O-band (millimeter wave), as well as optical frequencies. The similarity of these programs demonstrate a common interest to develop large capacity satellite communication systems, and shows that closer international cooperation could be set up. The ACTS Mobile Terminal (AMT) project discussed here is such an example. The AMT's compatibility with satellites other than ACTS has been studied, and a proposed common experiment is presented here. The Japanese Engineering Test Satellite ETS-VI has been identified as the best initial 'satellite of opportunity' for AMT in this preliminary assessment.

Girardey, Catherine C.↗
NASA NTRS1972

Study of optimum methods of optical communication

Optimum methods of optical communication accounting for the effects of the turbulent atmosphere and quantum mechanics, both by the semi-classical method and the full-fledged quantum theoretical model are described. A concerted effort to apply the techniques of communication theory to the novel problems of optical communication by a careful study of realistic models and their statistical descriptions, the finding of appropriate optimum structures and the calculation of their performance and, insofar as possible, comparing them to conventional and other suboptimal systems are discussed. In this unified way the bounds on performance and the structure of optimum communication systems for transmission of information, imaging, tracking, and estimation can be determined for optical channels.

Harger, R. O.↗
NASA NTRS1971

Optical devices - Lasers. A compilation

Laser applications in communications, industrial fabrication, and computer systems, and laser beam generation and control - technology utilization

Source record↗
NASA NTRSDate not supplied

Latest Status of the CCSDS Optical Communications Working Group

International civil space agencies around the world are working together in the Interagency Operation Advisory Group (IOAG) and the Consultative Committee for Space Data Systems (CCSDS) to develop interoperability architectures and standards for space communications. Within CCSDS, there is a working group dedicated on developing recommendations and standards for optical communications. These standards include recommendations for the physical layer, coding and synchronization layer, and best practices for measuring and monitoring atmospheric conditions and operating optical links. The working group has developed standards for both Near Earth and deep space robotic and hum exploration missions. The standards generally address both free space links between spacecraft and free space links between spacecraft and ground. This paper will provide an overview and update on the set of standards the CCSDS Optical Communications Working Group has developed

Bernard L Edwards↗
NASA NTRS2005

NASA Tech Briefs, October 2005

Topics covered include: Insect-Inspired Optical-Flow Navigation Sensors; Chemical Sensors Based on Optical Ring Resonators; A Broad-Band Phase-Contrast Wave-Front Sensor; Progress in Insect-Inspired Optical Navigation Sensors; Portable Airborne Laser System Measures Forest-Canopy Height; Deployable Wide-Aperture Array Antennas; Faster Evolution of More Multifunctional Logic Circuits; Video-Camera-Based Position-Measuring System; N-Type delta Doping of High-Purity Silicon Imaging Arrays; Avionics System Architecture Tool; Updated Chemical Kinetics and Sensitivity Analysis Code; Predicting Flutter and Forced Response in Turbomachinery; Upgrades of Two Computer Codes for Analysis of Turbomachinery; Program Facilitates CMMI Appraisals; Grid Visualization Tool; Program Computes Sound Pressures at Rocket Launches; Solar-System Ephemeris Toolbox; Data-Acquisition Software for PSP/TSP Wind-Tunnel Cameras; Corrosion-Prevention Capabilities of a Water-Borne, Silicone-Based, Primerless Coating; Sol-Gel Process for Making Pt-Ru Fuel-Cell Catalysts; Making Activated Carbon for Storing Gas; System Regulates the Water Contents of Fuel-Cell Streams; Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig; Modifications of Fabrication of Vibratory Microgyroscopes; Chamber for Growing and Observing Fungi; Electroporation System for Sterilizing Water; Thermoelectric Air/Soil Energy-Harvesting Device; Flexible Metal-Fabric Radiators; Actuated Hybrid Mirror Telescope; Optical Design of an Optical Communications Terminal; Algorithm for Identifying Erroneous Rain-Gauge Readings; Condition Assessment and End-of-Life Prediction System for Electric Machines and Their Loads; Lightweight Thermal Insulation for a Liquid-Oxygen Tank; Stellar Gyroscope for Determining Attitude of a Spacecraft; and Lifting Mechanism for the Mars Explorer Rover.

Source record↗
NASA NTRS2016

Photonic Integrated Circuit (PIC) Device Structures: Background, Fabrication Ecosystem, Relevance to Space Systems Applications, and Discussion of Related Radiation Effects

Electronic integrated circuits are considered one of the most significant technological advances of the 20th century, with demonstrated impact in their ability to incorporate successively higher numbers transistors and construct electronic devices onto a single CMOS chip. Photonic integrated circuits (PICs) exist as the optical analog to integrated circuits; however, in place of transistors, PICs consist of numerous scaled optical components, including such "building-block" structures as waveguides, MMIs, lasers, and optical ring resonators. The ability to construct electronic and photonic components on a single microsystems platform offers transformative potential for the development of technologies in fields including communications, biomedical device development, autonomous navigation, and chemical and atmospheric sensing. Developing on-chip systems that provide new avenues for integration and replacement of bulk optical and electro-optic components also reduces size, weight, power and cost (SWaP-C) limitations, which are important in the selection of instrumentation for specific flight projects. The number of applications currently emerging for complex photonics systems-particularly in data communications-warrants additional investigations when considering reliability for space systems development. This Body of Knowledge document seeks to provide an overview of existing integrated photonics architectures; the current state of design, development, and fabrication ecosystems in the United States and Europe; and potential space applications, with emphasis given to associated radiation effects and reliability.

Body of Knowledge (BOK)↗
NASA NTRS1980

Research and Technology 1980

Topics are divided into three major areas: Earth resources, advanced development, and technology transfer. Topics include: aerial color infrared photography, fiber optics, lightning research, soil mechanics, corrosion prevention, image processing, and communication systems development.

Source record↗
NASA NTRS1986

A simple method for designing or analyzing an optical communication link

A simple method is described for determining the performance of a free space optical communication link. The method can be used either in the system design (synthesis) mode or in the performance evaluation (analysis) mode. Although restricted to photo counting based detection of pulse position modulated signals, the method is still sufficiently general to accommodate space-based, as well as ground-based, reception.

Lesh, J. R.↗
NASA NTRS1986

Simple method for designing or analyzing an optical communication link

A simple method is described for determining the performance of a free space optical communication link. The method can be used either in the system design (synthesis) mode, or in the performance evaluation (analysis) mode. Although restricted to photo counting based detection (e.g., photomultiplier tube or equivalent) of pulse position modulated signals, the method is still sufficiently general to accommodate space-based, as well as ground-based, reception.

Lesh, James R.↗
NASA NTRS1993

Quasi-optical grids with thin rectangular patch/aperture elements

Theoretical analysis is presented for an efficient and accurate performance evaluation of quasi-optical grids comprised of thin rectangular patch/aperture elements with/without a dielectric substrate/superstrate. The convergence rate of this efficient technique is improved by an order of magnitude with the approximate edge conditions incorporated in the basis functions of the integral equation solution. Also presented are the interesting applications of this efficient analytical technique to the design and performance evaluation of the coupling grids and beam splitters in the optical systems as well as thermal protection sunshields used in the communication systems of satellites and spacecrafts.

Wu, Te-Kao↗
NASA NTRS1993

Conversion of the proprietary ROLM (tm) inter-node link from multimode to singlemode operation

Many NASA centers have selected ROLM(TM) Computerized Branch Exchanges (CBX's) as their standard telephone exchange. The ROLM 9751 CBX Model 70 with ROLM software release 9005 can inter-communicate as a 'multi-node' system over a multimode fiber optic link of 450 to 6,000 meters. Singlemode fiber installations are not supported by ROLM. Two New Mexico-based NASA satellite ground terminals were already connected via a 6 kilometer singlemode fiber optic link. The ROLM Inter-Node Link (INL) was converted from multimode LED transmitters to singlemode laser transmitters and two ROLM CBX systems were interconnected using the modified INL. On activation, the system operated normally and has done so for six months. System testing indicates sufficient margin to drive 45 kilometers of singlemode fiber, an important benefit for widely separated facilities.

Boucher, Larry↗