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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS2023

Spatial Link Coverage Projections for the Glenn Research Center Communication Analysis Suite (GCAS)

Space communications are a fundamental part of every NASA mission, and reliable space communications are essential. Precise planning, simulation, and analysis of communications abilities are needed to know exactly what data rates, visibility times, and signal strength can be expected during the real missions. The goal of this work was to take a 3D icosphere, where each face was a point to be evaluated, and display the link performance onto a 2D projection of celestial bodies for links to a node location that could be spatially located at any of the icosahedral faces. 2D projections were produced for a wide range of spatial link grid sizes and compressed into low-size MAT files for ease of access and rapid implementation. The final icosahedral projections can be displayed onto various celestial body maps, using ultra-high-resolution maps for stitching. The results have proven satisfactory and are planned to support various simulation efforts.

communication link analysis↗
NASA NTRSDate not supplied

The Application of Photonic Lanterns in Free Space Optical Communications

Photonic lanterns offer an efficient solution to transition distorted light from free space into small aperture or single-mode waveguide devices. As a result, photonic lanterns can be useful for free space optical communications, where light is transmitted across a channel with varying atmospheric conditions. This paper will give an overview of studies using photonic lanterns in photon counting optical communication receivers where the detectors are small in aperture and fiber coupled. This paper will also survey other potential uses of photonic lanterns in coherent optical communication receivers or as wavefront sensors in adaptive optical systems.

Optical communications↗
NASA NTRSDate not supplied

Lunar Optical Communications

Numerous studies have shown that NASA’s Deep Space Network (DSN) is woefully inadequate to support the current pace of space exploration. Proposals are on the table for extensive infrastructure build-out using RF communications, which is ultimately bandwidth constrained. Optical communication offers unregulated, near-infinite bandwidth that can easily support the needs of humans at the Moon and beyond. Although not part of the proposed lunar network architecture, optical communication systems should be considered; these systems are operational now, quickly proliferating near Earth space (e.g. StarLink), and offer very high bandwidths.

lunar↗
NASA NTRSDate not supplied

xEMU Suit Integrated Audio Communications System: Ambient and EVA Pressure Testing System Performance

Testing across several airlock and EVA thermal and pressure scenarios has demonstrated that the Integrated Audio System of NASA’s Exploration Extravehicular Mobility Unit (xEMU) spacesuits transmits and receives intelligible audio communications without the use of a commcap or similar worn device. The xEMU audio system consists of internal loudspeakers and digital microphones (Integrated Communications System –ICS) combined with an adaptive Acoustic Echo Canceller (AEC), outbound voice operated transmission (VOX), and automatic gain control (AGC). Transducers are mounted in an “exploded commcap” configuration with helmet-attached speakers near the ears and three microphones positioned at the collar. The AGC removes inbound audio signals (e.g.,suit, Mission Control, Lander, C&W tones) from the outbound comms stream, reducing echo and feedback (squeal) in low-noise suit environments. The reduction of worn communication equipment increases crewmember comfort, range of movement, and situational awareness. However, test results also highlight the need for proper fan, duct, pump, and gas flow integration with suit acoustics and audio. Ductwork may serve as waveguides for various component and structure-borne noise. Sharply angled ducts can generate turbulent-flow noise. Gas flow from inlets above the crewmember’s head can generate noise when cascading over the faceplate and collar (or commcap) microphones. Sufficient acoustic noise levels (1) require increased gain to boost inbound audio, and (2) may distort signals resulting in AEC disruption or artifacts. Suit-noise levels decline with reduced pressure (density), but then elevated speech and audio effort/power become necessary. Whether the Integrated Audio System, commcap, or other device is used, suit acoustic noise can mask speech in outbound comms. This reduces intelligibility and requires other AECs/devices to suppress comms noise. Yet, adjusting a few components may yield significant improvement. We discuss xEMU audio functionality, demonstrate how acoustical treatment combined with inbound signal conditioning improved clarity during tests, and discuss future modifications.

xEMU↗
NASA NTRS2024

Modeling Entanglement-Based Quantum Key Distribution for the NASA Quantum Communications Analysis Suite

One of the most practical, and sought after, applications of quantum mechanics in the field of information science is the use of entanglement distribution to communicate quantum information effectively. Similar to the continued improvements of functional quantum computers over the past decade, advances in demonstrations of entanglement distribution over long distances may enable new applications in aeronautics and space communications. The existing NASA Quantum Communications Analysis Suite (NQCAS) software models such applications, but limited experimental data exists to verify the model’s theoretical results. There is, however, a large body of experimental data in the relevant literature for entanglement-based quantum key distribution (QKD). This paper details a Monte Carlo based QKD model that uses NQCAS input parameters to generate an estimated QKD link budget for verification of NQCAS. The model generates link budget statistics like key rates, error rates, and S values that can then be compared to the experimental values in the literature. Preliminary comparisons show many similarities between the simulated and experimental data, supporting the model’s validity. A verified NQCAS model will inform experimental work conducted in Glenn Research Center’s (GRC) NASA Quantum Metrology Laboratory (NQML), supporting the United States Quantum Initiative and potential NASA missions.

NASA Quantum Communications Analysis Suite↗
NASA NTRSDate not supplied

xEMU Suit Integrated Audio Communications System: Ambient and EVA Pressure Testing System Performance

Testing across several airlock and EVA thermal and pressure scenarios has demonstrated that the Integrated Audio System of NASA’s Exploration Extravehicular Mobility Unit (xEMU) spacesuits transmits and receives intelligible audio communications without the use of a commcap or similar worn device. The xEMU audio system consists of internal loudspeakers and digital microphones (Integrated Communications System –ICS) combined with an adaptive Acoustic Echo Canceller (AEC), outbound voice operated transmission (VOX), and automatic gain control (AGC). Transducers are mounted in an “exploded commcap” configuration with helmet-attached speakers near the ears and three microphones positioned at the collar. The AGC removes inbound audio signals (e.g.,suit, Mission Control, Lander, C&W tones) from the outbound comms stream, reducing echo and feedback (squeal) in low-noise suit environments. The reduction of worn communication equipment increases crewmember comfort, range of movement, and situational awareness. However, test results also highlight the need for proper fan, duct, pump, and gas flow integration with suit acoustics and audio. Ductwork may serve as waveguides for various component and structure-borne noise. Sharply angled ducts can generate turbulent-flow noise. Gas flow from inlets above the crewmember’s head can generate noise when cascading over the faceplate and collar (or commcap) microphones. Sufficient acoustic noise levels (1) require increased gain to boost inbound audio, and (2) may distort signals resulting in AEC disruption or artifacts. Suit-noise levels decline with reduced pressure (density), but then elevated speech and audio effort/power become necessary. Whether the Integrated Audio System, commcap, or other device is used, suit acoustic noise can mask speech in outbound comms. This reduces intelligibility and requires other AECs/devices to suppress comms noise. Yet, adjusting a few components may yield significant improvement. We discuss xEMU audio functionality, demonstrate how acoustical treatment combined with inbound signal conditioning improved clarity during tests, and discuss future modifications.

xEMU↗
NASA NTRSDate not supplied

Completion of NASA’s Two-Year Laser Communications Relay Demonstration (LCRD) Experiment Program

"The National Aeronautics and Space Administration’s (NASA) Laser Communications Relay Demonstration (LCRD) completed its two-year experiment program in June 2024. The LCRD geosynchronous payload includes two laser communications terminals interconnected via an onboard electronic switch. The payload relays data between two optical ground stations located in California and Hawaii and can also exchange data with an RF ground station in New Mexico. The addition of the Integrated LCRD Low-Earth Orbit (LEO) User Modem and Amplifier Terminal (ILLUMA-T) on the International Space Station in 2023 enabled data relay demonstrations between a laser terminal in low Earth orbit and either one of the optical ground stations or the RF ground station. The experiment program has included a variety of experiments originating within the LCRD project, NASA, and industry. The experiments have included measurements of the effects of the atmospheric optical channel (turbulence, weather) on the performance and availability of laser communications, adaptive optics characterization, demonstration of optimetrics techniques, and demonstration of Delay/Disruption Tolerant Networking (DTN). Furthermore, various future operational scenarios including robotic and exploration missions and various network service configurations have been emulated. This conference paper provides an overview and highlights of the LCRD experiment program with an emphasis on activities and results since the start of the ILLUMA-T testing in December 2023. A discussion of the expectations for the next phase of the LCRD mission, as well as how LCRD results may be applied to future applications is also included. LCRD is a joint project involving NASA Goddard Space Flight Center (GSFC), the California Institute of Technology Jet Propulsion Laboratory (JPL), and Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). "

Lasercom↗
NASA NTRSDate not supplied

Optimal Communication Topology Construction and Sensor Selection for Independent Airspace Surveillance

The paper presents an approach with no estimation feedback to sensors selection and communication network topology computation for independent airspace surveillance with maximum outcome and minimum cost using ground based distributed sensing, computing and communication network infrastructure. The selection criteria includes maximum airspace coverage with minimal resources, minimum communication time and power consumption while guaranteeing the system observability and providing in-time high quality information to both stationary and mobile users. The developed algorithms use multi-objective optimization strategy taking into account trade-offs between conflicting objectives and are implemented using off-the-shelf computational tools. The algorithms are validated in a desktop simulation environment using synthetic sensors data generated for a simulated multi-vehicle flight scenario in the selected regional airspace and parameters of a notional wireless communication network.

Distributed sensing↗
NASA NTRS1996

Optical Communications for Extreme Deep Space Missions

A recent study of deep space telecommunications systems was performed in support of NASA's Mission to the Solar System planing activity. The results show that high bandwidth communications (greater than 1Mbps) are feasible at high-value planetary targets provided there are investments in the ground and spacecraft communication infrastructure.

Optical Communications laser communications deep s↗
NASA NTRS1994

(abstract) Space Communications Technologies for Interstellar Missions

This paper will examine candidate communications architectures for potential interstellar missions in an effort to determine feasibility for such links and to identify likely technology advances that will be needed to support such endeavors. Examination of this challenging and futuristic communications problem may serve to guide the direction and advancement of space telecommunications technologies useful for other nearer-term applications.

architectures interstellar communications Daedalus↗
NASA NTRSDate not supplied

CLAIRE: Enabling Heterogeneous Communication Network Optimization for Robust and Resilient Operations

In this paper, we present the capabilities of the CLAIRE System which provides resilient communications for NASA in presence of interference and congestion for a heterogeneous multi-vendor network. CLAIRE increases mission science data return to improve resource efficiencies and ensures resilience in the unpredictable space environment for NASA missions and communication networks. CLAIRE provides technology / waveform agnostic cognitive control plane that is instantiated at the Application Layer (APP) so that it can ride on NASA’s HDTN bundle protocol or any other protocol stack that is used by the network. The cognitive control plane is instantiated using Heartbeats (HTBTs). CLAIRE is assisted by Wideband UHF-Ka Band RF Sensing that leverages advances in the Direct Digital Transceiver (DDTRX) technology. The Wideband RF Sensing is driven by statistical signal processing and machine learning algorithms. Interference is mitigated using Dynamic Spectrum Access (DSA). Finally, CLAIRE addresses congestion using spectrum aware packet forwarding algorithm. CLAIRE provides an extensible protocol that allows passing of RF spectrum situational awareness, cross-layer sensing, delay tolerant networking and dynamic spectrum access information that can help with network optimization. Cross-Layer Sensing (CLS) and CLAIRE Decision Engine (CDE) enable spectrum and delay aware packet forwarding and Dynamic Spectrum Access during cases of severe interference.

cognitive communications↗
NASA NTRS1971

Electromagnetic compatibility fundamentals applied to spacecraft radio communication systems

A design guide for minimizing electromagnetic interference in aerospace communication equipment for ground stations is presented. Specifically treated are the mechanisms of generating unwanted radio emissions that may affect station operations as well as other communications services, the mechanisms by which sensitive receivers become susceptible to interference, means for reducing interference, standard methods of measurement, and the problems of site selection. The sources of interference are viewed primarily as originating from communications transmitters aboard spacecraft and aircraft, ground transmitters within and outside the ground stations, and other electrical sources on the ground that are not intended to radiate.

Haber, F.↗
NASA NTRS1971

Program on application of communications satellites to educational development

Interdisciplinary research in needs analysis, communications technology studies, and systems synthesis is reported. Existing and planned educational telecommunications services are studied and library utilization of telecommunications is described. Preliminary estimates are presented of ranges of utilization of educational telecommunications services for 1975 and 1985; instructional and public television, computer-aided instruction, computing resources, and information resource sharing for various educational levels and purposes. Communications technology studies include transmission schemes for still-picture television, use of Gunn effect devices, and TV receiver front ends for direct satellite reception at 12 GHz. Two major studies in the systems synthesis project concern (1) organizational and administrative aspects of a large-scale instructional satellite system to be used with schools and (2) an analysis of future development of instructional television, with emphasis on the use of video tape recorders and cable television. A communications satellite system synthesis program developed for NASA is now operational on the university IBM 360-50 computer.

Morgan, R. P.↗
NASA NTRS1972

Separation and communications geometry analysis for a Jupiter entry probe from a Pioneer spacecraft

The separation and communications geometry analysis is presented which shows that it is possible to target a Jupiter entry probe from a Pioneer spin-stabilized vehicle to desired entry conditions and maintain a continuous line-of-sight communications link while the probe descends to a pressure of 10 bars within the atmosphere. Such a targeting is possible with either the deflected probe mode or with the deflected bus mode. For the nominal mission studied, an 800 day trip in 1978 with the Pioneer type spacecraft flying by a 1.3 R(J), it was possible to achieve entries near zero angle of attack at about -25 deg relative entry flight path angle. Because of the constraint on the deflection maneuver for the deflected probe mode, the deflection and phasing velocity requirements are much larger for this mode. The geometry parameters, look angles, ranges and range rates, provided by this analysis permit the design of a functional communications system for the bus and probe. Avoiding a high trapped radiation belt hazard at Jupiter by flying the bus by at 6 R(J), however, requires using a despun antenna on the flyby bus.

Tindle, E. L.↗
NASA NTRS1973

A system for analysis and classification of voice communications

A method for analysis and classification of verbal communications typically associated with manned space missions or simulations was developed. The study was carried out in two phases. Phase 1 was devoted to identification of crew tasks and activities which require voice communication for accomplishment or reporting. Phase 2 entailed development of a message classification system and a preliminary test of its feasibility. The classification system permits voice communications to be analyzed to three progressively more specific levels of detail and to be described in terms of message content, purpose, and the participants in the information exchange. A coding technique was devised to allow messages to be recorded by an eight-digit number.

Older, H. J.↗
NASA NTRS1973

An all digital low data rate communication system

The advent of digital hardwares has made it feasible to implement many communication system components digitally. With the exception of frequency down conversion, the proposed low data rate communication system uses digital hardwares completely. Although the system is designed primarily for deep space communications with large frequency uncertainty and low signal-to-noise ratio, it is also suitable for other low data rate applications with time-shared operation among a number of channels. Emphasis is placed on the fast Fourier transform receiver and the automatic frequency control via digital filtering. The speed available from the digital system allows sophisticated signal processing to reduce frequency uncertainty and to increase the signal-to-noise ratio. The practical limitations of the system such as the finite register length are examined. It is concluded that the proposed all-digital system is not only technically feasible but also has potential cost reduction over the existing receiving systems.

Chen, C.↗