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At least 1,171 records · Page 65

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NASA NTRS2008

The Challenges and Opportunities for International Cooperative Radio Science; Experience with Mars Express and Venus Express Missions

Radio Science is an opportunistic discipline in the sense that the communication link between a spacecraft and its supporting ground station can be used to probe the intervening media remotely. Radio science has recently expanded to greater, cooperative use of international assets. Mars Express and Venus Express are two such cooperative missions managed by the European Space Agency with broad international science participation supported by NASA's Deep Space Network (DSN) and ESA's tracking network for deep space missions (ESTRAK). This paper provides an overview of the constraints, opportunities, and lessons learned from international cross support of radio science, and it explores techniques for potentially optimizing the resultant data sets.

MEX↗

NASA NTRS2015

Reconfigurable, Cognitive Software-Defined Radio

Software-defined radio (SDR) technology allows radios to be reconfigured to perform different communication functions without using multiple radios to accomplish each task. Intelligent Automation, Inc., has developed SDR platforms that switch adaptively between different operation modes. The innovation works by modifying both transmit waveforms and receiver signal processing tasks. In Phase I of the project, the company developed SDR cognitive capabilities, including adaptive modulation and coding (AMC), automatic modulation recognition (AMR), and spectrum sensing. In Phase II, these capabilities were integrated into SDR platforms. The reconfigurable transceiver design employs high-speed field-programmable gate arrays, enabling multimode operation and scalable architecture. Designs are based on commercial off-the-shelf (COTS) components and are modular in nature, making it easier to upgrade individual components rather than redesigning the entire SDR platform as technology advances.

Bhat, Arvind↗

NASA NTRS2015

Fault-Tolerant Software-Defined Radio on Manycore

Software-defined radio (SDR) platforms generally rely on field-programmable gate arrays (FPGAs) and digital signal processors (DSPs), but such architectures require significant software development. In addition, application demands for radiation mitigation and fault tolerance exacerbate programming challenges. MaXentric Technologies, LLC, has developed a manycore-based SDR technology that provides 100 times the throughput of conventional radiationhardened general purpose processors. Manycore systems (30-100 cores and beyond) have the potential to provide high processing performance at error rates that are equivalent to current space-deployed uniprocessor systems. MaXentric's innovation is a highly flexible radio, providing over-the-air reconfiguration; adaptability; and uninterrupted, real-time, multimode operation. The technology is also compliant with NASA's Space Telecommunications Radio System (STRS) architecture. In addition to its many uses within NASA communications, the SDR can also serve as a highly programmable research-stage prototyping device for new waveforms and other communications technologies. It can also support noncommunication codes on its multicore processor, collocated with the communications workload-reducing the size, weight, and power of the overall system by aggregating processing jobs to a single board computer.

Ricketts, Scott↗

NASA NTRS2015

Programmable Ultra-Lightweight System Adaptable Radio

The programmable ultra-lightweight system adaptable radio (PULSAR) is a NASA Marshall Space Flight Center transceiver designed for the CubeSat market, but has the potential for other markets. The PULSAR project aims to reduce size, weight, and power while increasing telemetry data rate. The current version of the PULSAR has a mass of 2.2 kg and a footprint of 10.8 cm2. The height depends on the specific configuration. The PULSAR S-Band Communications Subsystem is an S- and X-band transponder system comprised of a receiver/detector (receiver) element, a transmitter element(s), and related power distribution, command, control, and telemetry element for operation and information interfaces. It is capable of receiving commands, encoding and transmitting telemetry, as well as providing tracking data in a manner compatible with Earthbased ground stations, near Earth network, and deep space network station resources. The software-defined radio's (SDR's) data format characteristics can be defined and reconfigured during spaceflight or prior to launch. The PULSAR team continues to evolve the SDR to improve the performance and form factor to meet the requirements that the CubeSat market space requires. One of the unique features is that the actual radio design can change (somewhat), but not require any hardware modifications due to the use of field programmable gate arrays.

Werkheiser, Arthur↗

NASA NTRS2016

Exploring Cognition Using Software Defined Radios for NASA Missions

NASA missions typically operate using a communication infrastructure that requires significant schedule planning with limited flexibility when the needs of the mission change. Parameters such as modulation, coding scheme, frequency, and data rate are fixed for the life of the mission. This is due to antiquated hardware and software for both the space and ground assets and a very complex set of mission profiles. Automated techniques in place by commercial telecommunication companies are being explored by NASA to determine their usability by NASA to reduce cost and increase science return. Adding cognition the ability to learn from past decisions and adjust behavior is also being investigated. Software Defined Radios are an ideal way to implement cognitive concepts. Cognition can be considered in many different aspects of the communication system. Radio functions, such as frequency, modulation, data rate, coding and filters can be adjusted based on measurements of signal degradation. Data delivery mechanisms and route changes based on past successes and failures can be made to more efficiently deliver the data to the end user. Automated antenna pointing can be added to improve gain, coverage, or adjust the target. Scheduling improvements and automation to reduce the dependence on humans provide more flexible capabilities. The Cognitive Communications project, funded by the Space Communication and Navigation Program, is exploring these concepts and using the SCaN Testbed on board the International Space Station to implement them as they evolve. The SCaN Testbed contains three Software Defined Radios and a flight computer. These four computing platforms, along with a tracking antenna system and the supporting ground infrastructure, will be used to implement various concepts in a system similar to those used by missions. Multiple universities and SBIR companies are supporting this investigation. This paper will describe the cognitive system ideas under consideration and the plan for implementing them on platforms, including the SCaN Testbed. Discussions in the paper will include how these concepts might be used to reduce cost and improve the science return for NASA missions.

transmitters receivers↗

NASA NTRS2016

Optical Tunable-Based Transmitter for Multiple Radio Frequency Bands

An optical tunable transmitter is used to transmit multiple radio frequency bands on a single beam. More specifically, a tunable laser is configured to generate a plurality of optical wavelengths, and an optical tunable transmitter is configured to modulate each of the plurality of optical wavelengths with a corresponding radio frequency band. The optical tunable transmitter is also configured to encode each of the plurality of modulated optical wavelengths onto a single laser beam for transmission of a plurality of radio frequency bands using the single laser beam.

Nguyen, Hung↗

NASA NTRS2016

Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0.3-30 keV) quiescent luminosity of the source is 8.9 x 10(exp 32) erg per sec for a distance of 2.4 kpc. The source shows clear variability on short timescales (an hour to a couple of hours) in the radio, soft X-ray, and hard X-ray bands in the form of multiple flares. The broadband X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having a photon index of gamma = 2.12 +/- 0.07 (90% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3 sigma confidence level with the e-folding energy of the cutoff as 20(sub -7)(sup +20) keV. Such curvature can be explained using synchrotron emission from the base of a jet outflow. Radio observations using the VLA reveal that the spectral index evolves on very fast timescales (as short as 10 minutes), switching between optically thick and thin synchrotron emission, possibly due to instabilities in the compact jet or stochastic instabilities in the accretion rate. We explore different scenarios to explain this very fast variability.

accretion disks↗

NASA NTRS2016

Search for Transient Gravitational Waves in Coincidence with Short-Duration Radio Transients During 2007-2013

We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO (Laser Interferometer Gravitational Wave Observatory), Virgo (Variability of Solar Irradiance and Gravity Oscillations) and GEO (German-UK Interferometric Detector) interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include star quakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.

Abbott, B. P.↗

NASA NTRS2017

Software Defined Radios - Architectures, Systems and Functions

Software Defined Radio is an industry term describing a method of utilizing a minimum amount of Radio Frequency (RF)/analog electronics before digitization takes place. Upon digitization all other functions are performed in software/firmware. There are as many different types of SDRs as there are data systems. Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 90's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast the foundations of transponder technology presently qualified for satellite applications were developed during the early space program of the 1960's. SDR technology offers potential to revolutionize satellite transponder technology by increasing science data through-put capability by at least an order of magnitude. While the SDR is adaptive in nature and is "One-size-fits-all" by design, conventional transponders are built to a specific platform and must be redesigned for every new bus. The SDR uses a minimum amount of analog/Radio Frequency components to up/down-convert the RF signal to/from a digital format. Once analog data is digitized, all processing is performed using hardware logic. Typical SDR processes include; filtering, modulation, up/down converting and demodulation. This presentation will show how the emerging SDR market has leveraged the existing commercial sector to provide a path to a radiation tolerant SDR transponder. These innovations will reduce the cost of transceivers, a decrease in power requirements and a commensurate reduction in volume. A second pay-off is the increased flexibility of the SDR by allowing the same hardware to implement multiple transponder types by altering hardware logic - no change of analog hardware is required - all of which can be ultimately accomplished in orbit. This in turn would provide high capability and low cost transponder to programs of all sizes.

Sims, William H.↗

NASA NTRS2017

The X-Ray Reflection Spectrum of the Radio-Loud Quasar 4C 74.26

The relativistic jets created by some active galactic nuclei are important agents of AGN feedback. In spite of this, our understanding of what produces these jets is still incomplete. X-ray observations, which can probe the processes operating in the central regions in the immediate vicinity of the supermassive black hole, the presumed jet launching point, are potentially particularly valuable in illuminating the jet formation process. Here, we present the hard X-ray NuSTAR observations of the radio-loud quasar 4C 74.26 in a joint analysis with quasi-simultaneous, soft X-ray Swift observations. Our spectral analysis reveals a high-energy cutoff of -183+3551 keV and confirms the presence of ionized reflection in the source. From the average spectrum we detect that the accretion disk is mildly recessed, with an inner radius of Rin4180 Rg. However, no significant evolution of the inner radius is seen during the three months covered by our NuSTAR campaign. This lack of variation could mean that the jet formation in this radio-loud quasar differs from what is observed in broad-line radio galaxies.

black hole physics â€“ galaxies: active â€“ quasar↗

NASA NTRS2017

Software Defined Radios - Architectures, Systems and Functions

Sims, Herb↗

NASA NTRS2017

Control and Non-Payload Communications (CNPC) Prototype Radio Verification Test Report

This report provides an overview and results from the verification of the specifications that defines the operational capabilities of the airborne and ground, L Band and C Band, Command and Non-Payload Communications radio link system. An overview of system verification is provided along with an overview of the operation of the radio. Measurement results are presented for verification of the radios operation.

avionics↗

NASA NTRS2018

Internal Radio-Frequency Instrumentation System (IRIS) Overview

Wireless instrumentation has long been sought for spaceflight applications, but practical implementations capable of providing the utility of wired sensors have proven elusive. The power needed to drive transmitters/receivers in traditional "active" wireless sensor radios requires either frequent battery replacement or prohibitive duty cycling. This prevents installing such sensors early in a vehicle's integration and treating them as always-on throughout its operation. "Passive" solutions such as radio frequency identification (RFID) techniques provide an appealing alternative, though most common RFID sensing approaches such as surface acoustic wave (SAW) RFID do not lend themselves easily to integrating arbitrary suites of sensors and sensor processors. In this talk we detail the design, fabrication, and evaluation of the Internal Radio-frequency Instrumentation System (IRIS), an RFID-enabled instrumentation solution that integrates an EPC Global Class 1 Generation 2 interface with processor-based wireless sensors. IRIS thermocouple sensors can operate in a low-power hibernation state with instantaneous over-the-air wakeup for nearly a decade on a small (255 mAh) coin cell battery. In their active state, they can acquire and stream 10 Hz data for more than 200 days. This allows wireless sensors to be installed and powered on early in vehicle integration and continue to operate after launch through a lengthy mission, opening the vehicle design trade space to wireless sensing in a meaningful and unprecedented way.

Wagner, Raymond↗

NASA NTRS2018

Coordinated Satellite Observations of the Very Low Frequency Transmission Through the Ionospheric D Layer at Low Latitudes, Using Broadband Radio Emissions from Lightning

Both ray theory and full-wave models of very low frequency transmission through the ionospheric D layer predict that the transmission is greatly suppressed near the geomagnetic equator. We use data from the low-inclination Communication/Navigation Outage Forecast System satellite to test this semiquantitatively, for broadband very low frequency emissions from lightning. Approximate ground-truthing of the incident wavefields in the Earth-ionosphere waveguide is provided by the World Wide Lightning Location Network. Observations of the wavefields at the satellite are provided by the Vector Electric Field Instrument aboard the satellite. The data set comprises whistler observations with the satellite at magnetic latitudes<26deg. Thus, our conclusions, too, must be limited to the near-equatorial region and are not necessarily predictive of midlatitude whistler properties. We find that in most broadband recordings of radio waves at the satellite, very few of the lightning strokes result in a detectable radio pulse at the satellite. However, in a minority of the recordings, there is enhanced transmission of very low frequency lightning emissions through the D layer, at a level exceeding model predictions by at least an order of magnitude. We show that kilometric-scale D-layer irregularities may be implicated in the enhanced transmission. This observation of sporadic enhancements at low magnetic latitude, made with broadband lightning emissions, is consistent with an earlier review of D-layer transmission for transmission from powerful man-made radio beacons.

Jacobson, Abram R.↗

NASA NTRS2019

The Second LBA Calibrator Survey of Southern Compact Extragalactic Radio Sources – LCS2

We present the second catalogue of accurate positions and correlated flux densities for 1100 compact extragalactic radio sources that were not observed before 2008 at high angular resolution. The catalogue spans the declination range [-90◦, -30◦] and was constructed from 19 24-h VLBI observing sessions with the Australian Long Baseline Array at 8.3 GHz. The catalogue presents the final part of the program that was started in 2008. The goals of that campaign were (1) to extend the number of compact radio sources with precise coordinates and measure their correlated flux densities, which can be used for phase referencing very long baseline interferometry (VLBI) and Atacama Large Millimeter/submillimeter Array (ALMA) observations, geodetic VLBI, search for sources with significant offsets with respect to Gaia positions, and space navigation; (2) to extend the complete flux-limited sample of compact extragalactic sources to the Southern hemisphere; and (3) to investigate the parsec-scale properties of sources from the high-frequency AT20G survey. The median uncertainty of the source positions is 3.5 mas. As a result of this VLBI campaign, the number of compact radio sources south of declination -40◦ that have measured VLBI-correlated flux densities and positions known to milliarcsecond accuracy has increased by over a factor of 6.

Petrov, Leonid↗

NASA NTRS2020

Space Telecommunications Radio System (STRS) Architecture, Tutorial Part 1 - Overview

Space Telecommunications Radio System (STRS) Architecture Standard provides a NASA standard forsoftware-defined radio. The STRS architecture has been demonstrated in the Space Communications and Navigation(SCaN) Testbed on the International Space Station as well as associated ground station radios. The STRS ArchitectureTutorial Overview presents a general introduction to the STRS architecture standard developed at the NASA GlennResearch Center (GRC), describes some of the main elements for STRS compliance, and addresses some frequentlyasked questions.. The STRS architecture should be used as a base for many of NASA s future telecommunicationstechnologies. The presentation will provide a basic understanding of STRS.

Handler, Louis M.↗

NASA NTRS2019

2 mm GISMO Observations of the Galactic Center. II. A Nonthermal Filament in the Radio Arc and Compact Sources

We have used the Goddard IRAM 2 Millimeter Observer (GISMO) with the 30 m IRAM telescope to carry out a 2 mm survey of the Galaxy’s central molecular zone. These observations detect thermal emission from cold interstellar medium dust, thermal free–free emission from ionized gas, and nonthermal synchrotron emission from relatively flat-spectrum sources. Archival data sets spanning 3.6 μm–90 cm are used to distinguish different emission mechanisms. After the thermal emission of dust is modeled and subtracted, the remaining 2 mm emission is dominated by free–free emission, with the exception of the brightest nonthermal filament (NTF) that runs through the middle of the bundle of filaments known as the Radio Arc. This is the shortest wavelength at which any NTF has been detected. The GISMO observations clearly trace this NTF over a length of ∼0°. 2, with a mean 2 mm spectral index that is steeper than at longer wavelengths. The 2 mm–6 cm (or 20 cm) spectral index steepens from α ≈ −0.2 to −0.7 as a function distance from the Sickle H II region, suggesting that this region is directly related to the NTF. A number of unresolved (at 21″) 2 mm sources are found nearby. One appears to be thermal dust emission from a molecular cloud that is associated with an enigmatic radio point source whose connection to the Radio Arc is still debated. The morphology and colors at shorter IR wavelengths indicate other 2 mm unresolved sources are likely to be compact H II regions.

Staguhn, Johannes↗

NASA NTRSDate not supplied

A Novel RF Architecture for Simultaneous Communication, Navigation, and Remote Sensing with Software-Defined Radio

The rapid growth of SmallSat and CubeSat missions at NASA has necessitated a re-evaluation of communication and remote-sensing architectures. Novel designs for CubeSat-sized single-board computers can now include larger Field-Programmable Gate Arrays (FPGAs) and faster System-on-Chip (SoCs) devices. These components substantially improve onboard processing capabilities so that varying subsystems no longer require an independent processor. By replacing individual Radio Frequency (RF) systems with a single software-defined radio (SDR) and processor, mission designers have greater control over reliability, performance, and efficiency. The presented architecture combines individual processing systems into a single design and establishes a modular SDR architecture capable of both remote-sensing and communication applications. This new approach based on a multi-input multi-output (MIMO) SDR features a scalable architecture optimized for Size, Weight, Power, and Cost (SWaP-C), with sufficient noise performance and phase-coherence to enable both remote-sensing and navigation applications, while providing a communication solution for simultaneous S-band and X-band transmission. This SDR design is developed around the NASA CubeSat Card Standard (CS2) that provides the required modularity through simplified backplane and interchangeable options for multiple radiation-hardened/tolerant processors. This architecture provides missions with a single platform for high-rate communication and a future platform to develop cognitive radio systems.

Advanced Avionics, Hybrid Processing, Data Process↗