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Results for “RADIO FREQUENCY MONITORING”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Dynamics of argon metastables in Ar–CH 4 radio frequency capacitively-coupled plasma: real-time monitoring with neural network-augmented broadband optical emission spectroscopy

In moderate-pressure radio frequency (RF) capacitively coupled plasmas generated in argon–methane mixtures, the density of argon metastable atoms (Ar 1 s 5 ) exhibits a non-monotonic dependence on methane (CH 4 ) concentration. Laser-induced fluorescence (LIF) was used to measure and compare local Ar 1 s 5 densities in Ar and Ar–CH 4 plasmas at 2.6 Torr and RF powers of 17–117 W. The addition of 1% CH 4 increases the metastable density, and 2% CH 4 triggers a strong depletion by an order of magnitude, compared to 1% CH 4 case. This non-monotonic behavior demonstrates the sensitivity of metastable populations to small gas admixtures, which is critical for processes where metastables drive precursor dissociation. For real-time monitoring of metastable population, broadband optical emission spectroscopy (OES) is augmented with a feedforward neural network (NN) to predict Ar s1 5 densities from spectral features. When trained on LIF data, the NN replicates the absolute densities and the dynamic trends of Ar 1 s 5 density variation. The NN-augmented broadband OES approach can be used as a simple and cost-effective tool for tracking Ar metastables in Ar-rich plasmas, facilitating industrial-scale optimization.

Yatom, Shurik [Princeton Plasma Physics Laboratory↗
DOE OSTI2025

Radio Frequency Field Programable Gate Array Implementation of Reflectometry Cable Monitoring

This document describes the development of a field programable gate array (FPGA) radio frequency system on a chip (RF SoC) adaptation and evaluation of the single-board device to perform both Frequency Domain Reflectometry (FDR) and Spread Spectrum Time Domain Reflectometry (SSTDR) for offline and online cable testing. The work builds on and leverages the work of Pacific Northwest National Laboratory (PNNL) in airport millimeter wave technology by using the same development hardware employed in that program. The work is performed under sponsorship from the U.S. Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) program and the task objective is to confirm and demonstrate feasibility to adapt FPGA technology for a cost-effective multiplexed single-board electronic module to perform cable tests that are equivalent to commercial and laboratory test instruments for FDR and SSTDR cable tests. The developed 2-channel (extendable to 7 channels) system was compared to dedicated and proven test instruments and shown to produce equivalent results on a range of cables and with a range of damage types. The FPGA reflectometry test board is one of several technologies that could facilitate implementation of online monitoring of safety critical cable systems.

42 ENGINEERING↗
DOE OSTI2022

Gas-filled radio-frequency beam detector

A system for monitoring intensity of a particle beam can include one or more radio-frequency (RF) detectors coupled to a signal analyzer that can be placed outside the radiation field of the particle beam. Each RF detector can include a gas-filled RF cavity coupled to one or more gas-filled waveguides. The signal analyzer can self-calibrate before the particle beam is turned on for determining one or more absolute intensities of the particle beam when the particle beam is present.

Yonehara, Katsuya↗
DOE OSTI2024

Augmented Human Analysis (AHA)

Radio frequency (RF) signal monitoring generally emphasizes intentionally generated signals, such as WiFi, Bluetooth, or cellular transmissions. However, electronic devices also produce unintended radiated emissions (UREs), which could also be useful in RF spectrum analysis. In either case, deriving intelligence from RF signals is typically a human-intensive process requiring significant domain knowledge. In the Augmented Human Analysis (AHA) project, we investigate the utility of dimensionally aligned signal projection (DASP) and machine learning (ML) algorithms for accelerating RF analysis workflows. We find that while DASP algorithms can indeed highlight signal characteristics relevant for classification tasks, the choice of algorithmic hyperparameters greatly affects performance. To address this challenge, we evaluate the quality of DASP outputs using the silhouette score, which measures how well data points cluster; high silhouette scores indicate good clustering, and thus good hyperparameter values. This approach is critical for machine learning pipelines as the DASP parameters cannot be directly optimized during model training. By identifying good DASP parameters, and thus good DASP outputs, as a preprocessing step, we can decrease the amount of effort required for downstream ML model training. We demonstrate our workflow using a dataset of UREs from common household devices, showing that even without the aid of ML, proper selection of DASP parameters enables clustering by device type.

42 ENGINEERING↗
NASA NTRS1993

Eddy-Current Monitoring Of Composite Layups

Eddy-current-probe apparatus used to determine predominant orientations of fibers in fiber/matrix composite materials. Apparatus nondestructive, noninvasive means for monitoring composite prepregs and layups during fabrication to ensure predictable and repeatable mechanical properties of finished composite panels. Consists essentially of electromagnet coil wrapped around horseshoe-shaped powdered-iron or ferrite ore. Optionally, capacitor included in series or parallel with coil to form resonant circuit. Impedance monitor excites radio-frequency current in coil and measures impedance of probe circuit. Affected by whatever material placed near ends of core, where material intercepts alternating magnetic field excited in core by current in coil.

Fox, Robert L.↗
NASA NTRS1996

Simultaneous X-Ray and Radio Observations of the Unusual Binary LSI + 61 deg 303

We present simultaneous 0.5 - 10 keV X-ray and two-frequency radio observations at 2.25 and 8.3 GHz of the unusual binary system LSI + 61 deg. 303. This system was observed twice in a single binary orbit by the ASCA satellite, and monitored daily at two radio frequencies during the same orbital cycle with the Greenbank Interferometer. During the first ASCA observation the source was detected with a 1 - 10 keV luminosity 3.6 x 10(exp 33) (d/2.0 kpc)(exp 2) erg 1/s and during the second at a similar level with evidence for a decrease in average flux of 30%. During the first pointing the radio source was at a quiescent 8 GHz flux level of 30 mJy while during the second the radio flux was rising dramatically with an average value of 100 mJy. No variability is seen in the X-ray flux during the first pointing, but during the second the flux is variable by approx. 50% on timescales of approx. 30 minutes. No pulsations are seen in either X-ray observation with an upper limit on pulsed flux of 20%. The low X-ray luminosity and lack of observed pulsations indicate that accretion onto a neutron star surface is not the origin for the high-energy emission. Rather, the X-rays must result either from accreted matter which is stopped at the magnetosphere because the magnetospheric boundry is rotating at super-Keplerian rates or due to a shock formed in the interaction of the dense wind of the Be star companion and a moderately young pulsar. We derive a required pulsar spin down luminosity of approx. 10(exp 37) erg 1/s, and argue that the shock model more easily explains the observed X-ray radio observations.

Harrison, Fiona A.↗
NASA NTRS1996

ASCA Observations of the Unusual Binary LSI+61 Deg 303

We present simultaneous 0.5-10 keV X-ray and two-frequency radio observations at 2.25 and 8.3 GHz of the unusual binary system LSI+61 deg 303. This system was observed twice in a single binary orbit by the ASCA satellite, and monitored daily at two radio frequencies during the same orbital cycle with the Greenbank Interferometer. During the first ASCA observation the source was detected with a 1-10 keV luminosity 3.6 x 10(exp 33) (d/2.0 kpc )(exp 2) erg/s and during the second at a similar level with evidence for a decrease in average flux of 30%. During the first pointing the radio source was at a quiescent 8 GHz flux level of 30 mJy while during the second the radio flux was rising dramatically with an average value of 100 mJy. No variability is seen in the X-ray flux during the first pointing, but during the second the flux is variable by approx. 50% on timescales of approx. 30 minutes. No pulsations are seen in either X-ray observation with an upper limit on pulsed flux of 20% . The low X-ray luminosity and lack of observed pulsations indicate that accretion onto a neutron star surface is not the origin for the high-energy emission. Rather, the X-rays must result either from accreted matter which is stopped at the magnetosphere because the magnetospheric boundary is rotating at super-Keplerian rates or due to a shock formed in the interaction of the dense wind of the Be star companion and a moderately young pulsar.

Harrison, Fiona A.↗
NASA NTRS1982

NASA Deep Space Network performance analysis

As part of the Control Center Operations, the Performance Analysis Group has responsibility for validating all committed Deep Space Network support to the various user projects. The group provides the Network with the analysis support necessary to assure that actual Network performance meets or exceeds committed levels throughout the mission. Validation is carried out as the signals are received in real time by monitoring the data streams and comparing the data quality against predicted values and established performance standards and tolerance limits. An important function is to generate the predictions used to point the antennas, acquire the radio frequency, and validate the monitored Network performance. Another function is anomaly investigation. An integral part of validation is the support task of generating and maintaining performance standards and tolerance limits for each flight project. The Performance Analysis Group is broadly divided into two subgroups: real-time personnel and nonreal-time personnel.

Bartok, C. D.↗
DOE OSTI2025

Radio Frequency Field Programable Gate Array Implementation of Reflectometry Cable Monitoring

PNNL has developed an innovative cable testing system that leverages the Xilinx RF System-on-Chip (RFSoC) technology to create a more flexible and capable measurement tool than traditional approaches. The architecture is designed on the ZCU111 development board and takes advantage of the high-speed digital to analog converters (DAC) and analog to digital converters (ADC) to generate and capture digitally synthesized waveforms. The platform allows engineers to easily adjust power, frequency, duration and modulation on the fly rather than being locked into fixed hardware configurations

Tedeschi, Jonathan [Pacific Northwest National Lab↗
NASA NTRS2017

Effects of the 2017 Solar Eclipse on HF Radio Propagation and the D-Region Ionosphere: Citizen Science Investigation

August 21, 2017 provided a unique opportunity to investigate the effects of the total solar eclipse on high frequency (HF) radio propagation and ionospheric variability. In Marshall Space Flight Center's partnership with the US Space and Rocket Center (USSRC) and Austin Peay State University (APSU), we engaged students and citizen scientists in an investigation of the eclipse effects on the mid-latitude ionosphere. Activities included implementing and configuring software, monitoring the HF Amateur Radio frequency bands and collecting radio transmission data on days before, the day of, and days after the eclipse to build a continuous record of changing propagation conditions as the moon's shadow marched across the United States. Post-eclipse radio propagation analysis provided insights into ionospheric variability due to the eclipse. We report on results, interpretation, and conclusions of these investigations.

Radio Propagatio↗
NASA NTRS1989

Very-Long-Baseline Interferometry Using Cheap Satellites

Celestial radiation below 25 MHz, heretofore inaccessible, yields new insights. Report discusses feasibility of array of small satellites deployed in high orbit around Earth to monitor celestial radio sources at frequencies less than 25 MHz. Objective to make high-angular-resolution map of such sources over entire sky by use of very-long-baseline interferometry (VLBI).

Mahoney, M. J.↗
NASA NTRS1992

The locator system for wandering individuals

Configurations and operation strategies are described for a wanderer locator system based on wireless radio frequency communication designed to monitor elderly patients who may wander beyond safe perimeters in the home or in an institutional setting. The modular components of this wandering notification system are (1) portable transmitter/receivers to be worn or carried by the patient and the caretaker, (2) detectors to be mounted in doorways or other perimeters of a safe area, (3) programmable central processing units to control, communicate with, and/or trace the portable and remote devices, and (4) a cathode ray tube that can display information on patient location or system status. Photographs of all system components and illustrations of operations concepts are included.

Davidson, Shayla↗
NASA NTRS2000

Field-Deployable Acoustic Digital Systems for Noise Measurement

Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for the first time in the field along with DAMS system for the Community Noise Flight Test using the NASA LaRC-757 aircraft during April, 2000. The test was performed at Airborne Airport in Wilmington, OH to validate predicted noise reduction benefits from alternative operational procedures. The test matrix was composed of various combinations of altitude, cutback power, and aircraft weight. The DAMS digitizes the acoustic inputs at the microphone site and can be located up to 2000 feet from the van which houses the acquisition, storage and analysis equipment. Digitized data from up to 10 microphones is recorded on a Jaz disk and is analyzed post-test by microcomputer system. The RASS digitizes and stores acoustic inputs at the microphone site that can be located up to three miles from the base station and can compose a 3 mile by 3 mile array of microphones. 16-bit digitized data from the microphones is stored on removable Jaz disk and is transferred through a high speed array to a very large high speed permanent storage device. Up to 30 microphones can be utilized in the array. System control and monitoring is accomplished via Radio Frequency (RF) link. This paper will present a detailed description of both systems, along with acoustic data analysis from both systems.

Shams, Qamar A.↗
NASA NTRS1986

Multifrequency observations of the superluminal quasar 3C 345

Attention is given to the continuum properties of the superluminal quasar 3C 345, on the basis of radio, optical, IR, and X-ray frequency monitorings, as well as by means of simultaneous multifrequency spectra extending from the radio through the X-ray bands. Radio outbursts, which appear to follow IR-optical outbursts by about one year, first occur at the highest frequencies, as expected from optical depth effects; the peak flux is nevertheless often reached at several frequencies at once. The beginning of outbursts, as defined by mm-measurements, corresponds to the appearance of the three known 'superluminal' components. An increase in the X-ray flux during 1979-1980 corresponds to increased radio flux, while the IR flux changes in the opposite sense.

Bregman, J. N.↗
DOE OSTI2021

A Frequency-Programmable Miniaturized Radio Frequency Transmitter for Animal Tracking

In animal tracking applications, smaller transmitters can reduce the impact of the transmitter on the tagged animal and thus provide more accurate data about animal behavior. By combining a novel circuit design and a newly developed micro-battery, we developed frequency-programmable and more powerful radio frequency transmitters that are about 40% smaller and lighter in weight than the smallest commercial counterpart for animal monitoring at the time of development. The new radio frequency transmitter has a miniaturized form factor for studying small animals. Designs of two coding schemes were developed: one transmits unmodulated signals (weight: 152 mg; dimensions: Ø 2.95 mm × 11.22 mm), and the other transmits modulated signals (weight: 160 mg; dimensions: Ø 2.95 mm × 11.85 mm). To accommodate different transmitter life requirements, each design can be configured to transmit in high or low signal strength. Prototypes of these transmitters were evaluated in the laboratory and exhibited comparable or longer service life and higher signal strength compared to their smallest commercial counterparts.

47 OTHER INSTRUMENTATION↗
NASA NTRS1988

Space Shuttle Main Engine radio frequency emissions

Several approaches to develop a diagnostics system for monitoring the operational health of the Space Shuttle Main Engine (SSME) are being evaluated. The ultimate goal is providing protection for the SSME as well as improving ground and flight test techniques. One scenario with some potential is measuring radio frequency (RF) emissions (if present) in the exhaust plume and correlating the data to engine health. An RF emissions detection system was therefore designed, the equipment leased, and the components integrated and checked out to conduct a quick-look investigation of RF emissions in the SSME exhaust plume. The system was installed on the A-1 Test Stand at Stennis Space Center, MS, and data were successfully acquired during SSME firings from May 3 to September 15, 1988. The experiments indicated that emitted radiation in the RF (20 to 470 MHz) spectrum definitely exists in the SSME exhaust plume, and is of such magnitude that it can be distinguished during the firing from background noise. Although additional efforts are necessary to assess the merit of this approach as a health monitoring technique, the potential is significant, and additional studies are recommended.

Rester, A. W.↗
NASA NTRS2008

An Analytical Model for the Prediction of a Micro-Dosimeter Response Function

A rapid analytical procedure for the prediction of a micro-dosimeter response function in low Earth orbit (LEO), correlated with the Space Transportation System (STS, shuttle) Tissue Equivalent Proportional Counter (TEPC) measurements is presented. The analytical model takes into consideration the energy loss straggling and chord length distribution of the detector, and is capable of predicting energy deposition fluctuations in a cylindrical micro-volume of arbitrary aspect ratio (height/diameter) by incoming ions through both direct and indirect (ray) events. At any designated (ray traced) target point within the vehicle, the model accepts the differential flux spectrum of Galactic Cosmic Rays (GCR) and/or trapped protons at LEO as input. On a desktop PC, the response function of TEPC for each ion in the GCR/trapped field is computed at the average rate of 30 seconds/ion. The ionizing radiation environment at LEO is represented by O'Neill fs GCR model (2004), covering charged particles in the 1 less than or equal to Z less than or equal to 28. O'Neill's free space GCR model is coupled with the Langley Research Center (LaRC) angular dependent geomagnetic cutoff model to compute the transmission coefficient in LEO. The trapped proton environment is represented by a LaRC developed time dependent procedure which couples the AP8MIN/AP8MAX, Deep River Neutron Monitor (DRNM) and F10.7 solar radio frequency measurements. The albedo neutron environment is represented by the extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. The charged particle transport calculations correlated with STS 51 and 114 flights are accomplished by using the most recent version (2005) of the LaRC deterministic High charge (Z) and Energy TRaNsport (HZETRN) code. We present the correlations between the TEPC model predictions (response function) and TEPC measured differential/integral spectra in the lineal energy (y) domain for both GCR and trapped protons, with the conclusion that the model correctly accounts for the increase in flux at low y values where energetic ions are the primary contributor. We further discuss that, even with the incorporation of angular dependency in the cutoffs, comparison of the GCR differential/integral flux between STS 51 and 114 TEPC measured data and current calculations indicates that there still exists an underestimation by the simulations at low to mid range y values. This underestimation is partly related the exclusion of the secondary pion particle production from the current version of HZETRN.

Badavi, Francis F.↗