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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

GLobal Integrated Design Environment

The GLobal Integrated Design Environment (GLIDE) is a collaborative engineering application built to resolve the design session issues of real-time passing of data between multiple discipline experts in a collaborative environment. Utilizing Web protocols and multiple programming languages, GLIDE allows engineers to use the applications to which they are accustomed in this case, Excel to send and receive datasets via the Internet to a database-driven Web server. Traditionally, a collaborative design session consists of one or more engineers representing each discipline meeting together in a single location. The discipline leads exchange parameters and iterate through their respective processes to converge on an acceptable dataset. In cases in which the engineers are unable to meet, their parameters are passed via e-mail, telephone, facsimile, or even postal mail. The result of this slow process of data exchange would elongate a design session to weeks or even months. While the iterative process remains in place, software can now exchange parameters securely and efficiently, while at the same time allowing for much more information about a design session to be made available. GLIDE is written in a compilation of several programming languages, including REALbasic, PHP, and Microsoft Visual Basic. GLIDE client installers are available to download for both Microsoft Windows and Macintosh systems. The GLIDE client software is compatible with Microsoft Excel 2000 or later on Windows systems, and with Microsoft Excel X or later on Macintosh systems. GLIDE follows the Client-Server paradigm, transferring encrypted and compressed data via standard Web protocols. Currently, the engineers use Excel as a front end to the GLIDE Client, as many of their custom tools run in Excel.

Kunkel, Matthew↗
NASA NTRS2012

Interuser Interference Analysis for Direct-Sequence Spread-Spectrum Systems Part I: Partial-Period Cross-Correlation

This presentation discusses an analysis approach to evaluate the interuser interference for Direct-Sequence Spread-Spectrum (DSSS) Systems for Space Network (SN) Users. Part I of this analysis shows that the correlation property of pseudo noise (PN) sequences is the critical factor which determines the interuser interference performance of the DSSS system. For non-standard DSSS systems in which PN sequence s period is much larger than one data symbol duration, it is the partial-period cross-correlation that determines the system performance. This study reveals through an example that a well-designed PN sequence set (e.g. Gold Sequence, in which the cross-correlation for a whole-period is well controlled) may have non-controlled partial-period cross-correlation which could cause severe interuser interference for a DSSS system. Since the analytical derivation of performance metric (bit error rate or signal-to-noise ratio) based on partial-period cross-correlation is prohibitive, the performance degradation due to partial-period cross-correlation will be evaluated using simulation in Part II of this analysis in the future.

Ni, Jianjun (David)↗
NASA NTRS2011

C/NOFS Measurements of Magnetic Perturbations in the Low-Latitude Ionosphere During Magnetic Storms

The Vector Electric Field Investigation suite on the C/NOFS satellite includes a fluxgate magnetometer to monitor the Earth s magnetic fields in the low-latitude ionosphere. Measurements yield full magnetic vectors every second over the range of +/-45,000 nT with a one-bit resolution of 1.37 nT (16 bit A/D) in each component. The sensor s primary responsibility is to support calculations of both V x B and E x B with greater accuracy than can be obtained using standard magnetic field models. The data also contain information about large-scale current systems that, when analyzed in conjunction with electric field measurements, promise to significantly expand understanding of equatorial electrodynamics. We first compare in situ measurements with the POMME (Potsdam Magnetic Model of the Earth) model to establish in-flight sensor "calibrations" and to compute magnetic residuals. At low latitudes the residuals are predominately products of the storm time ring current. Since C/NOFS provides a complete coverage of all local times every 97 min, magnetic field data allow studies of the temporal evolution and local time variations of storm time ring current. The analysis demonstrates the feasibility of using instrumented spacecraft in low-inclination orbits to extract a timely proxy for the provisional Dst index and to specify the ring current s evolution.

Le, Guan↗
NASA NTRS2012

C/NOFS Measurements of Stormtime Magnetic Perturbations in the Low-latitude Ionosphere

The Vector Electric Field Investigation suite on the C/NOFS satellite includes a fluxgate magnetometer to monitor the Earth's magnetic fields in the low-latitude ionosphere. Measurements yield full magnetic vectors every second over the range of +/- 45,000 nT with a one-bit resolution of 1.37 nT (16 bit AID) in each component. The sensor's primary responsibility is to support calculations of both VxB and ExB with greater accuracy than can be obtained using standard magnetic field models. The data also contain information about large-scale current systems, that, when analyzed in conjunction with electric field measurements, promise to significantly expand understanding of equatorial electrodynamics. We first compare in situ measurements with the POMME (POtsdam Magnetic Model of the Earth) model to establish in-flight sensor "calibrations" and to compute magnetic residuals. At low latitudes the residuals are predominately products of the stormtime ring current. Since C/NOFS provides a complete coverage of all local times every 97 minutes, magnetic field data allow studies of the temporal evolution and local-time variations of stormtime ring current. The analysis demonstrates the feasibility of using instrumented spacecraft in low-inclination orbits to extract a timely proxy for the provisional Dst index and to specify the ring current's evolution.

Le, Guan↗
NASA NTRS2019

Monitoring Volcanic Eruptions by OMI/OMPS, ASTER, and MERRA-2

Volcanic lava flows and/or the gas eruptions are the most common characteristics that can be remotely monitored with satellite technology in the global perspective and on different timescales. Atmospheric Sulfur Dioxide (SO2), one of the most abundant gases from volcanic eruptions apart from atmospheric common gases Carbon Dioxide and water vapor, can be directly detected by space-based sensors on satellites. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is one of the 12 Distributed Active Archive Centers (DAACs) within NASA's Earth Observing System Data and Information System (EOSDIS), which archives SO2 data sets from the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) in 1978, till the ongoing Ozone Monitoring Instrument (OMI) on NASA's EOS-Aura satellite, the Ozone Mapping Profiler Suite (OMPS) Nadir Mapper (NM) on both the Suomi National Polar-Orbiting Partnership (Suomi-NPP or SNPP) and the Joint Polar-orbiting Satellite System-1 (JPSS-1) satellites, into the future JPSS missions. In addition to the standard OMI/Aura and OMPS/S-NPP SO2 products, SO2 products created under the charter of the Making Earth System Data Records for Use in Research Environments (MEaSUREs) project, are also archived at GES DISC, through which NASA enacts to expand understanding the Earth system using consistent data records. The Land Processes Distributed Active Archive Center (LP DAAC) is another EOSDIS's DAAC that provides land data products and operates as a partnership with the U.S. Geological Survey (USGS). The LP DAAC has been archiving the satellite imagery from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's EOS-Terra satellite, a high spatial resolution (15 meters) and 14 band multispectral instrument. The ASTER imagery is one of the land products contributing to the application for monitoring hot spots and land terrain changes caused by volcanic eruption events. The data potential in GES DISC and LP DAAC to monitor volcanic sources of SO2 and the influence of wind fields on the gas plume spread will be demonstrated with the most recent 2018 May-July Kilauea Volcano eruption.

Zeng, Jian↗
NASA NTRS1993

TransFit: Finite element analysis data fitting software

The Advanced X-Ray Astrophysics Facility (AXAF) mission support team has made extensive use of geometric ray tracing to analyze the performance of AXAF developmental and flight optics. One important aspect of this performance modeling is the incorporation of finite element analysis (FEA) data into the surface deformations of the optical elements. TransFit is software designed for the fitting of FEA data of Wolter I optical surface distortions with a continuous surface description which can then be used by SAO's analytic ray tracing software, currently OSAC (Optical Surface Analysis Code). The improved capabilities of Transfit over previous methods include bicubic spline fitting of FEA data to accommodate higher spatial frequency distortions, fitted data visualization for assessing the quality of fit, the ability to accommodate input data from three FEA codes plus other standard formats, and options for alignment of the model coordinate system with the ray trace coordinate system. TransFit uses the AnswerGarden graphical user interface (GUI) to edit input parameters and then access routines written in PV-WAVE, C, and FORTRAN to allow the user to interactively create, evaluate, and modify the fit. The topics covered include an introduction to TransFit: requirements, designs philosophy, and implementation; design specifics: modules, parameters, fitting algorithms, and data displays; a procedural example; verification of performance; future work; and appendices on online help and ray trace results of the verification section.

Freeman, Mark↗
NASA NTRS1996

Classification and designation systems for materials: A report on the present situation, an inventory of the systems in use, and comments on the future possibilities

The different systems that are in use for the major classes of engineering materials are summarized. The work was carried out within the scope of the Versailles project on advanced materials and standards (VAMAS). An inventory of national and international standards that give specifications for the materials and international standards are included. Comments on the increasing knowledge of, and the increasing demand for, data concerning the materials performance are included. Recommendations for future activities in the standardization of classification and designation systems are given.

Reynard, Keith W.↗
NASA NTRS1968

Digital data averager improves conventional measurement system performance

Multipurpose digital averager provides measurement improvement in noisy signal environments. It provides increased measurement accuracy and resolution to basic instrumentation devices by an arithmetical process in real time. It is used with standard conventional measurement equipment and digital data printers.

Naylor, T. K.↗
NASA NTRS1994

Time synchronized video systems

The idea of synchronizing multiple video recordings to some type of 'range' time has been tried to varying degrees of success in the past. Combining this requirement with existing time code standards (SMPTE) and the new innovations in desktop multimedia however, have afforded an opportunity to increase the flexibility and usefulness of such efforts without adding costs over the traditional data recording and reduction systems. The concept described can use IRIG, GPS or a battery backed internal clock as the master time source. By converting that time source to Vertical Interval Time Code or Longitudinal Time Code, both in accordance with the SMPTE standards, the user will obtain a tape that contains machine/computer readable time code suitable for use with editing equipment that is available off-the-shelf. Accuracy on playback is then determined by the playback system chosen by the user. Accuracies of +/- 2 frames are common among inexpensive systems and complete frame accuracy is more a matter of the users' budget than the capability of the recording system.

Burnett, Ron↗
NASA NTRS2010

The First Experiment with VLBI-GPS Hybrid System

In this paper, we introduce our GPS-VLBI hybrid system and show the results of the first experiment which is now under way. In this hybrid system, GPS signals are captured by a normal GPS antenna, down-converted to IF signals, and then sampled by the VLBI sampler VSSP32 developed by NICT. The sampled GPS data are recorded and correlated in the same way as VLBI observation data. The correlator outputs are the group delay and the delay rate. Since the whole system uses the same frequency standard, many sources of systematic errors are common between the VLBI system and the GPS system. In this hybrid system, the GPS antenna can be regarded as an additional VLBI antenna having multiple beams towards GPS satellites. Therefore, we expect that this approach will provide enough data to improve zenith delay estimates and geodetic results.

Kwak, Younghee↗
NASA NTRS1988

Transferring data objects: A focused Ada investigation

The use of the Ada language does not guarantee that data objects will be in the same form or have the same value after they have been stored or transferred to another system. There are too many possible variables in such things as the formats used and other protocol conditions. Differences may occur at many different levels of support. These include program level, object level, application level, and system level. A standard language is only one aspect of making a complex system completely homogeneous. Many components must be standardized and the various standards must be integrated. The principal issues in providing for interaction between systems are of exchanging files and data objects between systems which may not be compatible in terms of their host computer, operating system or other factors. A typical resolution of the problem of invalidating data involves at least a common external form, for data objects and for representing the relationships and attributes of data collections. Some of the issues dealing with the transfer of data are listed and consideration is given on how these issues may be handled in the Ada language.

Legrand, Sue↗
NASA NTRS1996

Modular Software for Spacecraft Navigation Using the Global Positioning System (GPS)

The Goddard Space Flight Center Flight Dynamics and Mission Operations Divisions have jointly investigated the feasibility of engineering modular Global Positioning SYSTEM (GPS) navigation software to support both real time flight and ground postprocessing configurations. The goals of this effort are to define standard GPS data interfaces and to engineer standard, reusable navigation software components that can be used to build a broad range of GPS navigation support applications. The paper discusses the GPS modular software (GMOD) system and operations concepts, major requirements, candidate software architecture, feasibility assessment and recommended software interface standards. In additon, ongoing efforts to broaden the scope of the initial study and to develop modular software to support autonomous navigation using GPS are addressed,

Truong, S. H.↗
NASA NTRS1995

Geophysical data analysis and visualization using the Grid Analysis and Display System

Several problems posed by the rapidly growing volume of geophysical data are described, and a selected set of existing solutions to these problems is outlined. A recently developed desktop software tool called the Grid Analysis and Display System (GrADS) is presented. The GrADS' user interface is a natural extension of the standard procedures scientists apply to their geophysical data analysis problems. The basic GrADS operations have defaults that naturally map to data analysis actions, and there is a programmable interface for customizing data access and manipulation. The fundamental concept of the GrADS' dimension environment, which defines both the space in which the geophysical data reside and the 'slice' of data which is being analyzed at a given time, is expressed The GrADS' data storage and access model is described. An argument is made in favor of describable data formats rather than standard data formats. The manner in which GrADS users may perform operations on their data and display the results is also described. It is argued that two-dimensional graphics provides a powerful quantitative data analysis tool whose value is underestimated in the current development environment which emphasizes three dimensional structure modeling.

Doty, Brian E.↗
NASA NTRS1991

Weighted slit extraction of low-dispersion IUE spectral data

The weighted slit extraction has been chosen by the IUE project as the standard extraction for low-dispersion spectra in the final IUE archives. In order to properly weight the data within the extraction slit and obtain the optimal evaluation of the true spectrum, a noise model is derived for IUE data. The exclusion of cosmic rays is demonstrated and the improvement in signal-to-noise ratio is quantified for spectra taken with a wide range of flux level. Problematic spectra, such as trailed spectra, multiple spectra, discontinuous spectra, and emission-line spectra, are extracted to demonstrate the robust nature of the method. Comparisons are made between the standard IUE Standard Image Processing System (IUESIPS) extraction, nonstandard narrow slit extraction, trailed IUESIPS extraction, and weighted extraction for these data. Other weighted slit extractions are briefly discussed. The advantages of the weighted slit extraction are: (1) the extraction improves the signal-to-noise ratio of the spectrum while conserving total flux; (2) most of the cosmic rays are automatically removed; (3) the output includes an error estimate for each point in the flux spectrum; and (4) the algorithm can be run in a batch mode that requires no special input parameters.

Kinney, A. L.↗
NASA NTRS2024

Standard Operating Procedure (SOP) for Flight Testing a Radiosonde and 3D Sonic Anemometer Configuration on a Multi-rotor Uninhabited Aerial System (UAS)

The purpose of this Standard Operating Procedure (SOP) is to establish a uniform procedure for initialization of a radiosonde, a 3D sonic anemometer, and collection of sounding data with correct sensor integration via a multi-rotor uninhabited aerial system (UAS) within the Langley Research Center’s (LaRC) Uninhabited Aerial System Operations Office (UASOO).

Tyler L. Willhite↗
NASA NTRS2003

A Study on the Development of Service Quality Index for Incheon International Airport

The main purpose of this study is located at developing Ominibus Monitors System(OMS) for internal management, which will enable to establish standards, finding out matters to be improved, and appreciation for its treatment in a systematic way. It is through developing subjective or objective estimation tool with use importance, perceived level, and complex index at international airport by each principal service items. The direction of this study came towards for the purpose of developing a metric analysis tool, utilizing the Quantitative Second Data, Analysing Perceived Data through airport user surveys, systemizing the data collection-input-analysis process, making data image according to graph of results, planning Service Encounter and endowing control attribution, and ensuring competitiveness at the minimal international standards. It is much important to set up a pre-investigation plan on the base of existent foreign literature and actual inspection to international airport. Two tasks have been executed together on the base of this pre-investigation; one is developing subjective estimation standards for departing party, entering party, and airport residence and the other is developing objective standards as complementary methods. The study has processed for the purpose of monitoring services at airports regularly and irregularly through developing software system for operating standards after ensuring credibility and feasibility of estimation standards with substantial and statistical way.

Lee, Kang Seok↗
NASA NTRS2002

Newly Enacted Intent Changes to ADS-B MASPS: Emphasis on Operations, Compatibility, and Integrity

Significant changes to the intent reporting structure in the Minimum Aviation System Performance Standards (MASPS) for Automatic Dependent Surveillance Broadcast (ADS-B) have recently been approved by RTCA Special Committee 186. The re-structured intent formats incorporate two major changes to the current MASPS (DO-242): addition of a Target State (TS) report that provides information on the horizontal and vertical targets for the current flight segment and replacement of the current Trajectory Change Point (TCP) and TCP+1 reports with Trajectory Change (TC) reports. TC reports include expanded information about TCPs and their connecting flight segments, in addition to making provisions for trajectory conformance elements. New intent elements are designed to accommodate a greater range of intent information, better reflect operational use and capabilities of existing and future aircraft avionics, and aid trajectory synthesis and conformance monitoring systems. These elements are expected to benefit near-term and future Air Traffic Management (ATM) applications, including separation assurance, local traffic flow management, and conformance monitoring. The current MASPS revision (DO-242A) implements those intent elements that are supported by current avionics standards and data buses. Additional elements are provisioned for inclusion in future MASPS revisions (beyond DO-242A) as avionics systems are evolved.

Barhydt, Richard↗
NASA NTRS1994

Decoder synchronization for deep space missions

The Consultative Committee for Space Data Standards (CCSDS) recommends that space communication links employ a concatenated, error-correcting, channel-coding system in which the inner code is a convolutional (7,1/2) code and the outer code is a (255,223) Reed-Solomon code. The traditional implementation is to perform the node synchronization for the Viterbi decoder and the frame synchronization for the Reed-Solomon decoder as separate, sequential operations. This article discusses a unified synchronization technique that is required for deep space missions that have data rates and signal-to-noise ratios (SNR's) that are extremely low. This technique combines frame synchronization in the bit and symbol domains and traditional accumulated-metric growth techniques to establish a joint frame and node synchronization. A variation on this technique is used for the Galileo spacecraft on its Jupiter-bound mission.

Statman, J. I.↗