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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Radiometric correction and equalization of satellite digital data

Satellite digital data from Landsat and NOAA satellites is often marred by striping or streaking errors due to variations in the response of the radiometric sensors. In this paper, we discuss the equalization of the digital data as a preprocessing step, prior to image enhancement or automatic classification. The methods described make use of statistics of the data itself to generate nonlinear or linear memory-less equalization algorithms. These algorithms, by contrast to multidimensional filtering, do not result in a loss of spatial resolution. Examples of applications to Landsat and NOAA-3 thermal infrared data are given and illustrated.

Algazi, V. R.↗
NASA NTRS1984

Detection of aspen/conifer forest mixes from multitemporal Landsat digital data

Aspen, conifer and mixed aspen/conifer forests were mapped for a 15-quadrangle study area in the Utah-Idaho Bear River Range using Landsat multispectral scanner data. Digital classification and statistical analysis of Landsat data allowed the identification of six groups of signatures which reflect different types of aspen/conifer forest mixing. Photo interpretations of the print symbols suggest that such classes are indicative of mid to late seral aspen forests. Digital print map overlayes and acreage calculations were prepared for the study area quadrangles. Further field verification is needed to acquire additional information about the nature of the forests. Single data Landsat analysis should be a cost effective means to index aspen forests which are at least in the mid seral phase of conifer invasion. Since aspen canopies tend to obscure understory conifers for early seral forests, a second data analysis, using data taken when aspens are leafless, could provide information about early seral aspen forests.

Merola, J. A.↗
NASA NTRS1982

Detection of aspen-conifer forest mixes from LANDSAT digital data

Aspen, conifer and mixed aspen/conifer forests were mapped for a 15-quadrangle study area in the Utah-Idaho Bear River Range using LANDSAT multispectral scanner data. Digital classification and statistical analysis of LANDSAT data allowed the identification of six groups of signatures which reflect different types of aspen/conifer forest mixing. Photo interpretations of the print symbols suggest that such classes are indicative of mid to late seral aspen forests. Digital print map overlays and acreage calculations were prepared for the study area quadrangles. Further field verification is needed to acquire additional information about the nature of the forests. Single date LANDSAT analysis should be a cost effective means to index aspen forests which are at least in the mid seral phase of conifer invasion. Since aspen canopies tend to obscure understory conifers for early seral forests, a second date analysis, using data taken when aspens are leafless, could provide information about early seral aspen forests.

Jaynes, R. A.↗
NASA NTRS1975

University of Utah (Wallops) precision meteorological data digitizer

The data digitizing system takes pulsed signals from meteorological rocket sondes and radiosondes and converts the information (the time interval between pulses) into a digital form for magnetic recording and further processing by digital computer. The basic digitizer configuration contains a master sequencer that allows for data storage and release in an accumulator. Thus, the digitizer provides for convenient interfacing in real time monitoring.

Staffanson, F. L.↗
NASA NTRS1977

Urban area delineation and detection of change along the urban-rural boundary as derived from LANDSAT digital data

LANDSAT digital multispectral scanner data, in conjunction with supporting ground truth, were investigated to determine their utility in delineation of urban-rural boundaries. The digital data for the metropolitan areas of Washington, D. C.; Austin, Texas; and Seattle, Washingtion; were processed using an interactive image processing system. Processing focused on identification of major land cover types typical of the zone of transition from urban to rural landscape, and definition of their spectral signatures. Census tract boundaries were input into the interactive image processing system along with the LANDSAT single and overlayed multiple date MSS data. Results of this investigation indicate that satellite collected information has a practical application to the problem of urban area delineation and to change detection.

Christenson, J. W.↗
NASA NTRS1992

Matrix error correction for digital data

A technique for digital data error detection and correction is disclosed which adds alignment and checksum bytes to three sides of a matrix (24) of digital data to be protected. This technique is particularly used for the recording and storage (16,18) of digital data on video tape medium (14). The digital data is treated as a matrix block (24). Checksum and alignment bytes are added (20) to the digital data before tape storage and stripped (22) therefrom after successful alignment checks and data validation. In particular, the first column may be used to provide alignment bytes of a predetermined value for each row. The last column provides row checksum bytes for the data in each row. The last row provides column check sum bytes for each column, excluding the column of alignment bytes. The data location at the intersection of the row of column checksum bytes and the column of row checksum bytes may be used as a checksum byte for either the row or column checksum bytes.

Dotson, Ronald S.↗
NASA NTRS1991

Three-dimensional displays for natural hazards analysis, using classified Landsat Thematic Mapper digital data and large-scale digital elevation models

Methods are described for using Landsat Thematic Mapper digital data and digital elevation models for the display of natural hazard sites in a mountainous region of northwestern Montana, USA. Hazard zones can be easily identified on the three-dimensional images. Proximity of facilities such as highways and building locations to hazard sites can also be easily displayed. A temporal sequence of Landsat TM (or similar) satellite data sets could also be used to display landscape changes associated with dynamic natural hazard processes.

Butler, David R.↗
DOE OSTI2026

Fermilab PIP-II machine protection system digitized data noise elimination scheme and its FPGA implementation

In Fermilab's PIP-II machine protection system, beam loss signals from various detectors are digitized at 125 MS/s. Noise from both high-frequency sources and low-frequency 60 Hz AC power equipment can contaminate the data. To suppress noise across these ranges—especially 60 Hz and its harmonics, which overlap with beam loss signal frequencies—advanced digital processing beyond standard filtering is required. Several real-time functional blocks were simulated and tested on an FPGA: (1) a dual time-constant discharging integrator filter, (2) a de-ripple baseline extraction and storage block, and (3) a fast-recovery discharging integrator. The nonlinear IIR integrator filter removes high-frequency noise and feeds into the baseline extractor. Upon detecting abrupt beam loss, it switches to a longer time constant to prevent baseline distortion. The de-ripple block calculates a valid baseline by averaging over multiple 60 Hz periods, storing results in a 4096-word FPGA RAM. This baseline is subtracted from raw data before integration by the fast-recovery block, which resets quickly after use. All blocks achieved expected performance and were successfully implemented on a low-cost FPGA.

Wu, Jinyuan [Fermilab]↗
NASA NTRS1988

An operations manual for the digital data system

The Digital Data System (DDS) was designed to incorporate the analog-to-digital conversion process into the initial data acquisition stage and to store the data in a digital format. This conversion is done as part of the acquisition process. Consequently, the data are ready to be analyzed as soon as the test is completed. This capability permits the researcher to alter test parameters during the course of the experiment based on the information acquired in a prior portion of the test. The DDS is currently able to simultaneously acquire up to 10 channels of data. The purpose of this document is fourfold: (1) to describe the capabilities of the hardware in sufficient detail to allow the reader to determine whether the DDS is the optimum system for a particular experiment; (2) to present some of the more significant software developed to provide analyses within a short time of the completion of data acquisition; (3) to provide the reader with sample runs of major software routines to demonstrate their convenience and simple usage; and (4) a portion of the document is used to describe software which uses an FFT-box to provide a means of comparison against which the DDS can be checked.

Jones, Michael G.↗
NASA NTRS1992

Digital data acquisition and preliminary instrumentation study for the F-16 laminar flow control vehicle

Preliminary studies have shown that maintenance of laminar flow through active boundary-layer control is viable. Current research activity at NASA Langley and NASA Dryden is utilizing the F-16XL-1 research vehicle fitted with a laminar-flow suction glove that is connected to a vacuum manifold in order to create and control laminar flow at supersonic flight speeds. This experimental program has been designed to establish the feasibility of obtaining laminar flow at supersonic speeds with highly swept wing and to provide data for computational fluid dynamics (CFD) code calibration. Flight experiments conducted as supersonic speeds have indicated that it is possible to achieve laminar flow under controlled suction at flight Mach numbers greater than 1. Currently this glove is fitted with a series of pressure belts and flush mounted hot film sensors for the purpose of determining the pressure distributions and the extent of laminar flow region past the stagnation point. The present mode of data acquisition relies on out-dated on board multi-channel FM analogue tape recorder system. At the end of each flight, the analogue data is digitized through a long laborious process and then analyzed. It is proposed to replace this outdated system with an on board state-of-the-art digital data acquisition system capable of a through put rate of up to 1 MegaHertz. The purpose of this study was three-fold: (1) to develop a simple algorithm for acquiring data via 2 analogue-to-digital convertor boards simultaneously (total of 32 channels); (2) to interface hot-film/wire anemometry instrumentation with a PCAT type computer; and (3) to characterize the frequency response of a flush mounted film sensor. A brief description of each of the above tasks along with recommendations are given.

Ostowari, Cyrus↗
NASA NTRS1984

Classification of vegetation communities in the Battle Mountain SE quadrangle, Nevada with MSS digital data

LANDSAT MSS digital data were utilized to identify vegetation types in an area of Battle Mountain SE in northern Nevada. Ways in which terrain data may improve spectral classification were investigated. The basic data set was a CCT of LANDSAT scene 82233617450, dated 15 June 1981. Seventeen ecotypic classifications were identified in the study area on the basis of field investigations. The percent cover by life form and non-living material for the 17 classes is summarized along with the percent cover by species for the 17 classes.

Ridd, M. K.↗
NASA NTRS1994

Stand-alone digital data storage control system including user control interface

A storage control system includes an apparatus and method for user control of a storage interface to operate a storage medium to store data obtained by a real-time data acquisition system. Digital data received in serial format from the data acquisition system is first converted to a parallel format and then provided to the storage interface. The operation of the storage interface is controlled in accordance with instructions based on user control input from a user. Also, a user status output is displayed in accordance with storage data obtained from the storage interface. By allowing the user to control and monitor the operation of the storage interface, a stand-alone, user-controllable data storage system is provided for storing the digital data obtained by a real-time data acquisition system.

Wright, Kenneth D.↗
NASA NTRS1974

Correlation between cloud thickness and brightness using Nimbus 4 THIR data /11.5-micron channel/ and ATS 3 digital data

Nimbus 4 data (11.5-micron) channel and ATS 3 digitized data were analyzed for three days during April and May 1970. Cloud-top temperature, as measured by the 11.5-micron channel of the satellite radiometer, shows a close negative correlation with cloud brightness measured by the ATS 3 satellite. This is especially true in well-developed cumulonimbus clouds. An estimate of cloud heights corresponding to cloud-top temperature was obtained by using radiosonde data and radar images, and the relationships between the cloud thickness and brightness counts were derived for the cumulonimbus clouds.

Park, S.-U.↗
NASA NTRS1983

Detection of aspen/conifer forest mixes from multitemporal LANDSAT digital data

Aspen, conifer and mixed aspen/conifer forests were mapped for a 15-quadrangle study area in the Utah-Idaho Bear River Range using LANDSAT multispectral scanner (MSS) data. The digital MSS data were utilized to devise quantitative indices which correlate with apparently stable and seral aspen forests. The extent to which a two-date LANDSAT MSS analysis may permit the delineation of different categories of aspen/conifer forest mix was explored. Multitemporal analyses of MSS data led to the identification of early, early to mid, mid to late, and late seral stages of aspen/conifer forest mixing.

Merola, J. A.↗
NASA NTRS1991

High Density Digital Data Storage System

The High Density Digital Data Storage System was designed to provide a cost effective means for storing real-time data from the field-deployable digital acoustic measurement system. However, the high density data storage system is a standalone system that could provide a storage solution for many other real time data acquisition applications. The storage system has inputs for up to 20 channels of 16-bit digital data. The high density tape recorders presently being used in the storage system are capable of storing over 5 gigabytes of data at overall transfer rates of 500 kilobytes per second. However, through the use of data compression techniques the system storage capacity and transfer rate can be doubled. Two tape recorders have been incorporated into the storage system to produce a backup tape of data in real-time. An analog output is provided for each data channel as a means of monitoring the data as it is being recorded.

Wright, Kenneth D., II↗