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At least 109 records · Page 6

Moire patterns and two-dimensional aliasing in line scanner data acquisition systems

The basic mechanism underlying the generation of Moire patterns in line scanner data acquisition systems is examined. A general expression is developed in terms of typical system parameters for the reproduced image of such systems and the interaction of the image spectrum; the raster frequency and digital sampling frequency of the A/D conversion process are discussed and examples given. System design requirements for avoiding Moire pattern generation and two-dimensional aliasing are discussed.

Mcgillem, C. D.↗

Laser velocimeter data acquisition system for the Langley 14- by 22-foot subsonic tunnel. Software reference guide version 3.3

The Laser Velocimeter Data Acquisition System (LVDAS) in the Langley 14- by 22-Foot Tunnel is controlled by a comprehensive software package. The software package was designed to control the data acquisition process during wind tunnel tests which employ a laser velocimeter measurement system. This report provides detailed explanations on how to configure and operate the LVDAS system to acquire laser velocimeter and static wind tunnel data.

Jumper, Judith K.↗

A multiband radiometer and data acquisition system for remote sensing field research

Specifications are described for a recently developed prototype multispectral data acquisition system which consists of multiband radiometer with 8 bands between 0.4 and 12.5 micrometers and a data recording module to record data from the radometer and ancillary sources. The systems is adaptable to helicopter, truck, or tripod platforms, as well as hand-held operation. The general characteristics are: (1) comparatively inexpensive to acquire, maintain and operate; (2) simple to operate and calibrate; (3) complete with data hardware and software; and (4) well documented for use by researchers. The instrument system is to be commercially available and can be utilized by many researchers to obtain large numbers of accurate, calibrated spectral measurements. It can be a key element in improving and advancing the capability for field research in remote sensing.

Bauer, M. E.↗

Rotor fatigue monitoring data acquisition system

The 40 by 80 Foot Wind Tunnel of the National Full Scale Aerodynamics Complex (NFAC) had a requirement to monitor rotor fatigue during a test. This test subjected various rotor components to stress levels higher than their structural fatigue limits. A data acquisition system was developed to monitor the cumulative fatigue damage of rotor components using National Instruments hardware and LabVIEW software. A full description of the data acquisition system including its configuration and salient features, is presented in this paper.

Smith, Scott M.↗

Upgrades to Common Data Acquisition System Software Development for NASA's Rocket Propulsion Test Facilities and Software Reuse

Approximately five years ago, the National Aeronautics and Space Administration (NASA) Stennis Space Center (SSC) resumed operation of its large rocket engine test facilities after thirty years of contractor control. During this period, contactors used their own proprietary Data Acquisition System (DAS) to record and process rocket propulsion test data. The transition from a contractor managed facility to a NASA managed facility posed a difficult challenge. In order to support the commercial space launch initiative, SSC needed to develop a software replacement for the contractor proprietary DAS. This replacement software would enable SSC to operate propulsion test facilities more cost effectively and to be more readily able to adapt software for reuse, while at the same time provide internal and external customers with reliable population test data. Therefore, SSC developed in-house, a non-proprietary software suite of applications to replace the previously used proprietary DAS. The requirements for the DAS suite included recording and processing propulsion test data. This capability eliminates the necessity for customers to provide a DAS or rely on a competitor's DAS. An additional benefit of owning the software suite included enabling the ability to add additional features and functionality at a lower cost. The Rocket Propulsion Test (RPT) Program Office reviewed consideration for funding this project with the caveat that development of the software included availability for use with minimal modifications to all SSC test facilities and RPT centers: Marshall Space Flight Center (MSFC), White Sands Test Facility (WSTF), and Glenn Research Center (GRC) Plum Brook Station. Based upon this guideline, SSC created the NASA Data Acquisition System (NDAS) software suite. The ability to use the software at multiple centers, even though each field center uses differing DAS hardware with different capabilities, drove a requirement that the software design be portable with minimal modifications to the software. Then, with software release requirements, evaluations, and approvals completed, the NDAS software suite could also become available to other government agencies, corporations, universities, and the general United States public.

Herbert, Phillip W., Sr.↗

Development and operation of a real-time data acquisition system for the NASA, Langley Research Center Differential Absorption Lidar

The capabilities of the DIAL data acquisition system (DAS) for the remote measurement of atmospheric trace gas concentrations from ground and aircraft platforms were extended through the purchase and integration of other hardware and the implementation of improved software. An operational manual for the current system is presented. Hardware and peripheral device registers are outlined only as an aid in debugging any DAS problems which may arise.

Butler, C.↗

Real-time data acquisition system for the NASA Langley transonic dynamics tunnel

The hardware configuration of the Transonic Dynamics Wind Tunnel Data Acquisition System (DAS) which consists of an analog front end that can process up to 260 channels of data is presented. The DAS also has a multi-channel analog-to-digital subsystem that can process up to 50,000 samples of data per sec, and a digital computer with standard and nonstandard devices, with graphics capability. The software configuration of the DAS and complex hardware/software interfaces are described, which can provide automatic amplifier gain and offset adjustment for each data channel. Finally, a summary of specific DAS applications is given including the real-time processing of dynamic deflection data, unsteady pressure measurements, and flutter and buffet data.

Cole, P. H.↗

Advanced Data Acquisition Systems with Self-Healing Circuitry

Kennedy Space Center's Spaceport Engineering & Technology Directorate has developed a data acquisition system that will help drive down the cost of ground launch operations. This system automates both the physical measurement set-up function as well as configuration management documentation. The key element of the system is a self-configuring, self-calibrating, signal-conditioning amplifier that automatically adapts to any sensor to which it is connected. This paper will describe the core technology behind this device and the automated data system in which it has been integrated. The paper will also describe the revolutionary enhancements that are planned for this innovative measurement technology. All measurement electronics devices contain circuitry that, if it fails or degrades, requires the unit to be replaced, adding to the cost of operations. Kennedy Space Center is now developing analog circuits that will be able to detect their own failure and dynamically reconfigure their circuitry to restore themselves to normal operation. This technology will have wide ranging application in all electronic devices used in space and ground systems.

Larson, William E.↗

Programmable Digital Baud Integrators for the Radar High-speed Data Acquisition System

An all-digital technique for the Baud Integrators of the Radar High-Speed Data Acquisition system, a technique that avoids the inherent problems associated with analog systems such as the need for calibration and adjustment is described. The integration period of this system is selectable in 100-ns steps from 100 ns to 3276700 ns.

Farazian, K. H.↗

NASA Data Acquisitions System (NDAS) Software Architecture

The NDAS Software Project is for the development of common low speed data acquisition system software to support NASA's rocket propulsion testing facilities at John C. Stennis Space Center (SSC), White Sands Test Facility (WSTF), Plum Brook Station (PBS), and Marshall Space Flight Center (MSFC).

Davis, Dawn↗

CCD data acquisition systems at Lick and Keck Observatories

This paper will describe and compare two distinct but related CCD data acquisition systems (DAS) currently under development at Lick and Keck Observatories. Although these two systems have a number of major architectural differences, they share a considerable amount of common hardware and software. Both of these new systems build on a large body of proven software that is the foundation of the existing CCD DAS currently in use at Lick Observatory. Both will provide support for reading up to four on-chip amplifiers per CCD and/or reading out mosaics of CCD chips. In addition, they will provide the capability for interactive, real-time adjustment of CCD waveforms for engineering purposes. Each of these two systems is composed of three major subsystems: (1) an instrument computer and its software; (2) a data capture computer and its software; and (3) a CCD/dewar controller and its software. The instrument computer is a Unix workstation, and the functions it provides include user interfaces, the interactive real-time display of CCD images, and the recording of image and FITS header data to disk and/or tape. The data capture computer is responsible for the packaging and high-speed transfer of the CCD pixel data stream into a bulk RAM, and the subsequent transfer of this data to the instrument computer. The CCD/dewar controller generates the waveforms for clocking the CCD, digitizes the pixel data, and transmits it via high-speed link to the data capture computer. It is also responsible for monitoring and controlling the dewar temperature and cryogen levels. Given the number of different types of processors and high-speed data links employed in both systems, a major emphasis of this paper will be on the various forms of interprocessor communications utilized for data transfer and distributed process synchronization.

Kibrick, R. I.↗

A high speed data acquisition system for the analysis of velocity, density, and total temperature fluctuations at transonic speeds

The use of a high-speed Dynamic Data Acquisition System (DDAS) to measure simultaneously velocity, density, and total temperature fluctuations is described. The DDAS is used to automate the acquisition of hot-wire calibration data. The data acquisition, data handling, and data reporting techiques used by DDAS are described. Sample data are used to compare results obtained with the DDAS with those obtained from the FM tape and post-test digitization method.

Clukey, Steven J.↗

Real-Time Wireless Data Acquisition System

Current and future aerospace requirements demand the creation of a new breed of sensing devices, with emphasis on reduced weight, power consumption, and physical size. This new generation of sensors must possess a high degree of intelligence to provide critical data efficiently and in real-time. Intelligence will include self-calibration, self-health assessment, and pre-processing of raw data at the sensor level. Most of these features are already incorporated in the Wireless Sensors Network (SensorNet(TradeMark)), developed by the Instrumentation Group at Kennedy Space Center (KSC). A system based on the SensorNet(TradeMark) architecture consists of data collection point(s) called Central Stations (CS) and intelligent sensors called Remote Stations (RS) where one or more CSs can be accommodated depending on the specific application. The CS's major function is to establish communications with the Remote Stations and to poll each RS for data and health information. The CS also collects, stores and distributes these data to the appropriate systems requiring the information. The system has the ability to perform point-to-point, multi-point and relay mode communications with an autonomous self-diagnosis of each communications link. Upon detection of a communication failure, the system automatically reconfigures to establish new communication paths. These communication paths are automatically and autonomously selected as the best paths by the system based on the existing operating environment. The data acquisition system currently under development at KSC consists of the SensorNet(TradeMark) wireless sensors as the remote stations and the central station called the Radio Frequency Health Node (RFHN). The RFF1N is the central station which remotely communicates with the SensorNet(TradeMark) sensors to control them and to receive data. The system's salient feature is the ability to provide deterministic sensor data with accurate time stamps for both time critical and non-time critical applications. Current wireless standards such as Zigbee(TradeMark) and Bluetooth(Registered TradeMark) do not have these capabilities and can not meet the needs that are provided by the SensorNet technology. Additionally, the system has the ability to automatically reconfigure the wireless communication link to a secondary frequency if interference is encountered and can autonomously search for a sensor that was perceived to be lost using the relay capabilities of the sensors and the secondary frequency. The RFHN and the SensorNet designs are based on modular architectures that allow for future increases in capability and the ability to expand or upgrade with relative ease. The RFHN and SensorNet sensors .can also perform data processing which forms a distributed processing architecture allowing the system to pass along information rather than just sending "raw data points" to the next higher level system. With a relatively small size, weight and power consumption, this system has the potential for both spacecraft and aircraft applications as well as ground applications that require time critical data.

Valencia, Emilio J.↗

Auxiliary DCP data acquisition system

An airborne DCP Data Aquisition System has been designed to augment the ERTS satellite data recovery system. The DCP's are data collection platforms located at pertinent sites. With the appropriate sensors they are able to collect, digitally encode and transmit environmental parameters to the ERTS satellite. The satellite in turn relays these transmissions to a ground station for processing. The satellite is available for such relay duty a minimum of two times in a 24-hour period. The equipment is to obtain continuous DCP data during periods of unusual environmental activity--storms, floods, etc. Two circumstances contributed to the decision to design such a system; (1) Wallops Station utilizes surveillance aircraft in support of rocket launches and also in support of earth resources activities; (2) the area in which Wallops is located, the Delaware and Chesapeake Bay areas, are fertile areas for DCP usage. Therefore, by developing an airborne DCP receiving station and installing it on aircraft more continuous DCP data can be provided from sites in the surrounding areas at relatively low cost.

Snyder, R. V.↗

Real-time data acquisition system assists engine test program

The mixed-fuels program examined included two major phases: the development of a reformer that would provide an onboard source of hydrogen, and the testing of induction systems and mixed fuels on a conventional V8 engine to verify the concept and define the system's potential. The discussion is limited to the engine testing phase. The testing program is reviewed and the effectiveness of an IDAC data acquisition system in supporting the engine testing program is demonstrated. The data system's application is illustrated by examples.

Griffin, D. C., Jr.↗