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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

A system for the real-time display of radar and video images of targets

Described here is a software and hardware system for the real-time display of radar and video images for use in a measurement range. The main purpose is to give the reader a clear idea of the software and hardware design and its functions. This system is designed around a Tektronix XD88-30 graphics workstation, used to display radar images superimposed on video images of the actual target. The system's purpose is to provide a platform for tha analysis and documentation of radar images and their associated targets in a menu-driven, user oriented environment.

Allen, W. W.↗
NASA NTRS1991

Digital CODEC for real-time processing of broadcast quality video signals at 1.8 bits/pixel

Advances in very large scale integration and recent work in the field of bandwidth efficient digital modulation techniques have combined to make digital video processing technically feasible an potentially cost competitive for broadcast quality television transmission. A hardware implementation was developed for DPCM (differential pulse code midulation)-based digital television bandwidth compression algorithm which processes standard NTSC composite color television signals and produces broadcast quality video in real time at an average of 1.8 bits/pixel. The data compression algorithm and the hardware implementation of the codec are described, and performance results are provided.

Shalkhauser, Mary JO↗
NASA NTRS1992

Video System Highlights Hydrogen Fires

Video system combines images from visible spectrum and from three bands in infrared spectrum to produce color-coded display in which hydrogen fires distinguished from other sources of heat. Includes linear array of 64 discrete lead selenide mid-infrared detectors operating at room temperature. Images overlaid on black and white image of same scene from standard commercial video camera. In final image, hydrogen fires appear red; carbon-based fires, blue; and other hot objects, mainly green and combinations of green and red. Where no thermal source present, image remains in black and white. System enables high degree of discrimination between hydrogen flames and other thermal emitters.

Youngquist, Robert C.↗
NASA NTRS1992

The Center/TRACON Automation System (CTAS): A video presentation

NASA Ames, working with the FAA, has developed a highly effective set of automation tools for aiding the air traffic controller in traffic management within the terminal area. To effectively demonstrate these tools, the video AAV-1372, entitled 'Center/TRACON Automation System,' was produced. The script to the video is provided along with instructions for its acquisition.

Green, Steven M.↗
NASA NTRS1992

Technical and economic feasibility of integrated video service by satellite

The trends and roles of satellite based video services in the year 2010 time frame are examined based on an overall network and service model for that period. Emphasis is placed on point to point and multipoint service, but broadcast could also be accommodated. An estimate of the video traffic is made and the service and general network requirements are identified. User charges are then estimated based on several usage scenarios. In order to accommodate these traffic needs, a 28 spot beam satellite architecture with on-board processing and signal mixing is suggested.

Price, Kent M.↗
NASA NTRS1992

Video Guidance Sensor for automated capture

The paper describes a video-based sensor, the Video Guidance Sensor, which has been developed for use in automated docking systems or for automated capture with robotic systems. The sensor itself consists of several basic components: IR diode illuminators, a solid-state camera, a frame grabber, and a microprocessor. The target consists of three circular retroreflectors evenly spaced in a line with the middle reflector mounted on a short pole. Each retroreflector has a narrow bandpass optical filter in front of it. From this sensor and target configuration, the positions and attitudes of the target relative to the sensor can be determined. The position information can be differenced to with respect to time in order to obtain the relative positional and angular velocities. That information is sufficient to perform automated docking, berthing, or capture. The paper gives details of the sensor's make-up, including accuracies, noise characteristics, and operating ranges.

Howard, R. T.↗
NASA NTRS1992

Observation of alloy solidification using high-speed video

A high-speed video instrumentation system was used to observe solidification of undercooled Ti-51 at. pct Al. The camera system developed by Battelle is capable of operation at rates up to 12,000 frames per second. The system digitizes and stores video images acquired by a 64 x 64 pixel silicon photodiode array. In a joint effort with Vanderbilt University the camera was used to observe three transformations of the undercooled alloys, using containerless processing by electromagnetic levitation. The first was solidification where nucleation was induced at an undercooling of 9 percent Tl, where Tl is the liquidus temperature of the alloy, and the second was solidification where nucleation was spontaneous at an undercooling of 15 percent Tl. The third event was a solid-state nucleation and growth transformation following the solidification at an undercooling of 15 percent Tl.

Bassler, B. T.↗
NASA NTRS1990

Laboratory calibration and characterization of video cameras

Some techniques for laboratory calibration and characterization of video cameras used with frame grabber boards are presented. A laser-illuminated displaced reticle technique (with camera lens removed) is used to determine the camera/grabber effective horizontal and vertical pixel spacing as well as the angle of nonperpendicularity of the axes. The principal point of autocollimation and point of symmetry are found by illuminating the camera with an unexpanded laser beam, either aligned with the sensor or lens. Lens distortion and the principal distance are determined from images of a calibration plate suitably aligned with the camera. Calibration and characterization results for several video cameras are presented. Differences between these laboratory techniques and test range and plumb line calibration are noted.

Burner, A. W.↗
NASA NTRS1991

An all digital implementation of a modified Hamming net for video compression with prediction and quantization circuits

The hardware and algorithms used to vector quantize (VQ) predicted pixel intensity differences for real-time video compression are described. The hardware is designed for rapid vector quantization performance, which entails the development of application-specific associative memory circuits. A modified DPCM algorithm is originally examined to determine how neural circuitry could enhance its operation. It was determined that quantization and encoding could be improved by consolidating these two functions into one, and by increasing the amount of information (i.e. number of pixels) quantized at a time. The result is a predictive scheme that vector quantizes differential values. Some of the disadvantages of VQ algorithms are solved using associative memories. The video compression algorithm and the associative memory design are described.

Kaul, Richard↗
NASA NTRS1993

Recent experiences with implementing a video based six degree of freedom measurement system for airplane models in a 20 foot diameter vertical spin tunnel

A model space positioning system (MSPS), a state-of-the-art, real-time tracking system to provide the test engineer with on line model pitch and spin rate information, is described. It is noted that the six-degree-of-freedom post processor program will require additional programming effort both in the automated tracking mode for high spin rates and in accuracy to meet the measurement objectives. An independent multicamera system intended to augment the MSPS is studied using laboratory calibration methods based on photogrammetry to characterize the losses in various recording options. Data acquired to Super VHS tape encoded with Vertical Interval Time Code and transcribed to video disk are considered to be a reasonable priced choice for post editing and processing video data.

Snow, Walter L.↗
NASA NTRS1993

Digital data over video channels - Techniques for Spacelab

A study was made of various techniques for transmitting digital data over a composite video channel. Transmitting data from experiments on the Space Shuttle Orbiter over a video channel is attractive since extra channel capacity is needed. Broadcast television telecommunications schemes and other techniques described in the literature were reviewed and compared. PSK (Phase Shift Keying), MPSK (m-ary PSK), or PAM (Pulse Amplitude Modulation) can be transmitted on visible lines of a frame, unassigned lines of the VBI (Vertical Blanking Interval), or during the HBI (Horizontal Blanking Interval). All three modulation techniques can be attractive under the proper conditions. However, PAM on visible lines or during the VBI should be relatively easy to implement, provide adequate average data rates, and give acceptable BERs (Bit Error Rates).

Smith, Dean L.↗
NASA NTRS1993

Techniques for transmitting digital data on the Spacelab's analog video channel

A study was made of various techniques for transmitting digital data over a composite video channel. Transmitting data from experiments on the Space Shuttle Orbiter over a video channel is attractive since extra channel capacity is needed. Broadcast television telecommunications schemes and other techniques described in the literature were reviewed and compared. PSK (Phase Shift Keying), MPSK (m-ary PSK), or PAM (Pulse Amplitude Modulation) can be transmitted on visible lines of a frame, unassigned lines of the VBI (Vertical Blanking Interval), or during the HBI (Horizontal Blanking Interval). All three modulation techniques can be attractive under the proper conditions. However, PAM on visible lines or during the VBI should be relatively easy to implement, provide adequate average data rates, and give acceptable BERs (Bit Error Rates).

Smith, Dean L.↗
NASA NTRS1993

The calibration of video cameras for quantitative measurements

Several different recent applications of velocimetry at Langley Research Center are described in order to show the need for video camera calibration for quantitative measurements. Problems peculiar to video sensing are discussed, including synchronization and timing, targeting, and lighting. The extension of the measurements to include radiometric estimates is addressed.

Snow, Walter L.↗
NASA NTRS1994

Use Of Video In Microscopic And Ultrasonic Inspection

Two combinations of video and image-data-processing techniques, tone-pulse encoding and precision acoustic imaging, yield grain- and pore-size distributions. Knowledge of such and of fiber orientation important because these characteristics directly related to tensile strength, hardness, fracture toughness, fracture stress, and resistance to impact. One of these combinations of techniques used in nondestructive evaluation of composite parts; both play important roles in development of lightweight composites for use at high temperatures in advanced engines and aircraft. Video system provides easy access to information on diffraction and refraction like that described in article, "Ultrasonic Inspection With Angular-Power-Spectrum Scanning" (LEW-15386).

Generazio, Edward R.↗
NASA NTRS1993

Adaptive analog video signal conditioner

This paper presents an adaptive analog video signal conditioner. This system supplements conventional irises and automatic gain controls to condition video signals for digitizing with a uniform analog-to-digital converter. Employing two degree of freedom, this circuit adjusts an analog gain and analog offset to increase the average information content of digitized images as defined by an entropy measure. The globally near-optimized implementation tracks smoothly to adapt to changing scene conditions.

Jeong, Cheol-Ho↗
NASA NTRS1993

Reducing video frame rate increases remote optimal focus time

Twelve observers made best optical focus adjustments to a microscope whose high-resolution pattern was video monitored and displayed first on a National Television System Committee (NTSC) analog color monitor and second on a digitally compressed computer monitor screen at frame rates ranging (in six steps) from 1.5 to 30 frames per second (fps). This was done to determine whether reducing the frame rate affects the image focus. Reducing frame rate has been shown to be an effective and acceptable means of reducing transmission bandwidth of dynamic video imagery sent from Space Station Freedom (SSF) to ground scientists. Three responses were recorded per trial: time to complete the focus adjustment, number of changes of focus direction, and subjective rating of final image quality. It was found that: the average time to complete the focus setting increases from 4.5 sec at 30 fps to 7.9 sec at 1.5 fps (statistical probability = 1.2 x 10(exp -7)); there is no significant difference in the number of changes in the direction of focus adjustment across these frame rates; and there is no significant change in subjectively determined final image quality across these frame rates. These data can be used to help pre-plan future remote optical-focus operations on SSF.

Haines, Richard F.↗
NASA NTRS1994

Voice and video transmission using XTP and FDDI

The use of Xpress Transfer Protocol (XTP) and Fiber Distributed Data Interface (FDDI) provides a high speed and high performance network solution to multimedia transmission that requires high bandwidth. FDDI is an ANSI and ISO standard for a MAC and physical layer protocol that provides a signaling rate of 100 Mbits/sec and fault tolerance. XTP is a transport and network layer protocol designed for high performance and efficiency and is the heart of the SAFENET Lightweight Suite for systems that require performance or realtime communications. The testbed consists of several commercially available Intel based i486 PC's containing off-the-shelf FDDI cards, audio analog-digital converter cards, video interface cards, and XTP software. Unicast, multicast, and duplex audio transmission experiments have been performed using XTP software. Unicast and multicast video transmission is in progress. Several potential commercial applications are described.

Drummond, John↗