Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Video”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Advanced study of video signal processing in low signal to noise environments

A nonlinear analysis of a multifilter phase-lockloop (MPLL) by using the method of harmonic balance is presented. The particular MPLL considered has a low-pass filter and a band-pass filter in parallel. An analytic expression for the relationship between the input signal phase deviation and the phase error is determined for sinusoidal FM in the absence of noise. The expression is used to determine bounds on the proper operating region for the MPLL and to investigate the jump phenomenon previously observed. From these results the proper modulation index, modulating frequency, etc. used for the design of a MPLL are determined. Data for the loop unlock boundary obtained from the theoretical expression are compared to data obtained from analog computer simulations of the MPLL.

Carden, F.↗
NASA NTRS1973

A zero-error operational video data compression system

A data compression system has been operating since February 1972, using ATS spin-scan cloud cover data. With the launch of ITOS 3 in October 1972, this data compression system has become the only source of near-realtime very high resolution radiometer image data at the data processing facility. The VHRR image data are compressed and transmitted over a 50 kilobit per second wideband ground link. The goal of the data compression experiment was to send data quantized to six bits at twice the rate possible when no compression is used, while maintaining zero error between the transmitted and reconstructed data. All objectives of the data compression experiment were met, and thus a capability of doubling the data throughput of the system has been achieved.

Kutz, R. L.↗
NASA NTRS1973

Video-signal improvement using comb filtering techniques.

Significant improvement in the signal-to-noise performance of television signals has been obtained through the application of comb filtering techniques. This improvement is achieved by removing the inherent redundancy in the television signal through linear prediction and by utilizing the unique noise-rejection characteristics of the receiver comb filter. Theoretical and experimental results describe the signal-to-noise ratio and picture-quality improvement obtained through the use of baseband comb filters and the implementation of a comb network as the loop filter in a phase-lock-loop demodulator. Attention is given to the fact that noise becomes correlated when processed by the receiver comb filter.

Arndt, G. D.↗
NASA NTRS1973

Video instrumentation for radionuclide angiocardiography.

Two types of videoscintiscopes for performing radioisotopic angiocardiography with a scintillation camera are described, and use of these instruments in performing clinical studies is illustrated. Radionuclide angiocardiography is a simple, quick and accurate procedure recommended as a screening test for patients with a variety of congenital and acquired cardiovascular lesions. When performed in conjunction with coronary arterial catheterization, dynamic radionuclide angiography may provide useful information about regional myocardial perfusion. Quantitative capabilities greatly enhance the potential of this diagnostic tool.

Kriss, J. P.↗
NASA NTRS1973

Advanced study of video signal processing in low signal to noise environments

Conventional analytical techniques used to determine and optimize phase-lock loop (PLL) characteristics are most often based on a model which is valid only if the intermediate frequency (IF) filter bandwidth is large compared to the PLL bandwidth and the phase error is small. An improved model (called the quasi-linear model) is developed which takes into account small IF filter bandwidths and nonlinear effects associated with large phase errors. By comparison of theoretical and experimental results it is demonstrated that the quasi-linear model accurately predicts PLL characteristics. This is true even for small IF filter bandwidths and large phase errors where the conventional model is invalid. The theoretical and experimental results are used to draw conclusions concerning threshold, multiplier output variance, phase error variance, output signal-to-noise ratio, and signal distortion. The relationship between these characteristics and IF filter bandwidth, modulating signal spectrum, and rms deviation is also determined.

Carden, F.↗
NASA NTRS1973

Overshoot suppression in Adaptive Delta Modulator links for video transmission

An overshoot suppression scheme to improve the performance of the Digital Song Adaptive Delta Modulator for picture transmission is described. The overshoot suppression algorithm has been verified using computer simulation on a PDP-8. It is also shown that the additional hardware required for the actual implementation of the algorithm is simpler than those encountered in the literature, and gives better signal tracking accuracy.

Weiss, L.↗
NASA NTRS1973

Video systems for real-time oil-spill detection

Three airborne television systems are being developed to evaluate techniques for oil-spill surveillance. These include a conventional TV camera, two cameras operating in a subtractive mode, and a field-sequential camera. False-color enhancement and wavelength and polarization filtering are also employed. The first of a series of flight tests indicates that an appropriately filtered conventional TV camera is a relatively inexpensive method of improving contrast between oil and water. False-color enhancement improves the contrast, but the problem caused by sun glint now limits the application to overcast days. Future effort will be aimed toward a one-camera system. Solving the sun-glint problem and developing the field-sequential camera into an operable system offers potential for color 'flagging' oil on water.

Millard, J. P.↗
NASA NTRS1976

Video display synthesizer

Dc command voltages from analog computer can be displayed as four dots and two crosshairs configured to provide illusion of depth via planar or stereo presentations in monochrome or color and if stereo, using dual monitors, single monitor with split screen, or single monitor with color separation.

Grant, C.↗
NASA NTRS1975

Design of a video system providing optimal visual information for controlling payload and experiment operations with television

A program was conducted which included the design of a set of simplified simulation tasks, design of apparatus and breadboard TV equipment for task performance, and the implementation of a number of simulation tests. Performance measurements were made under controlled conditions and the results analyzed to permit evaluation of the relative merits (effectivity) of various TV systems. Burden factors were subsequently generated for each TV system to permit tradeoff evaluation of system characteristics against performance. For the general remote operation mission, the 2-view system is recommended. This system is characterized and the corresponding equipment specifications were generated.

Source record↗
NASA NTRS1974

ASTP video tape recorder ground support equipment (audio/CTE splitter/interleaver). Operations manual

A descriptive handbook for the audio/CTE splitter/interleaver (RCA part No. 8673734-502) was presented. This unit is designed to perform two major functions: extract audio and time data from an interleaved video/audio signal (splitter section), and provide a test interleaved video/audio/CTE signal for the system (interleaver section). It is a rack mounting unit 7 inches high, 19 inches wide, 20 inches deep, mounted on slides for retracting from the rack, and weighs approximately 40 pounds. The following information is provided: installation, operation, principles of operation, maintenance, schematics and parts lists.

Source record↗
NASA NTRS1975

ASTP video tape recorder ground support equipment, addendum 2 (CTE splitter/buffer). Operations manual

A descriptive handbook for the CTE splitter (RCA part No. 8673734-50A) was presented. This unit is designed to extract time data from an interleaved video/audio signal. It is a rack mounting unit 7 inches high, 19 inches wide, 20 inches deep, mounted on slides for retracting from the rack, and weighs approximately 40 pounds. The following information is provided: installation, operation, principles of operation, maintenance, schematics and parts lists.

Source record↗
NASA NTRS1978

Video method for studying optical fields

Approach for measuring intensity distribution in optical field records pattern with vidicon and then displays it on oscilloscope, using vertical sweep as trigger. Single horizontal lines in field can be isolated by using sweep delay feature of oscilloscope.

Mezrich, R. S.↗
NASA NTRS1979

Improving low-illumination video

Nonmoving TV pictures are improved by electronic system that removes much of the "snow" or random noise in image. System integrates and averages picture elements in real time and thereby allows easier and more accurate evaluation of image, visually and by computer.

Sapirstein, R. L.↗
NASA NTRS1980

Video distribution system cost model

A cost model that can be used to systematically identify the costs of procuring and operating satellite linked communications systems is described. The user defines a network configuration by specifying the location of each participating site, the interconnection requirements, and the transmission paths available for the uplink (studio to satellite), downlink (satellite to audience), and voice talkback (between audience and studio) segments of the network. The model uses this information to calculate the least expensive signal distribution path for each participating site. Cost estimates are broken downy by capital, installation, lease, operations and maintenance. The design of the model permits flexibility in specifying network and cost structure.

Gershkoff, I.↗
NASA NTRS1979

Video techniques in comet-debris studies

The paper describes techniques for examining comets and meteors. Data was obtained on four nights around the peak of the Geminid shower, using SEC Vidicon equipment at Mount Hopkins Observatory in Arizona at a latitude of 31 deg 41.9 north, longitude 110 deg 52.7 west, and 2320 meters above sea level. The TV employed, was mated to an f/0.75 lens of 105 mm focal length, and agove the lens a transmission diffraction grating was fixed with 300 lines/mm. Attention is given to the calibration curve of the seven-pixer means and to the contour lines drawn by the Image Data Processing System (IDAPS).

Millman, P. M.↗