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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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System with single, standard, wideband line transmits ten or more real time TV video data displays over hard wire to recorders more than 22.5 km from source. Digital logic and integrated circuits ensure high reliability and low maintenance. System is adaptable for video sampling applications.
Computer refreshed display for processing video information with digital computer to enhance video data
Video signal processing system for sampling video brightness levels
Mathematical expressions describe an FM signal modulated by a composite video wave. Three general spectrum equations for FM signals are obtained by using three types of video information.
The feasibility of automatically reducing a form of pictorial aerodynamic heating data is discussed. The imagery, depicting the melting history of a thin coat of fusible temperature indicator painted on an aerodynamically heated model, was previously reduced by manual methods. Careful examination of various lighting theories and approaches led to an experimentally verified illumination concept capable of yielding high-quality imagery. Both digital and video image processing techniques were applied to reduction of the data, and it was demonstrated that either method can be used to develop superimposed contours. Mathematical techniques were developed to find the model-to-image and the inverse image-to-model transformation using six conjugate points, and methods were developed using these transformations to determine heating rates on the model surface. A video system was designed which is able to reduce the imagery rapidly, economically and accurately. Costs for this system were estimated. A study plan was outlined whereby the mathematical transformation techniques developed to produce model coordinate heating data could be applied to operational software, and methods were discussed and costs estimated for obtaining the digital information necessary for this software.
An investigation of threshold effects in FM TV was initiated to determine if any simple, low cost techniques were available which can reduce the subjective video threshold, applicable to low cost community TV reception via satellite. Two methods of eliminating these effects were examined: the use of standard video pre-emphasis, and the use of an additional circuit to blank the picture tube during the retrace period.
A paper describing the basic delta modulation systems studied was published. A second paper, describing the systems response to voice and video was presented at the International Communications Conference in June 1972, and a third paper describing several delta modulation systems used for voice and video is scheduled for presentation at the National Telecommunications Conference in December 1972.
Run-length encoding is a scheme which has been used to remove redundancy from video signals. Based upon a first-order Markov model of video data, an upper bound on compression ratio is found for run-length encoding. It is shown that at best run-length encoding will give a compression ratio which is approximately 60% of the maximum attainable value. This percentage is fairly independent of the particular picture involved.
Description of the image-processing system for the Earth Resources Technology Satellite (ERTS), which will process video-tape recordings received from the satellite into imagery and digitized video data suitable for earth-resource study and analysis. The system is made up of three subsystems. The bulk processor produces 70-mm images and digitized records, corrected for systematic geometric and radiometric errors as well as for sensor-calibration and other errors. The precision processor modifies the bulk images to significantly increase geometric precision. The special processor transfers either bulk or precision data to computer-compatible tape.
The overall data link commences with the lens of the spacecraft camera, followed by the telemetry format, and then the passing of the data onto a spacecraft tape recorder for later transmission at a slower rate. The properties of the individual pieces of information are described, and rate distortion theory is discussed. The video channel from the standpoint of information theory, and fidelity criteria for planetary video are considered. Areas for further research are indicated.
Means of obtaining improved dimensional measurements from neutron radiographs of nuclear fuel elements are discussed. The use of video-electronic image analysis relative to edge definition in radiographic images is described. Based on this study, an edge definition criterion is proposed for overcoming image unsharpness effects in taking accurate diametral measurements from radiographs. An electronic density slicing method for automatic edge definition is described. Results of measurements made with video micrometry are compared with scanning microdensitometer and micrometric physical measurements. An image quality indicator for estimating photographic and geometric unsharpness is described.
The results are presented of a study of source coding, modulation/channel coding, and systems techniques for application to teleconferencing over high data rate digital communication satellite links. Simultaneous transmission of video, voice, data, and/or graphics is possible in various teleconferencing modes and one-way, two-way, and broadcast modes are considered. A satellite channel model including filters, limiter, a TWT, detectors, and an optimized equalizer is treated in detail. A complete analysis is presented for one set of system assumptions which exclude nonlinear gain and phase distortion in the TWT. Modulation, demodulation, and channel coding are considered, based on an additive white Gaussian noise channel model which is an idealization of an equalized channel. Source coding with emphasis on video data compression is reviewed, and the experimental facility utilized to test promising techniques is fully described.
Video data from the Earth Resources Technology Satellite (ERTS) are entered into the initial image generation system and placed on film using an electron beam to correct for both radiometric and geometric errors, a hardware unit called EBRIC was designed, fabricated, and incorporated in the image processing system. It operates under the control of a process control computer, as it varies video signal and the x and y deflection signals of the EBR.
A television multiplexing system which includes a circuit that inserts a digital codes sync signal and a digital code into a video signal for identifying the channel is described. The digital sync signal and the digital coded signals are generated by a single crystal controlled clock so that they are always in synchronism with each other. In demultiplexing the signals are utilized for shifting the digital coded signals into a shift register. The shift register, in turn, activates a decoder according to the code stored in the shift register for selecting the proper recording disk or receiver for storing the video signal.
This paper concerns satellite repeater tradeoffs for a multiple-beam, multiple-channel, multiple-connectivity satellite postulated to serve a diversity of domestic U.S. noncommercial requirements, with a substantial portion of the satellite power, weight, and bandwidth dedicated to video distribution and bradcast. The orders-of-magnitude of the requirements are given for the video plus high-rate data traffic category. The designs of two alternative baseline repeater configurations are presented, and estimates of their weight and their prime power consumption are given. These data are the basis for estimating the weight and power consumption of a range of alternative beam coverage, modulation, and channel capacity systems. These estimates are used to illustrate tradeoffs with different performance criteria as the independent variable: number of channels per beam and total number of beam-channels.
The acquisition system which operates in conjunction with a balloon-borne TV system, boresighted to a telescope is described. It has two main functions, a star field monitor and an offset star tracker. The design of the system was strongly influenced by the TV camera, which uses the same interlaced scanning system as is employed in commercial television broadcasting. To reduce power and bandwidth requirements, the star field information transmitted in our system consists only of the horizontal and vertical coordinates of each star and its brightness. As a star field monitor the system provides video thresholding, camera blemish suppression, coordinate digitization in 3 axes, circuity to recognize as single star the dispersed video signals resulting from one star overlapping adjacent scanning lines and storage of all signals for readout by the telemetry at appropriate times.
The encoding of video signals using the Song Adaptive Delta Modulator (Song ADM) is discussed. The video signals are characterized as a sequence of pulses having arbitrary height and width. Although the ADM is suited to tracking signals having fast rise times, it was found that the DM algorithm (which permits an exponential rise for estimating an input step) results in a large overshoot and an underdamped response to the step. An overshoot suppression algorithm which significantly reduces the ringing while not affecting the rise time is presented along with formuli for the rise time and the settling time. Channel errors and their effect on the DM encoded bit stream were investigated.
A remote sensing oculometer has been successfully operated during flight tests. This device was able to track the pilot's eye-point-of-regard (lookpoint) consistently and unobtrusively in the flight environment. The instantaneous position of the lookpoint was determined to within approximately 1 degree. Data were recorded on both analog and video tape. The video data consisted of continuous scenes of the aircraft's instrument display and a superimposed white dot (simulating the lookpoint) dwelling or moving from instrument to instrument as the pilot monitored the display information during landing approaches.