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An adaptive video compressor was designed as part of the CTS Digital Video Curriculum Sharing Experiment. The compressor was constructed using field-to-field differencing on fields processed using a Hadamard transform method. The spatial resolution was improved using a fixed-rate, three-mode adaptive system to compress each field.
Video scrambler that operates on baseband signals uses relatively simple delay and inversion circuitry to alter television signal so that is is unrecognizable when picked up on TV monitor. Descrambler that uses essentially same circuit restores signal and allows original video information to be retrieved. Circuits allow only authorized parties to have access to transmitted information.
A microprocessor-based development system was designed and fabricated for prototype test of navigation receiver designs. During use of this system in the development of low-cost LORAN-C receiver/processor concepts, the limitations of the integral KIM-1 display were severely felt. It was to augment this numerical display that the video character display was produced. The circuit design presented meets the need for a flexible-format display capable of driving a small standard video monitor with only minimal demands upon microprocessor memory and MPU cycles.
The Space Shuttle initially will be using a field-sequential color television system but it is possible that an NTSC color TV system may be used for future missions. In addition to downlink color TV transmission via analog FM links, the Shuttle will use a high resolution slow-scan monochrome system for uplink transmission of text and graphics information. This paper discusses the characteristics of the Shuttle video systems, and evaluates digitization and/or bandwidth compression techniques for the various links. The more attractive techniques for the downlink video are based on a two-dimensional DPCM encoder that utilizes temporal and spectral as well as the spatial correlation of the color TV imagery. An appropriate technique for distortion-free coding of the uplink system utilizes two-dimensional HCK codes.
Research work is described that was carried out to develop adaptive delta modulators (ADM) capable of encoding black-and-white and color video signals in the presence of high bit error rates. These were a one-dimensional ADM capable of encoding black-and-white pictures and transmitting digitally encoded voice without increase in bandwidth; an ADM capable of encoding color video signals; and an ADM capable of encoding field-sequential color. For each of these three units, the bit rate could be adjusted within the range from 6 to 24 Mbits/sec. The effects of the bit rate and channel errors on the response of the picture are examined.
This paper compares theoretical and experimental picture compression designs, for images processed in 8 x 8 blocks using the Walsh-Hadamard transform (WHT). The optimum picture compression design is well known, if the mean-square error (mse) is used as the measure of distortion, and if it is assumed that the video process is a stationary first-order Markov process with a Gaussian distribution. This theoretical design gives useful results when the transform processing is done on full pictures, but gives inferior results (relative to empirical design) when transform processing is done on small 8 x 8 blocks. The use of non-Gaussian distributions for the transform components fails to improve this poor performance, which is due to the nonstationary nature of the video process. An experimentally based design procedure, which considers nonstationarity, yields significantly improved mse and subjective performance.
Architectural requirements of a minicomputer-based specialized complex for automated digital analysis of multizonal video data are examined. The logic structure of multizonal video data and the complex mathematical provision required for the analysis of such data are described. The composition of the specialized complex, its operating system, and the required set of peripheral devices are discussed. It is noted that although much of the analysis can be automated, the operator-computer dialog mode is essential for certain stages of the analysis.
The functions were discribed and the operating instructions, the block diagram and the proposed versions are given for modifying the program in order to obtain the statistical characteristics of multi-channel video information. The program implements certain man-machine methods for investigating video information. It permits representation of the material and its statistical characteristics in a form which is convenient for the user.
This paper presents the initial results of our study of the use of adaptive delta modulation to encode color signals. The techniques considered include direct encoding of the color video signal, encoding of each of the three color components, i.e., R, G and B, and encoding of the chrominance and luminance signals I, Y and Q. It is shown that at any transmitted bit rate between 8 Mb/s and 24 Mb/s the best quality picture reproduction occurs when the I, Y and Q signals are encoded and the poorest quality picture reproduction occurs when the composite video signal is encoded. Furthermore, the differences in quality are significant.
Color video display techniques for flow field surveys are presented. The following techniques were examined: traverse device, used for flow field surveys above and behind finite wing models; flow chart of data reduction for color video display technique; location of spanwise survey stations above and behind wing; hot wire data at first three survey stations on fully stalled wing; hot wire data at last three stations behind fully stalled wing; hot wire and pitch probe data; magnitude of velocity, yaw angle, pitch angle, and cross flow direction from 5 tube survey at X/C = 2.70 behind fully stalled wing.
As a part of NASA's Rotorcraft All-Weather Operations Research Program, advanced airborne radar approach (ARA) concepts are being investigated. Since data from previous NASA/FAA flight tests showed significant ARA limitations, a research program was initiated at NASA Ames Research Center to determine the benefit that could be derived by automating certain radar functions and superimposing course display data on the radar display. To evaluate these concepts, a newly developed video tracking system which interfaces with weather radar was acquired. After the pilot designates a destination target, the system tracks the target video as it moves on the radar indicator. Using a small, efficient microprocessor, the autotracker presents valuable approach data on the radar screen and automatically adjusts the radar gain and tilt. Results of a limited flight test evaluation of the autotracker show that the course display concept, combined with automated gain and tilt functions, is effective for improving ARA's and reducing radar operator workload.
A video recording system with a visible light blocking filter to give sensitivity in the 0.78 m to 1.1 m waveband detected freeze-damaged citrus leaves rapidly. With this technique, the time to analyze images can be decreased from about one day for conventional photography to less than one hour for video recording.
The critical elements of an autonomous video rendezvous and docking system were built and used successfully in a physical laboratory simulation. The laboratory system demonstrated that a small, inexpensive electronic package and a flight computer of modest size can analyze television images to derive guidance information for spacecraft. In the ultimate application, the system would use a docking aid consisting of three flashing lights mounted on a passive target spacecraft. Television imagery of the docking aid would be processed aboard an active chase vehicle to derive relative positions and attitudes of the two spacecraft. The demonstration system used scale models of the target spacecraft with working docking aids. A television camera mounted on a 6 degree of freedom (DOF) simulator provided imagery of the target to simulate observations from the chase vehicle. A hardware video processor extracted statistics from the imagery, from which a computer quickly computed position and attitude. Computer software known as a Kalman filter derived velocity information from position measurements.
A photogrammetric closed circuit television system to measure model deformation at the National Transonic Facility is described. The photogrammetric approach was chosen because of its inherent rapid data recording of the entire object field. Video cameras are used to acquire data instead of film cameras due to the inaccessibility of cameras which must be housed within the cryogenic, high pressure plenum of this facility. A rudimentary theory section is followed by a description of the video-based system and control measures required to protect cameras from the hostile environment. Preliminary results obtained with the same camera placement as planned for NTF are presented and plans for facility testing with a specially designed test wing are discussed.
Two noncontacting and nondestructive, remotely controlled methods of measuring the progress of oxidation/corrosion/erosion of metal alloys, exposed to flame test conditions, are described. The external diameter of a sample under test in a flame was measured by a video camera width measurement system. An eddy current proximity probe system, for measurements outside of the flame, was also developed and tested. The two techniques were applied to the measurement of the oxidation of 304 stainless steel at 910 C using a Mach 0.3 flame. The eddy current probe system yielded a recession rate of 0.41 mils diameter loss per hour and the video system gave 0.27.
A study of a low-rate monochrome video compression system is presentd in this paper. This system is a conditional-replenishment coder that uses two-dimensional Walsh-transform coding within each video frame. The conditional-replenishment algorithm works by transmitting only the portions of an image that are changing in time. This system is augmented with a motn-prediction algorithm that measures spatial dispalcement parameters from frame to frame, and codes the data using these parameters. A comparison is made between the conditional-replenishment system with, and without, the motion-predictinalgorthm. Subsampling in time is ued to maintain the data rate rate at a fixed value. Average bit rates of 1 bit/picture element (pel) to 1/16 bit/pel are considered. The resultant performance of the compression simulations is presented in terms of the average frame rates produced.
Microprocessor-based system originally developed for anthropometric research merges digital data with video images for storage on video cassette recorder. Combined signals later retrieved and displayed simultaneously on television monitor. System also extracts digital portion of stored information and transfers it to solid-state memory.
Data compression allows video signals to be transmitted economically on telephone circuits. Telephone lines transmit television signals to remote traffic-control center. Lines also carry command signals from center to TV camera and compressor at highway site. Video system with television cameras positioned at critical points on highways allows traffic controllers to determine visually, almost immediately, exact cause of traffic-flow disruption; e.g., accidents, breakdowns, or spills, almost immediately. Controllers can then dispatch appropriate emergency services and alert motorists to minimize traffic backups.