Voyager design study. volume iii- subsystem design, part i
Communications and television subsystems and radar equipment for Mars 1969, 1971, and 1975 and Venus 1970 and 1972 Voyager missions
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Communications and television subsystems and radar equipment for Mars 1969, 1971, and 1975 and Venus 1970 and 1972 Voyager missions
The purpose of this project was research and development of an automobile collision avoidance radar system. The major finding was that the application of radar to the automobile collision avoidance problem deserves continued research even though the specific approach investigated in this effort did not perform adequately in its angle measurement capability. Additional findings were that: (1) preliminary performance requirements of a candidate radar system are not unreasonable; (2) the number and severity of traffic accidents could be reduced by using a collision avoidance radar system which observes a fairly wide (at least + or - 10 deg) field of view ahead of the vehicle; (3) the health radiation hazards of a probable radar design are not significant even when a large number of radar-equipped vehicles are considered; (4) effects of inclement weather on radar operation can be accommodated in most cases; (5) the phase monopulse radar technique as implemented demonstrated inferior angle measurement performance which warrants the recommendation of investigating alternative radar techniques; and (6) extended target and multipath effects, which presumably distort the amplitude and phase distribution across the antenna aperture, are responsible for the observed inadequate phase monopulse radar performance.
The analysis of test films pertaining to the readiness of the Apollo 17 radar equipment is discussed. Emphasis is placed on the evaluation of the lunar sounder equipment. The lunar sounder experiment was to examine the lunar surface at three different radar frequencies of 2 meters, 60 meters, and 20 meters. Test films were made on the lunar sounder system to describe the purpose of the test, to describe the experiments used for analysis, and to provide conclusions reached after analysis.
A tutoral background of radar capabilities and its potential for insect research is provided. The basic principles and concepts of radar were reviewed. Information on current radar equipment was examined. Specific issues related to insect research included; target cross-section, radar frequency, tracking target recognition and false alarms, clutter reduction, radar transmitter power, and ascertained atmospheric processes.
A description of the results of the Venus northern hemisphere radar survey in 1983-1984 from the Venera 15 and 16 spacecrafts is presented. In addition, we discuss some peculiarities in the function of the radar equipment that defined the technology of SAR data processing. Among these peculiarities are insufficient calibration of SAR and radar altimeter and erroneous automatic gain control data transmission from the spacecrafts. As a result, the procedure of image synthesis and mosaicking contained multistage image brightness corrections. This led to the fact that the average image brightness in a spot 100 km in diameter was constant everywhere in the mosaics. Twenty-seven radar mosaics in the Lambert-Hauss conic projection with 1-2 km spatial resolution covering 25 percent of the surface of Venus have been produced. A Venus surface roughness map was constructed by joint processing of SAR and altimeter data. The mutual calibration of the SAR and altimeter was made in the special radar session when the SAR and altimeter were declined from the local vertical at the same angle. The possibility of estimating relative variations in surface reflection properties over a tens-of-kilometers interval from Venera images is still being considered. Joint analysis of the coordinates of small features of the Venera and Magellan images is one more approach being used to refine the period of rotation for Venus.
Improved statistical method of extraction of textural features in synthetic-aperture-radar (SAR) images takes account of effects of scheme used to sample raw SAR data, system noise, resolution of radar equipment, and speckle. Treatment of speckle incorporated into overall statistical treatment of speckle, system noise, and natural variations in texture. One computes speckle auto-correlation function from system transfer function that expresses effect of radar aperature and incorporates range and azimuth resolutions.
Calibration method accounts for characteristics of real radar equipment invalidating standard 2 X 2 complex-amplitude R (receiving) and T (transmitting) matrices. Overall gain in each combination of transmitting and receiving channels assumed different even when only one transmitter and one receiver used. One characterizes departure of polarimetric Synthetic Aperture Radar (SAR) system from simple 2 X 2 model in terms of single parameter used to transform measurements into format compatible with simple 2 X 2 model. Data processed by applicable one of several prior methods based on simple model.
Tracking performance of Apollo land and ship based C band radar equipment
Feasibility study of simulated microwave backscatter from ocean surface as encountered by radar equipment
Telemetry simulations, radar equipment and experiments, and related supporting research for Deep Space Network
Spacecraft radar equipment for remote measurements of ocean characteristics
A coaxial focused CW scanning laser Doppler velocimeter (SLDV) radar equipment applying heterodyne detection at 10.6 microns can measure intensity fluctuations under field conditions. The set includes a 20 W CO2 laser, a coaxial Cassegrainian telescope, standard heterodyne equipment, and a SAW spectrum analyzer with 100 kHz signal resolution. Operation of the equipment and techniques for taking remote measurements are described briefly. Applications to remote measurements of transverse component of wind speed, as a complement to the traditional Doppler method of determining axial velocity, are under study. SLDV equipment has been used in detection, tracking, and measurements of atmospheric turbulence associated with aircraft wing-tip vortices or with dust devils, and in measurement of general atmospheric wind profiles.
A compilation of information regarding systems design of space shuttles used in meteorological radar probes is presented. Necessary radar equipment is delineated, while space system elements, calibration techniques, antenna systems and other subsystems are reviewed.
In 1978 a joint NASA-FAA helicopter flight test was conducted to examine the use of weather-mapping radar for IFR guidance during landing approaches to oil rig helipads. The following navigation errors were measured: total system error, radar-range error, radar-bearing error, and flight technical error. Three problem areas were identified: (1) operational problems leading to pilot blunders, (2) poor navigation to the downwind final approach point, and (3) pure homing on final approach. Analysis of these problem areas suggests improvement in the radar equipment, approach procedure, and pilot training, and gives valuable insight into the development of future navigation aids to serve the off-shore oil industry.
In encounters with microbursts, low altitude aircraft first encounter a strong headwind which increases their wing lift and altitude; this phenomenon is followed in short succession by a decreasing headwind component, a downdraft, and finally a strong tailwind that catastrophically reduces wing lift and precipitates a crash dive. It is noted that the potentially lethal low altitude wind shear of a microburst may lie in apparently harmless, rain-free air beneath a cloud base. Occasionally, such tell-tale signs as localized blowing of ground dust may be sighted in time. Microbursts may, however, occur in the heavy rain of a thunderstorm, where they will be totally obscured from view. Wind shear may be detected by an array of six anemometers and vanes situated in the vicinity of an airport, and by Doppler radar equipment at the airport or aboard aircraft.
Images formed aboard airplane. Data processor for synthetic-aperture radar (SAR) operates aboard airplane with radar equipment to produce images of scanned terrain in real time. Providing images immediately, new processor enables SAR operator to monitor scanning activity. Processed images recorded on tape or transmitted to ground stations.
In the late 1970s and early 1980s, the United States and the Soviet Union sent the Pioneer Venus and Venera spacecraft, respectively, to study Venus more closely and to image its surface with radar. These missions have answered many questions about Venus, but many more questions remain unanswered about the extent to which Venus' surface was shaped by volcanoes, plate tectonics, impact craters, and water and wind erosion. To help answer these remaining questions a new radar imaging spacecraft Magellan will be launched from the Space Shuttle. Magellan will spend eight months mapping most of the planet at a resolution nearly ten times better than any previous views of the surface. The mission of Magellan, the radar equipment, orbiting of Venus, planetary imaging, and surface exploration are discussed.
Improved klystron designed for use as final amplifier in ultrahigh-frequency (UHF) television transmitter. New device incorporates multistage depressed collector (MSDC) of advanced design to increase efficiency by recovering, from spent electron beam, some of residual kinetic energy otherwise dissipated as heat. Concept applied to increase efficiencies of microwave communication, equipment, radar systems, and particle-beam accelerators.