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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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Ultraminiature television camera with a total volume of 20.25 cubic inches, requires 28 vdc power, operates on UHF and accommodates standard 8-mm optics. It uses microelectronic assembly packaging techniques and contains a magnetically deflected and electrostatically focused vidicon, automatic gain control circuit, power supply, and transmitter.
Gemini IX experiments - zodiacal light and airglow horizon photography, micrometeorite collection, body fluid bioassay, astronaut maneuvering unit, and UHF-VHF polarization
Optical and UHF Doppler /UDOP/ tracking for lift-off phase of Saturn SA-5 launch vehicle
Input admittances of imperfectly conducting dipole antennas in UHF range for various antenna lengths
VHF and UHF electromagnetic noise levels survey in urban and rural areas to establish satellite- to-ground TV and voice-radio reception system requirements
Survey, consisting of limited noise measurements, was made to augment and verify existing data at HF and VHF and to obtain basic data at UHF. Exact frequencies were determined by the absence of intentionally generated signals around three selected frequencies.
Laboratory and flight tests of airborne solid state UHF telemetry transmitter, discussing miniaturized coaxial hardware from RF power conservation viewpoint
UHF satellite receiver for binary FSK data collection system using matched integrate and dump filter detectors
Satellite microwave receiver systems which convert carrier frequencies and modulation formats to produce signals compatible with VHF-UHF television receivers for low-cost service
Spiral and helical UHF antennas for home TV reception via satellite broadcast relay system
Breadboard model of high power UHF transmitter for space communication satellite
RF noise surveys in urban areas for effective space to earth communication link design at UHF
Negative-resistance circuits with possible space flight applications are discussed. The basic design approach is to use impedance rotation, i.e., the conversion from capacitance to negative resistance, and from resistance to inductance by the phase shift of the transistor current gain at high frequencies. The subjects discussed in detail are the following: hybrid fabrication of VHF and UHF negative-resistance stages with lumped passive elements; formulation of measurement techniques to characterize transistors and to extend the frequency of negative-resistance transistor amplifiers to higher microwave frequencies; and derivation of transistor characteristics required to increase the frequency range of negative-resistance transistor stages.
On the basis of earth observations of the HF and UHF radio emission generated near Jupiter, the presence of energetic charged particles trapped in the planet's dipole magnetic field has been inferred. For electrons, energies of the order of 10 MeV and peak fluxes of the order of 10 to the 7th power per square centimeter per second can be derived from the data for equatorial regions about two planetary radii from the dipole. Energetic protons and lower-energy electrons and protons are also expected, but the limited data require that their fluxes be based on theory or earth analogy. Because descriptions available in the literature suggest large associated uncertainties, both nominal and limiting models for the charged-particle populations of Jupiter's belts are derived. These new engineering models describe electron and proton fluxes and their distributions in energy and position in forms suitable as space vehicle design criteria.
An empirical approach to modeling the electron-density irregularities in the F layer of the earth's ionosphere that are primarily responsible for scintillation of transatmospheric VHF-UHF signals has been devised and tested. The work was directed toward two major goals: first, development of a worldwide model for describing the rms fluctuation in signal strength to be expected on an arbitrary satellite-to-earth communication link under average ionospheric conditions; and, second, investigation of the feasibility of similar modeling for description of the complete first-order distribution of signal strength.
Details of magnetic field conclusions, UHF radio data sets, and the theoretical synchrotron radiation descriptions are summarized for several published and unpublished analyses. The relatively compact set of electron models inspires some confidence in their validity, particularly as they have been derived from numerous data and analysis techniques. Although the models have serious consequences for spacecraft design, the problems they imply are probably soluble with technologies anticipated for spacecraft to be designed for Jupiter encounter. By contrast, the proton models are very diverse, fluxes and energies spanning several orders of magnitude even for those models based on physical considerations; this results from the absence of applicable data. However, even in the midrange of these models, the proton energies and fluxes would be severely hazardous to several spacecraft subsystems. It is therefore desirable to apply further technical consideration to the modeling of Jupiter's energetic proton population.
Discussion of some results of the effects of ionospheric irregularities on NASA satellite tracking and data acquisition operations. Ionospheric scintillation fading produced by irregularities has been observed at 136 MHz (vhf), 400 MHz (uhf), 1550 MHz (L-band) and 1700 to 2200 MHz (S-band). Details of these observations are presented. Vhf scintillation effects are evident in both auroral and equatorial regions. Fading effects decrease with increasing radio frequency in the auroral region. The same frequency dependence for fading is not observed in the equatorial region. Although there is a seasonal and diurnal character to scintillation in the equatorial region, fading effects are usually more severe than in the auroral region for a given radio frequency. Space diversity measurements indicate that reasonable solutions for vhf telemetry problems are available for either region. Space diversity should provide a solution for microwave frequencies as well. Ionospheric fading amplitude for 1700 MHz is relatively small in the auroral region. In the equatorial region amplitude fading levels for 1550-MHz signals from ATS-5 are often much larger than expected. Observations of the Apollo Lunar Surface Experiment Package (ALSEP) operating at 2300 MHz observed near the geomagnetic equator show fading peaks in excess of 15 dB.
Telemetry bands are being reassigned to UHF at 1500 and 2200 MHz. Conversion primarily requires changes in equipment used in RF link, while many of same subcarrier oscillators, mixer amplifiers, and frequency discriminators can be used.