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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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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1969

Multipath performance of a TDRS system employing wideband FM VHF signals

An approximate theoretical analysis is presented for the effects of specular reflection multipath on the performance of a one-way tracking and data relay satellite-to-user link. The analysis pertains to the wideband FM system employing a sinusoidal subcarrier to achieve spectrum spreading. Bounds on multipath effects are derived for receivers with and without limiters and for data modulated on the carrier or the subcarrier. For data modulation, performance is evaluated in terms of an additive lowpass signal at the data detection filter. Doppler and range tracking performance is evaluated in terms of root-mean-square (RMS) error of carrier frequency in a carrier PLL and rms phase jitter in a subcarrier PLL.

Sohn, S. J.↗
NASA NTRS1971

On the selection of an optimum design point for phase-coherent receivers employing band-pass limiters.

Discussion of the optimum power allocation problem associated with the design of a phase-coherent receiver employing a bandpass limiter. A single channel system is treated in detail, and an optimization technique is proposed that makes use of up-to-date phase-locked loop and bandpass limiter theories recently contributed by Lindsey (1969) and Springett and Simon (1971). It is shown how this technique can be extended to a two-channel system.

Simon, M. K.↗
NASA NTRS1972

A low power X-ray diffractometer for soil analysis in remote locations employing a multiwire proportional counter detector array.

A low power X-ray powder diffraction system suitable for remote mineralogical analysis of lunar, planetary, or asteroid soils has been designed. A one Curie Fe-55 source provides a monochromatic X-ray beam of 5.9 keV. Seeman-Bohlin focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators, and storage flip-flops requiring only 3.5 milliwatts has been designed and tested. Total instrument power is less than 5 W.

Gregory, J. C.↗
NASA NTRS1972

Formulation procedure and spectral data for a coatings system optimally employing the high intrinsic reflectance of barium sulphate

The use of polyvinyl alcohol as a binder for barium sulphate does not allow the intrinsically high reflectance of this material in the near vacuum ultraviolet to be optimally employed. In an effort to better utilize this property, completely inorganic coatings systems are described, where from the intrinsically high reflectance of barium sulphate in this spectral region can be gotten. Potassium sulphate turns out to be the preferred binder. Compositions, formulating procedures, and application techniques are included. For completeness, absolute and relative reflectance data are included for intra- and intersystem comparisons.

Schutt, J. B.↗