Engineering topics

Schultz, S.

Publications and source records attributed to Schultz, S..

5 records

NASA NTRS1988

AIS radiometry and the problem of contamination from mixed spectral orders

The spectral radiance of test areas under solar illumination is ascertained in view of Airborne Imaging Spectrometer (AIS) data from Mono Lake, CA, establishing an atmospheric correction method for major absorbers on the basis of the spectrometric data themselves. The apparent low contrast of all atmospheric absorption bands leads to a study of contamination from overlapping spectral orders in the AIS data; this contamination is found unambiguously above 1500 nm with a magnitude that is a factor of 1.5-2.0 greater than the expected uncontaminated signal alone.

Conel, J. E.↗

NASA NTRS1986

Analysis of AIS radiometry with emphasis on determination of atmospheric properties and surface reflectance

Airborne Imaging Spectrometer data from Mono Lake, California, were studied in order to establish spectral radiance of test areas under solar illumination. The objective is to provide a method of atmospheric correction for major absorbers from the spectrometer data themselves. Crucial to the analysis is radiometric calibration of the instrument. Good agreement is found between calculated and measured radiances for uniform surface targets (beaches), but simulations of atmospheric properties with LOWTRAN lead to unreasonably low values of atmospheric precipitable water. Absorptions from carbon dioxide are not detected in the AIS data, but are strongly present in the LOWTRAN model. The apparent low contrast of all atmospheric absorption bands leads to a study of contamination from overlapping spectral orders in the AIS data. The suspected contamination is shown unambiguously to be present beyond approximately 1500 nm and consists of an extra radiance term including atmospheric bands from the delta/2 wavelength interval. A rigorous removal of the unwanted spectral contamination does not seem possible for any data taken in the rock mode. Rough estimates for tree-mode observations might be pieced together is a suitable after-the-fact radiometric claibration of the instrument can be formulated.

Conel, J. E.↗

NASA NTRS1986

Analysis of AIS radiometry at Mono Lake, California

Airborne imaging spectrometer (AIS) data were studied to establish absolute instrumental calibration and to provide atmospheric corrections. Good agreement is found between calculated and measured radiances for uniform surface targets (beaches), but simulations of atmospheric properties with LOWTRAN lead to unreasonably low values of atmospheric precipitable water. Absorptions from CO2 are not detected in the AIS data, but are strongly present in the LOWTRAN model. The apparent low contrast of all atmospheric absorption bands leads to a study of contamination from overlapping spectral orders in the AIS data. The suspected contamination is shown unambiguously to be present beyond 1500 nm. The magnitude remains uncertain. Spectral band filling at 1400 nm cannot be accounted for by order mixing because of the 800 nm blocking filter used. Rough corrections for short wavelength mode observations might be possible if an after-the-fact radiometric calibration of the instrument can be developed.

Conel, J. E.↗

NASA NTRS1985

Temperature dependence of the time decay of the magnetization in particulate media

The time decay of magnetization in commercial CrO2, gamma-Fe2O3, and Co-doped gamma-Fe2O3 tapes is investigated experimentally at temperatures 6, 50, 100, 200, 250, and 300 K. The decay is found to be linearly dependent on temperature in all four tapes tested, but when the curves are extrapolated to 0 K, there is a large finite intercept - in contrast to similar measurements on ferromagnetic materials and rocks.

Oseroff, S. B.↗

NASA NTRS1977

Simple waveguide reflection maser with broad tunability

The design and performance of a simple two-stage reflection maser for use between 9 and 10 GHz are described. The maser is used to improve the sensitivity of a transmission electron spin resonance spectrometer. A ruby-filled waveguide structure permits broad tunability and straightforward construction. All microwave components except the ruby section are at room temperature.

Flesner, L. D.↗