Engineering topics
Treuhaft, R.
Publications and source records attributed to Treuhaft, R..
The Information Content of Multibasline Polarimetric Radar Interferometry
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The Vertical Structure of Vegetated Land Surfaces from Interferometric and Polarimentric Radar
This paper describes the estimation of vertical-structure parameters from combined interferometric and polarimetric radar data.
Realistic Symmetries: How They Determine the Accuracy of Interferometry + Polarimetry for Characterizing Vegetated Land Surfaces
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Recent Advances in Wide-Band Polarimetric and Multi-Baseline Interferometry
This paper describes the first fixed-baseline polarmetric interferometry, achieved with Jet Propulsion Laboratory's (JPL) TOPSAR radar with co- and cross-polarized signals.
A Unified Analysis of Radar Interferometry and Polarimetry for the Estimation of Forest Parameters
In this paper, interferometry will mean the acquisition and cross-correlation of complex signals at two different ends of a baseline, but with the same receive and transmit polarization at each end.
A Hybrid Algorithm for Estimating Boreal Forest Canopy Parameters from Polarimetric and Interferometric SAR
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Astrometry VLBI in Space (AVS
A proposed new space radio astronomy mission for astrometry is described. The Astrometry VLBI (very long baseline) in Space (AVS) nominal mission includes two identical spacecraft, each with a 4-m antenna sending data to a 70-m ground station. The goals of AVS are improving astrometry accuracy to the microarcsecond level and improving the accuracy of the transformation between the inertial radio and optical coordinate reference frames.
Toward 10-Milliarcsecond Infrared Astrometry
Infrared astometry at the 10-milliarcsecond (mas) level is applicable to experiments in stellar evolution astronomy, solar system dynamics, relativistic gravitation, and deep space laser tracking. We are pursuing astrometry with the U.C. Berkeley Infrared Spatial Interferometer (ISI) on Mt. Wilson to demonstrate a 10-mas capability for tracking stellar and solar system objects. Astrometric data from the ISI, taken and analyzed over the last 5 years, have shown that instrumental and atmospheric effects limit current demonstrations.
Evaluation of the table Mountain Ronchi telescope for angular tracking
The performance of the University of California at San Diego (UCSD) Table Mountain telescope was evaluated to determine the potential of such an instrument for optical angular tracking. This telescope uses a Ronchi ruling to measure differential positions of stars at the meridian. The Ronchi technique is summarized and the operational features of the Table Mountain instrument are described. Results from an analytic model, simulations, and actual data are presented that characterize the telescope's current performance. For a star pair of visual magnitude 7, the differential uncertainty of a 5-min observation is about 50 nrad (10 marcsec), and tropospheric fluctuations are the dominant error source. At magnitude 11, the current differential uncertainty is approximately 800 nrad (approximately 170 marcsec). This magnitude is equivalent to that of a 2-W laser with a 0.4-m aperture transmitting to Earth from a spacecraft at Saturn. Photoelectron noise is the dominant error source for stars of visual magnitude 8.5 and fainter. If the photoelectron noise is reduced, ultimately tropospheric fluctuations will be the limiting source of error at an average level of 35 nrad (7 marcsec) for stars approximately 0.25 deg apart. Three near-term strategies are proposed for improving the performance of the telescope to the 10-nrad level: improving the efficiency of the optics, masking background starlight, and averaging tropospheric fluctuations over multiple observations.