Venusian Surface Roughness Inversion Using Two Scale Approximation
Magellan was launched on May 4, 1989 on the Shuttle Atlantis in order to achieve global imaging of the Venus surface.
Venus radar mapping surface morphology electrical ↗
Engineering topics
Rodriguez, E.
Publications and source records attributed to Rodriguez, E..
A Fast Algorithm for Altimeter Waveform Retracking with Appications to the Geosat Altimeter
In this paper, we present a new technique for faster than real time estimation for height from altimeter waveforms using modest computer resources.
waveform data ocean altimeter ocean surface height↗
Assessment of the Topex Altimeter Performance Using Waveform Retracking
In order to assess the accuracy of the TOPEX altimeter data, we have reprocessed the raw altimeter waveform data using more sophisticated algorithms than those implemented in the altimeter hardware.
TOPEX↗
Estimation of of the Electromagnetic Bias from Retracked TOPEX Data
We examine the EM bias by using retracked TOPEX altimeter data.
TOPEX↗
Theory and design of interferometric synthetic aperture radars
A derivation of the signal statistics, an optimal estimator of the interferometric phase, and the expression necessary to calculate the height-error budget are presented. These expressions are used to derive methods of optimizing the parameters of the interferometric synthetic aperture radar system (InSAR), and are then employed in a specific design example for a system to perform high-resolution global topographic mapping with a one-year mission lifetime, subject to current technological constraints. A Monte Carlo simulation of this InSAR system is performed to evaluate its performance for realistic topography. The results indicate that this system has the potential to satisfy the stringent accuracy and resolution requirements for geophysical use of global topographic data.
Rodriguez, E.↗
Global digital topography mapping with a synthetic aperture scanning radar altimeter
Global digital topography data of the land surface is of importance in a variety of geoscientific and application disciplines. Such a database, with a spatial resolution of 150 to 500 m and height accuracy of 5 m or better can be acquired from an orbiting platform using a synthetic aperture scanning radar altimeter. Near-global coverage can be achieved within 14 days from an orbiting platform in a polar or near-polar orbit.
Elachi, C.↗
Wide swath ocean topography mapping with interferometric altimeters
An interferometric radar altimeter is proposed to provide wide-swath high-resolution ocean topography. Several system design issues of such an interferometric altimeter are presented. Tradeoffs between processing of the interferometric signal using the so-called amplitude approach and the so-called phase approach are shown. The systematic errors associated with uncertainties in the interferometer baseline and the attitude of interferometer orientation are also discussed. Described is an approach using the measurements at orbit cross-over regions, together with the topography measurements from a traditional nadir-looking altimeter that are not contaminated by the baseline and attitude noises. Preliminary simulation results show that such an approach can generate an acceptable error level if the ocean surface does not change appreciably between the observations.
Rodriguez, E.↗
Global digital topography mapping using a scanning radar altimeter
The conceptual design of a Scanning Radar Altimeter system capable of collecting less than 300-m spatial and less than 3-m height resolution digital topography data for the entire globe, from an orbital platform, is presented. A 37-GHz frequency SRA system is used to achieve the requisite resolution while reducing antenna length in the along-track dimension. Near-global coverage in a short time period is obtained by scanning the antenna beam cross-track, in a swath of about 100 km. Attention is given to the algorithm that will be used to retrieve pixel height from the return waveform.
Elachi, C.↗
Evaluation of land altimetry systems
The performance of land altimetry systems was studied by simulating radar returns from modeled and actual topographic data. Four different algorithms were considered and contrasted using a set of performance criteria. A potential definition of the horizontal resolution of a radar altimeter was evaluated. Results indicate that the peak-power and threshold algorithms are more affected by noise and changes in surface topography than the centroid and half-energy algorithms. The centroid and half-energy algorithms can provide better spatial resolutions for the altimetric measurements.
Rodriguez, E.↗
High speed reaction wheels for satellite attitude control and energy storage
The combination of spacecraft attitude control and energy storage (ACES) functions in common hardware, to synergistically maintain three-axis attitude control while supplying electrical power during earth orbital eclipses, allows the generation of control torques by high rotating speed wheels that react against the spacecraft structure via a high efficiency bidirectional energy conversion motor/generator. An ACES system encompasses a minimum of four wheels, controlling power and the three torque vectors. Attention is given to the realization of such a system with composite flywheel rotors that yield high energy density, magnetic suspension technology yielding low losses at high rotational speeds, and an ironless armature permanent magnet motor/generator yielding high energy conversion efficiency.
Studer, P.↗