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34 results on '"Loria, Eric"'

3. Distributed Aperture Radar Tomographic Sensors (darts) to Map Surface Topography and Vegetation Structure

Author

Chung, Soon-Jo, Capuano, Vincenzo, Matsuka, Kai, Anderson, Matthew, Chahat, Nacer, Focardi, Paolo, Haynes, Mark, Beauchamp, Robert, Clark, Duane, Prager, Samuel, Hawkins, Brian P, Ahmed, Razi, Loria, Eric, Ragan, James, Seker, Ilgin, and Lavalle, Marco

Abstract

Distributed Aperture Radar Tomographic Sensors (DARTS)is a mission concept being studied at the NASA Jet PropulsionLaboratory in collaboration with the California Institute ofTechnology to enable global and repeated imaging of surfacetopography and three-dimensional vegetation structure usingsingle-pass tomographic SAR technique. The observing systemconsists of a distributed formation of multiple small syntheticaperture radar platforms deployed in space with variabledistances to achieve look angle diversity and sensitivityto the vertical distribution of vegetation components. Ourgoal is to identify the optimal system configuration startingfrom documented community needs and mature the criticaltechnologies that lead to a viable implementation of DARTS.Here, we provide an overview of DARTS and describe ourapproach for designing and demonstrating single-pass SARtomographic systems as part of an on-going funded NASA Instrument Incubator Program effort.

Published
2021

7. Improved Orbit Determination of the Cygnss Satellites and its Application to Gnss-R Ocean Altimetry

Author

Conrad, Alex, Axelrad, Penina, Zuffada, Cinzia, Haines, Bruce, O’Brien, Andrew, and Loria, Eric

Abstract

The accuracy of spaceborne ocean surface altimetry depends on precise knowledge of the altimeter satellite orbit. Previous studies of the potential utility of CYGNSS GNSS Reflectometry (GNSS-R) measurements for ocean altimetry have identified its orbit error as a limiting factor. To address this, a recent firmware upgrade to the CYGNSS satellites have enabled the downlink of additional GPS raw measurements from its navigation receiver and increased numerical precision in open-loop GNSS-R tracking information. In this paper, we present improvements to the accuracy of both the orbit determination and the ocean surface height retrievals as a result of these recent upgrades. JPL’s GipsyX software is used to process 120 days of GPS navigation measurements for one of the 8 CYGNSS satellites. Incorporating high fidelity dynamic models and antenna group delay correction, daily orbit overlaps throughout the period show mean RMS differences of 3 cm in height, 7 cm in cross-track, and 10 cm in along-track. Applying these new orbits reduced the standard deviation of retrieved surface height anomalies. When spatially averaged, the sea surface height anomalies were reduced from 1.0 m to 0.8 m. Further improvements are expected using new ionospheric corrections and re-tracking methods currently in development.

Published
2020

14. Comparison of SAR and CYGNSS Surface Water Extent Metrics

Author

Chapman, Bruce D., primary, Russo, Ilaria Mara, additional, Galdi, Carmela, additional, Morris, Mary, additional, di Bisceglie, Maurizio, additional, Zuffada, Cinzia, additional, Downs, Brandi, additional, Lavalle, Marco, additional, Loria, Eric, additional, and O'Brien, Andrew J., additional

Published
2022
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17. Distributed Aperture Radar Tomographic Sensors (DARTS) to Map Surface Topography and Vegetation Structure

Author

Lavalle, Marco, primary, Seker, Ilgin, additional, Ragan, James, additional, Loria, Eric, additional, Ahmed, Razi, additional, Hawkins, Brian P., additional, Prager, Samuel, additional, Clark, Duane, additional, Beauchamp, Robert, additional, Haynes, Mark, additional, Focardi, Paolo, additional, Chahat, Nacer, additional, Anderson, Matthew, additional, Matsuka, Kai, additional, Capuano, Vincenzo, additional, and Chung, Soon-Jo, additional

Published
2021
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18. State of the Art in GNSS-R Capabilities Over Inland Waters

Author

Zuffada, Cinzia, primary, Downs, Brandi, additional, Russo, Ilaria Mara, additional, Loria, Eric, additional, O'Brien, Andrew, additional, Galdi, Carmela, additional, di Bisceglie, Maurizio, additional, Zavorotny, Valery, additional, Lavalle, Marco, additional, and Morris, Mary, additional

Published
2021
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23. Next Generation GNSS-R Instrument

Author

Ruf, Christopher, primary, Backhus, Roger, additional, Butler, Tim, additional, Chen, Chi-Chih, additional, Gleason, Scott, additional, Loria, Eric, additional, McKague, Darren, additional, Miller, Ryan, additional, O'Brien, Andrew, additional, and van Nieuwstadt, Line, additional

Published
2020
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34. Investigation of Coherent Reflections in GNSS-R using CYGNSS

Author

Loria, Eric Andrew

Subjects
Electrical Engineering, Computer Engineering, GNSS Reflectometry, Remote Sensing, GPS, Coherent Reflection, GNSS, wind measurement, adaptive signal processing
Abstract

Global Navigation Satellite System Reflectometry (GNSS-R) is a remote sensing technique that uses reflected GNSS signals to make measurements of geophysical properties of the Earth's surface. The significant roughness of typical ocean and land surfaces at L-band frequencies commonly result in diffusely scattered GNSS reflections. However, it has been observed that the surfaces of lakes, rivers, wetlands, and other inland water bodies are often sufficiently smooth to produce coherent reflections. Coherent reflections are of particular interest for remote sensing due to their high reflected power, fine spatial resolution, and phase information. Utilizing these reflections enables a unique capability to monitor the global surface water distribution underneath rain, clouds, and dense vegetation. To take full advantage of coherent reflections and best retrieve geophysical information, it is necessary to develop new scattering models, perform simulation studies, and understand how future GNSS-R receivers can be optimized to receive these types of signals. Until now, a comprehensive investigation of this type had not been undertaken. In this work, an electromagnetic scattering model is developed for coherent GNSS reflections over complex scenes with a number of varying surface parameters. The model is utilized to evaluate the accuracy of current water extent retrieval approaches and to propose a novel measurement of wind vector and wave heights from inland waters. Finally, two new algorithms are proposed to improve the science value of coherent GNSS reflections in future GNSS-R instruments.

Published
2020

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