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You searched for +publisher:"University of Oklahoma" +contributor:("Torres, Sebastian"). Showing records 1 – 2 of 2 total matches.

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University of Oklahoma

1. Nai, Feng. On the Potential of Adaptive Beamforming for Phased-Array Weather Radar.

Degree: PhD, 2017, University of Oklahoma

As the Weather Surveillance Radar 1988 Doppler network reaches the end of its expected life, a network of multifunction phased-array radars (MPAR) supporting both aircraft and weather surveillance missions has been proposed. A phased-array system should match the sensitivity, spatial resolution, and data quality of the WSR-88D while having a update time of 60 seconds for weather surveillance. Since an MPAR system must complete both weather and aircraft surveillance missions, the update time reduction provided by having multiple faces is insufficient to achieve the desired 60 second update time for weather surveillance. Therefore, it is likely that multiple simultaneous beams would be needed per face to meet the timeline requirements. An approach to achieve multiple receive beams is to use a spoiled transmit beam and to form a cluster of simultaneous receive beams. However, a significant challenge for this approach is the potential of high sidelobe levels in the two-way radiation pattern, which can result in significantly biased estimates of the radar variables in situations where the signal power has large spatial variation. This dissertation proposes an adaptive beamspace algorithm designed for phased-array weather radar that utilizes a spoiled transmit beam and a cluster of simultaneous receive beams to achieve the desired timeline. Taking advantage of the adaptive algorithm's ability to automatically adjust sidelobe levels to match the scene, the high-sidelobe problem associated with a spoiled transmit beam is mitigated. Through extensive simulations, it is shown that adaptive beamspace processing can produce accurate and calibrated estimates of weather radar variables. Furthermore, it is demonstrated that the adaptive beamspace algorithm can automatically reject interference signals and reduce their impact on the radar-variable estimates. Additionally, it is shown that, despite higher sidelobe levels, the adaptive beamspace algorithm can perform similarly to a conventional system based on a dish antenna in terms of biases when reflectivity gradients are present. Finally, the adaptive beamspace algorithm is shown to compare favorably to some alternative solutions that can also achieve the desired MPAR timeline requirement while preserving data quality. Advisors/Committee Members: Palmer, Robert (advisor), Torres, Sebastian (advisor), Goodman, Nathan (committee member), Yu, Tian-You (committee member), Wang, Xuguang (committee member).

Subjects/Keywords: Adaptive Beamforming; Phased-Array Radar; Weather Radar; Beamspace

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Nai, F. (2017). On the Potential of Adaptive Beamforming for Phased-Array Weather Radar. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/48164

Chicago Manual of Style (16th Edition):

Nai, Feng. “On the Potential of Adaptive Beamforming for Phased-Array Weather Radar.” 2017. Doctoral Dissertation, University of Oklahoma. Accessed March 08, 2021. http://hdl.handle.net/11244/48164.

MLA Handbook (7th Edition):

Nai, Feng. “On the Potential of Adaptive Beamforming for Phased-Array Weather Radar.” 2017. Web. 08 Mar 2021.

Vancouver:

Nai F. On the Potential of Adaptive Beamforming for Phased-Array Weather Radar. [Internet] [Doctoral dissertation]. University of Oklahoma; 2017. [cited 2021 Mar 08]. Available from: http://hdl.handle.net/11244/48164.

Council of Science Editors:

Nai F. On the Potential of Adaptive Beamforming for Phased-Array Weather Radar. [Doctoral Dissertation]. University of Oklahoma; 2017. Available from: http://hdl.handle.net/11244/48164


University of Oklahoma

2. Schvartzman, David. Signal Processing Techniques and Concept of Operations for Polarimetric Rotating Phased Array Radar.

Degree: PhD, 2020, University of Oklahoma

The Weather Surveillance Radar 1988 Doppler (WSR-88D) network has been operational for over 30 years and is still the primary observational instrument employed by the National Weather Service (NWS) forecasters to support their critical mission of issuing severe weather warnings and forecasts in the United States. Nevertheless, the WSR-88Ds have exceeded their engineering design lifespan and are projected to reach the end of operational lifetime by 2040. Technological limitations may prevent the WSR-88D to meet demanding functional requirements for future observational needs. The National Oceanic and Atmospheric Administration (NOAA) has started considering radar systems with advanced capabilities for the eventual replacement of the WSR-88D. Unique and flexible capabilities offered by Phased Array Radar (PAR) technology support the required enhanced weather surveillance strategies that are envisioned to improve the weather radar products, making PAR technology an attractive candidate for the next generation of weather radars. If PAR technology is to replace the operational WSR-88D, important decisions must be made regarding the architecture that will be needed to meet the functional requirements. A four-faced planar PAR (4F-PAR) is expected to achieve the requirements set forth by NOAA and the NWS, but deploying and maintaining an operational network of these radars across the U.S. will likely be unaffordable. A more affordable alternative radar system is based on a single-face Rotating PAR (RPAR) architecture, which is capable of exceeding the functionality provided by the WSR-88D network. This dissertation is focused on exploring advanced RPAR scanning techniques in support of meeting future radar functional requirements. A survey of unique RPAR capabilities is conducted to determine which ones could be exploited under an RPAR Concept of Operations (CONOPS). Three capabilities are selected for further investigation: beam agility, digital beamforming, and dwell flexibility. The RPARs beam agility is exploited to minimize the beam smearing that results from the rotation of the antenna system over the collection of samples in the coherent processing interval. The use of digital beamforming is investigated as a possible way to reduce the scan time and/or the variance of estimates. The RPAR's dwell flexibility capability is explored as a possible way to tailor the scan to meteorological observations with the goal of improving data quality. Three advanced RPAR scanning techniques are developed exploiting these capabilities, and their performance in support of meeting the radar functional requirements is quantified. The proposed techniques are implemented on the Advanced Technology Demonstrator (ATD), a dual-polarization RPAR system at the National Severe Storms Laboratory (NSSL) in Norman, OK. Data collection experiments are conducted with the ATD to demonstrate the performance of the proposed techniques for dual-polarization observations. Results are verified by quantitatively comparing fields of radar-variable… Advisors/Committee Members: Yu, Tian-You (advisor), Torres, Sebastian (committee member), Yeary, Mark (committee member), Salazar-Cerreno, Jorge (committee member), Wang, Ying (committee member).

Subjects/Keywords: Weather Radar; Polarimetric Phased Array Radar; Signal Processing; Concept of Operations; Digital Beamdorming

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Schvartzman, D. (2020). Signal Processing Techniques and Concept of Operations for Polarimetric Rotating Phased Array Radar. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/326580

Chicago Manual of Style (16th Edition):

Schvartzman, David. “Signal Processing Techniques and Concept of Operations for Polarimetric Rotating Phased Array Radar.” 2020. Doctoral Dissertation, University of Oklahoma. Accessed March 08, 2021. http://hdl.handle.net/11244/326580.

MLA Handbook (7th Edition):

Schvartzman, David. “Signal Processing Techniques and Concept of Operations for Polarimetric Rotating Phased Array Radar.” 2020. Web. 08 Mar 2021.

Vancouver:

Schvartzman D. Signal Processing Techniques and Concept of Operations for Polarimetric Rotating Phased Array Radar. [Internet] [Doctoral dissertation]. University of Oklahoma; 2020. [cited 2021 Mar 08]. Available from: http://hdl.handle.net/11244/326580.

Council of Science Editors:

Schvartzman D. Signal Processing Techniques and Concept of Operations for Polarimetric Rotating Phased Array Radar. [Doctoral Dissertation]. University of Oklahoma; 2020. Available from: http://hdl.handle.net/11244/326580

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