Rafael F. Rincon

NASA's L-Band Digital Beamforming Synthetic Aperture Radar

The Digital Beamforming Synthetic Aperture Radar (DBSAR) is a state-of-the-art L-band radar that employs advanced radar technology and a customized data acquisition and real-time processor in order to enable multimode measurement techniques in a single radar platform. DBSAR serves as a test bed for the development, implementation, and testing of digital beamforming radar techniques applicable to Earth science and planetary measurements. DBSAR flew its first field campaign on board the National Aeronautics and Space Administration P3 aircraft in October 2008, demonstrating enabling techniques for scatterometry, synthetic aperture, and altimetry.

Ecosar: A P- band digital beamforming Polarimetric Interferometric SAR instrument to measure ecosystem structure and biomass

In this paper we describe the EcoSAR concept, an airborne Polarimetric and Interferometric P- band SAR instrument that will provide unprecedented two- and three dimensional fine scale measurements of terrestrial ecosystem structure and biomass. These measurements are directly traceable to upcoming international radar missions and the National Research Councils Decadal Survey ecosystem measurement requirements.

The ecosystems SAR (EcoSAR) an airborne P-band polarimetric InSAR for the measurement of vegetation structure, biomass and permafrost

EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASAs Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

ECOSAR: P-band digital beamforming polarimetric and single pass interferometric SAR

EcoSAR is a state-of-the-art beamforming synthetic aperture radar (SAR) recently developed at the NASA/ Goddard Space Flight Center (GSFC) for the measurement of ecosystem structure and biomass. The airborne instrument operates at a center frequency of 435 MHz (P-band), and uses a multi-channel reconfigurable architecture to implement fully polarimetric and “single pass” interferometric measurements. The instrument architecture allows for the real-time configuration radar parameters, including center frequency, resolution, incidence angle, and number of beams, among others. The system is also designed to operate in standard or ping pong interferometric modes, and in full, orthogonal, or hybrid polarimteric modes. The instrument development was recently completed, and its first flight campaign successfully conducted in March 2014 over areas of Bahamas and Costa Rica.

The EcoSAR P-band Synthetic Aperture Radar

The EcoSAR instrument is a new concept in Synthetic Aperture Radar for the polarimetric and interferometric measurements of biomass and ecosystem structure. EcoSAR will employ a digital beamforming architecture, a highly capable digital wave-form generator and receiver system, and advanced dual-polarization array antennas with an interferometric baseline of 25 m on the NASA P3 aircraft.

Real-time beamforming synthetic aperture radar

This paper discusses the concept and design of a real-time Digital Beamforming Synthetic Aperture Radar (DBSAR) for airborne applications which can achieve fine spatial resolutions and wide swaths. The development of the DBSAR enhances important scientific measurements in Earth science, and serves as a prove-of-concept for planetary exploration missions. A unique aspect of DBSAR is that it achieves fine resolutions over large swaths by synthesizing multiple cross-track beams simultaneously using digital beamforming techniques. Each beam is processed using SAR algorithms to obtain the fine ground resolution without compromising fine range and azimuth resolutions. The processor uses an FPGA-based architecture to implement digital in-phase and quadrature (I/Q) demodulation, beamforming, and range and azimuth compression. The DBSAR concept will be implemented using the airborne L-Band Imaging Scatterometer (LIS) on board the NASA P3 aircraft. The system will achieve ground resolutions of less than 30 m and swaths of 10 km from an altitude of 8 km.

NASA's L-Band Imaging Scatterometer

The L-Band Imaging Scatterometer (LIS) is an airborne radar developed at NASA Goddard Space Flight Center which combines electronic beam steering and digital beamforming allowing the implementation of different scanning techniques. The LIS efforts are part of the RadSTAR initiative intended to develop the technology that will enable a combined radar/radiometer system that jointly uses a single, dual frequency antenna with cross-track scanning capabilities, but no moving parts. The new technology will enable single aperture measurements of important Earth Science Enterprise climate applications such as ocean salinity, soil moisture, sea ice, and surface water among others. The LIS instrument will be flown along with existing NASA Synthetic Thinned Array Radiometers (STAR) in order to prove the concept of coregistered data and to provide a prototype for a spaceborne, single aperture radar/radiometer system.

Waveform design for wideband beampattern and beamforming

This paper considers wideband beamforming and waveform design for transmission from advanced multiple channel radar systems. Hence, this paper describes the initial designs of a wideband transmit beamformer for a multi-channel high resolution radar, applicable to airborne and spaceborne radars. As a case study for this paper, we use the EcoSAR instrument developed by NASA Goddard Space Flight Center for the measurement of science parameters. The wideband EcoSAR employs two multi-channel antennas and full transmit and receive digital beamforming to generate high resolution images of the ground features. Maintaining a consistent beampattern when the bandwidth is approximately 50% of the center frequency is a challenge. Breaking this nexus relies on optimum beam weight design and accompanying waveform design; not merely the former as is typically done. The approaches of this paper have shown how the beampatterns can be maintained while meeting beam requirements.

Digital Beamforming Synthetic Aperture Radar (DBSAR) polarimetric operation during the Eco3D flight campaign

The Digital Beamforming Synthetic Aperture Radar instrument demonstrated its first polarimetric polarization operation during the Eco-3D flight campaign, on board the NASA P3 aircraft in the summer/fall 2011. The measurements acquired during the campaign are currently being used to demonstrate DBSARs science utility by providing critical information on vegetation structure needed to estimate vegetation biomass in order to advance our understanding of the carbon cycle.

RadSTAR L-band imaging scatterometer- performance assessment

L-band Imaging Scatterometer (LIS), developed at NASA/Goddard Space Flight Center as part of the RadSTAR initiative, is an airborne imaging radar that combines phased array technology and digital beam forming techniques for the measurement of important scientific parameters. The instrument operates at 1.26 GHz, horizontal polarization, and employs a real-time processor capable of synthesizing multiple beams over a scan range of +/-50 degrees. LIS was flight tested in May 2006 and in January 2007 on board of the NASA P3 aircraft over the Delmarva Peninsula, VA. In this paper we describe the RadSTAR system and present some preliminary analysis of the radar data collected during the test flights.