EcoSAR Technology IGARSS Presentation.pdf

Goddard Space Flight Center

ESTO-IIP 2011-2014


mailto:[email protected]�


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Introduction• EcoSAR is a new radar development at NASA/Goddard Space Flight Center for the measurements of terrestrial ecosystem structure and biomass.

• The EcoSAR measurements will directly support science requirements for the study of the carbon cycle and its relationship to climate change.

• EcoSAR will use Electronic Beam Steering and Digital Beamforming to implement Polarimetric and Interferometric Synthetic Aperture Radar (SAR) .

ESTO-IIP 2011-2014


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Science QuestionHow are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's carbon budget, ecosystem sustainability, and biodiversity?

The CARBON CYCLE. Carbon in the atmosphere is a controlling factor on climate and hence on ecological productivity and the sustainability of life.

Science Driver

EcoSAR will acquire unique measurements that will help us quantify carbon in vegetation, and how it is changing.


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Instrument Science RationaleP-band SAR penetrates vegetation structure allowing the sensing of the entire canopy volume and woody density. Such measurements can be directly related to aboveground biomass.SAR measurements can be performed in most weather conditions and provide the capability of mapping the vegetation cover and changes due to natural and human-induced disturbances frequently.

Polarimetric radar is sensitive to the shape, orientation and dielectric properties of scatterers and allows the identification and separation of the scattering mechanisms.


HHHV

Pol-InSAR height measurements: - InSAR is highly sensitive to the spatial variability of

vertical structure parameters and enables accurate 3D localization of the scattering center.

- EcoSAR will implement Pol-InSAR techniques to provide measurements that will allow us to separate ground from canopy and derive canopy height and to investigate the 3-D structure of volume scatterers .

HV scattering phase center

HH scattering phase center


EcoSAR Main Science objectives• EcoSAR instrument will quantify:

– Biomass– Canopy and Surface Height– Ecosystem structure and extent – Disturbance and recovery

• Science Goals– Height with 1 m accuracy from single-Pass

Polarimetric Interferometry– Biomass up to 200 Mg/ha from PolSAR

measurements alone – Resolution of 0.75 m in range

• Additional Science :– Solid Earth: deformation and subsidence– Cryo: ice sheet and permafrost depth– Hydro: surface water extent, salinity, soil

moisture– Applications: soil/canopy penetration for

archaeological studies


EcoSAR Architecture

Radar Transceivers, Antenna Subarrays, and Synthesizer/Acquisition and Processor (SAP) Unit

• 18 transceivers support polarimetric and interferometric measurements.

• Each antenna consists of 9 dual polarization, high bandwidth subarrays.

• 18 Waveform generators directly synthesize P-band signals with up to 200 MHz bandwidth.

•18 Receivers will sample the radar returns directly.

•Synthesizer/Acquisition and Processor system will be designed around the Xilinx Virtex 5 FPGA.

• Digital I&Q demodulation, decimation and filtering will be performed on board.

• Processor supports subsequent onboard radar processing (e.g., digital beamforming, SAR image formation, multi-look, etc…)

Antennas

SAP SBIR Prototype by IAI

Goddard Space Flight CenterEcoSAR System description

EcoSAR will fly on the NASA P3 airplane based at Wallops Flight Facility

Center Frequency 435 MHz Pulse Length 1 usec – 50 usecMaximum Bandwidth 200 MHz Array Peak Power 40 WattsPolarization HH, VV, VH,HV PRF 100 Hz – 10 KHzPolarization Isolation < 25 dB Swath 4 km – 8 kmNoise Equivalent σo - 41 dB * Finest Range Resolution 0.75 mTotal Number Channels 36 Single Look Azimuth

Resolution0.5 m

Interferometric baseline 25 m Vertical Accuracy < 5 m


EcoSAR Concept


Height (m)

Example of SAR and InSARusing DBSAR (L-band) measurements


Swath 2

Flight Path

rx

ry

θ2

Antenna

Swath 1

rx

ry

θ1

FLIGHT

TRACK

Example of multiple beam technique


EcoSAR Resolution

Low Resolution

Medium Resolution

High Resolution

Slant Ground

Azimuth (Cross Range) Resolution

0.5 m (single look)

25 m 44 m

5 m 8.7 m

0.75 m 1.3 m

Range Resolution


3 m

1.0 m

EcoSAR Antennas

Subarray S11 and S22 parameters Cross coupling is below -80dB

Antenna ParametersType Micro-Strip PatchCenter Frequency 435 MHzBandwidth 200 MHzGain 19 dBArea 3 m2

Polarization Dual, linearCross Polarization Isolation < 25 dBNumber of Sub Arrays 9Total Number of Elements 27

Three-element subarray

Each antenna array mounts the P3 aircraft wing

The EcoSAR antenna arrays will allow to steer the beam across track


Year 1

Definition of the EcoSAR science and system requirements

Antenna Arrays Design and fabrication

Radar Electronics Unit Design and fabrication

Year 2

Completion of Waveform generator/data system

Testing and programming of waveform generator/data system

Radar Electronics evaluation, testing and initial assembly.

Full system integration and testing in laboratory and in anechoic chamber.

Year 3

Installation and test flight operation of the system on the NASA P-3 aircraft

Validation of EcoSAR test flight data sets

Field Campaign 1 New Hampshire and Maine

Field Campaign 2 Costa Rica

Science Retrievals from EcoSAR campaigns

Schedule and Milestone

Goddard Space Flight CenterConcluding Remarks

• Our team has successfully completed the design of prototype dual polarized wideband P-band antenna element. A full array simulation is underway.

• The aerodynamic analysis on antenna structure has been performed.

• The radar transceiver schematic has been completed. Components specifications and availability are currently being investigated.

• The processor development is scheduled to begin in August 2011.


End of Presentation

EcoSAR Technology IGARSS Presentation.pdf

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