Imaging Radars: system architectures and technologies G. Angino, A. Torre Frascati, INFN, 2011, November 28th

All rights reserved © 2011, Thales Alenia Space Scope The potentiality of multichannel SAR to provide wide-swath and high resolution at the same time, has attracted increased interest among remote sensing community  The scope of this paper is to address some of the architectural and technological aspects related to the implementation of a multichannel receiver for a multi-beam SAR, with the objective to provide some solutions for different configurations with increased complexity  A further point is the exploitation of the multichannel configuration for the implementation of very high resolution modes

All rights reserved © 2011, Thales Alenia Space Next Generation SAR Challenges  Spaceborn SAR systems are now no more “experiments” but are fielded for operational use.  Specialized systems optimized for different application:  Earth Resource Exploitation  Ship Traffic Monitoring  Land Use  Disaster Prevention and Management  Security/Intelligence  and many others…  Sophisticated features required  Polarimetry  MTI  Very wide swath  Very high resolution

All rights reserved © 2011, Thales Alenia Space Space-based observation The applications 4 Civilian applications Defence applications Territory Surveillance Intelligence Target detection, classification and recognition Decision making support (C 4 I) Mission preparation Risk Management Environment Landscape ecology Land use monitoring Science Homeland security Cartography Digital Elevation Modelling

All rights reserved © 2011, Thales Alenia Space Optical Image Cranes Multi-temporal observation (one more ship) Railway 5 SAR allows quick detection of metallic artifacts, ships, and docking infrastructures High resolution applications

All rights reserved © 2011, Thales Alenia Space Wide Area applications

All rights reserved © 2011, Thales Alenia Space User Needs  Very High Geometric Resolution  Wider bandwidths to achieve range resolution  r = c/2B sin   Larger Synthetic Aperture for azimuth resolution  Spotlight  Multi-beam  Increased swath coverage  Swath width is limited by range ambiguity  SCANSAR mode allows to enlarge the swath at the expense of azimuth resolution These two performances impose contrasting requirements to the SAR system. The usage of multiple receive beams is a promising technique which can solve this contrast, at the expenses of system complexity

All rights reserved © 2011, Thales Alenia Space User needs – Imaging Modes

All rights reserved © 2011, Thales Alenia Space Imaging Radar Performance

All rights reserved © 2011, Thales Alenia Space Digital Beam Forming  Capability to synthesize several simultaneous beams in the azimuth direction by means of digital beam- forming (DBF) allows to couple the high azimuth resolution typical of the spotlight mode with the continuous coverage of the stripmap operation.  DBF for future SAR payloads requires an advanced architectural design assuring with a modular architecture On-board data processing and storage Modular HW & SW partitioning Multichannel digital core Multi-Gbps I/F (ASIC,FPGA,DSP,RAM)

All rights reserved © 2011, Thales Alenia Space DBF for Spaceborne SAR The Elevation DBF compensates the reduced transmit-gain with a large receive-gain The Azimuth DBF allows for a fine azimuth resolution at a reduced PRF by means of Multi-Channel Sampling of the signal-phase azimuth-spectrum

All rights reserved © 2011, Thales Alenia Space Multichannel Architecture  A multi-channel receiver is needed to handle multiple beams and offers the potential two handle very high bandwidth in frequency displaced mode  This architecture offers the advantage that the same standard building blocks can be used in different quantities and mix to fit a wide range of applications.  Multi-channel architecture can operate either in  frequency displaced mode (each channel handles a share of the overall bandwidth, merged afterwards in on-ground processing), or in  space displaced mode for multi-beam application

All rights reserved © 2011, Thales Alenia Space  Single conversion, sampling at S-band IF  Optical data link with digital backend (digital filtering and decimation)  Flexible LO generator and Flexible Switch Matrix to allow reconfiguration Multichannel Architecture

All rights reserved © 2011, Thales Alenia Space  The DPE shall receive the individual receive channels from the antenna (following digitization and first level processing performed by dedicated Integrated Pre- Processing Modules (IPP))  The Integrated Pre-Processing consists of a building block housed in a dedicated mechanical module performing the following functions:  Digitalisation of the incoming IF echo  Extraction of the I/Q channels  Band-limiting filtering and (if needed) data decimation DBF processing

All rights reserved © 2011, Thales Alenia Space  Pre processing section in charge of: Echo Digitisation Extraction of baseband components Bandpass filtering and decimation Data compression and formatting Integrated Pre-Processing Section

All rights reserved © 2011, Thales Alenia Space Digital processing element (DPE) DPE main processing task is beam synthesis

All rights reserved © 2011, Thales Alenia Space  The processing nodes are fully programmable and can perform virtually any computation function running application-specific software.  Required processing power can be achieved by simply using more or less modules. DPE Implementation: Integrated Digital Core  Integrated Pre-Processors based (for the development phase) on Xilinx Virtex-5 FPGAs  HIGH-Performance processing nodes based on PowerPC 7448 CPUs  16 to 32 GByte DRAM mass memory

All rights reserved © 2011, Thales Alenia Space THANK YOU FOR YOUR ATTENTION !