4_IGARSS11_HRWS.ppt

685 views

Published on

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
685
On SlideShare
0
From Embeds
0
Number of Embeds
11
Actions
Shares
0
Downloads
22
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • - Let’s take a briefly look on the outline of the presentation. In the first part of the presentation it will be presented the actual context and the limitation that has motivated the study of a new approach based on the Adaptive Digital beam-Forming. Later on the different tools to better understand this approach are presented and finally the numerical results
  • In the actual context the remote sensing applications are demaning products with high resolution capabilities simulatenously with wide coverage. However, these are contardictory requirements. Inorder to overcome this limitation of the conventional SAR. It has been proposed a new technique that combines samrt antennas with multiple tx/rx antennas with digital signal processing. One of this approaches is the so called High Resolution Wide Swath combine with a digital beamforming technique SCORE. In this case the wider swath is obtained with a smaller tx antenna and a larger rx antenna compensate the reduced gain. The classical conflict between high resolution and wide swath is overcome using a multiple rx antenna in azimuth. The radiometric resolution is improved through a larger multi-channel antenna in elevation where a digital beam.forming technique SCORE allows to combine the signals and generate a sharp beam following the echo on the ground (with the maximum gain). The steering direction of SCORE corresponds to the acutal direction of arrival which is assumed to be a priori known, which is unique associated to the slant range or two-way time delay under the asumption of a spheical earth with no topography.
  • - Let’s take a briefly look on the outline of the presentation. In the first part of the presentation it will be presented the actual context and the limitation that has motivated the study of a new approach based on the Adaptive Digital beam-Forming. Later on the different tools to better understand this approach are presented and finally the numerical results
  • 4_IGARSS11_HRWS.ppt

    1. 1. Performance Investigation on the High-Resolution Wide-Swath SAR System Operating in Stripmap Quad-Pol and Ultra-Wide ScanSAR Mode DLR - Institut für Hochfrequenztechnik und Radarsysteme F. Bordoni , M. Younis, G. Krieger IGARSS 2011, 24-29 July, Vancouver, Canada
    2. 2. Outline <ul><li>Introduction </li></ul><ul><ul><li>HRWS (High-Resolution Wide-Swath) SAR (Synthetic Aperture Radar) System </li></ul></ul><ul><ul><li>Reference Parameters </li></ul></ul><ul><li>Stripmap, Quad-Pol (Quadrature Polarimetric) Mode </li></ul><ul><ul><li>Timing & Constraints </li></ul></ul><ul><ul><li>Proposed Solution </li></ul></ul><ul><ul><li>Performance: </li></ul></ul><ul><ul><ul><li>NESZ (Noise Equivalent Sigma Zero) </li></ul></ul></ul><ul><ul><ul><li>RASR (Range Ambiguity to Signal Ratio) </li></ul></ul></ul><ul><ul><ul><li>AASR (Azimuth Ambiguity to Signal Ratio) </li></ul></ul></ul><ul><li>ScanSAR Mode: Ultra-Width Swath </li></ul><ul><ul><li>Timing & Constraints </li></ul></ul><ul><ul><li>Proposed Solution </li></ul></ul><ul><ul><li>Performance (NESZ, RASR, AASR, Scalloping) </li></ul></ul>
    3. 3. Displaced Phase Center Antenna >> high spatial resolution Multichannel Antenna Wide transmit pattern >> wide swath R(t) nadir H orb SCORE algorithm >> high gain HRWS (High-Resolution Wide-Swath) SAR System The HRWS SAR system is conceived to overcome the conventional trade-off between resolution and swath width Current SAR: 1 m v.s. 10 km; 16 m v.s. 100 km HRWS: 1 m v.s. 70 km (stripmap single-pol) Digital Beamforming
    4. 4. <ul><li>Monostatic System </li></ul><ul><li>Planar phased array antenna </li></ul>HRWS Reference System Parameters 2 Tile 1 Tile 12 Tile ... Panel 1 Panel 7 Panel 2 ... 1,06 m 8,75 m Total Nr. TRMs (Transmit-Receive Modules) Elevation: 12 dig. chan. Azimuth: 7 dig. chan. 1,25 m 0,088 m Orbit Height: 520 km Antenna Tilt Angle: 34,3 deg RF Center Frequency: 9,6 GHz Pulse Bandwidth: 408 ÷ 194 MHz Processed Doppler bandwidth: 5950 Hz (stripmap) Averaged Tx Power: 2171 W Fully Polarimetric SCORE operation Tx patterns in az. and elev. by Phase Spoiling
    5. 5. HRWS Basic Performance The basic performance of the HRWS has been already investigated In Stripmap single-pol Mode: <ul><ul><li>6 subswaths cover the complete access range </li></ul></ul><ul><ul><li>Swath width: 70 - 80 km </li></ul></ul><ul><ul><li>Spatial resolution: 1 m x 1 m </li></ul></ul><ul><ul><li>NESZ < - 20.7 dB </li></ul></ul><ul><ul><li>RASR: < - 28 dB </li></ul></ul><ul><ul><li>AASR < - 26 dB </li></ul></ul>How performs the HRWS in Quad-Pol, ScanSAR Modes?
    6. 6. Stripmap Quad-Pol: Timing Diagram Transmit alternately vertical & horizontal linear polarized pulses  Double PRF (Pulse Repetition Frequency) Single-pol Quad-pol Timing Diagram Spatial resolution: 1 m x 1 m Nr. Subswaths: 12 Swath width smaller: 20 - 50 km Spatial resolution: 1 m x 1 m Nr. Subswaths: 6 Subswath width: 70 - 80 km PRF: 1650 – 1780 Hz PRF double: 3400 – 3800 Hz
    7. 7. Requirements & Constraints <ul><li>Multichannel: Less degrees of freedom in the PRF choice (PRF uniformity*) </li></ul><ul><ul><li>AASR (particularly low) </li></ul></ul><ul><ul><li>NESZ (multichannel processing) </li></ul></ul><ul><li>Flexibility Design Elevation Patterns </li></ul><ul><ul><li>Mailobe @ subswath width (RASR, NESZ) </li></ul></ul><ul><ul><li>Low sidelobe level (RASR) </li></ul></ul>Severe requirements and constraints characterize the Quad-pol mode <ul><li>Quad-pol: High PRF </li></ul><ul><ul><li>RASR (critical especially in Cross-Pol ) </li></ul></ul>*PRF matched to the antenna length and No. of apertures > regular sampling in azimuth results
    8. 8. - 19 dB <ul><li>RASR Cross-pol < - 19 dB </li></ul>Elev. pattern design crucial to meet the RASR requirements in Cross-Pol Hamming vs. Uniform: improvement in far range - 4 dB near range far range NESZ RASR Pattern Design & RASR in Cross-Pol  Tx Phase Spoiling and uniform tapering (mainlobe  subswath width) - - - Rx Hamming window (  side lobe level)
    9. 9. Stripmap Quadpol: RASR in Co-Pol & NESZ -27 dB - 19,5 dB <ul><li>RASR Co-Pol < - 27 dB </li></ul><ul><li>NESZ < - 19,5 dB </li></ul>Range Ambiguity Signal Ratio: Co-Pol Noise Equivalent Sigma Zero (spatial resolution: 1 m x 1m)
    10. 10. Stripmap Quadpol: Azimuth Performance <ul><li>Az. Res. < 1,1 m </li></ul><ul><li>AASR < - 30,5 dB </li></ul>Azimuth Resolution Azimuth Ambiguity Signal Ratio 1,1 m - 30,5 dB
    11. 11. Swath width of 375 km  complete imaging of the Earth with a repeat time of 8 days Ultra-Wide ScanSAR 375 km Imaging of the complete acces range (375 km) in a single pass 6 bursts // 6 subswaths Swath width: 375 km Spatial resolution: 1m x ?m
    12. 12. - - - Rx Patt. ___ Tx Patt. ___ 2-way Patt. Pattern Design & Performance Azimuth pattern shape key influence on ScanSAR performance The Phase Spoiling technique is used to obtain the Tx pattern
    13. 13. UW ScanSAR: Azimuth Performance -24 dB 8,7 m 2,1 dB <ul><li>Az. Res. < 8,7 m </li></ul><ul><li>AASR < - 24 dB </li></ul><ul><li>Scalloping < 2,1 dB </li></ul>Azimuth Resolution Azimuth Ambiguity Signal Ratio Scalloping Stripmap: 1 m Scansar: 7 m gives high scalloping (>3.5dB)
    14. 14. UW ScanSAR: NESZ & RASR <ul><li>NESZ < - 22,6 dB </li></ul><ul><li>RASR < - 28 dB </li></ul>Noise Equivalent Sigma Zero Range Ambiguity Signal Ratio ground range resolution: 1 m - 28 dB - 22,6 dB
    15. 15. Summary and Conclusions <ul><li>Quad-Pol, Stripmap Mode </li></ul><ul><ul><li>12 subswaths, swath width: 20 - 50 km </li></ul></ul><ul><ul><li>Spatial resolution: 1 m x 1 m </li></ul></ul><ul><ul><li>NESZ < - 19.5 dB </li></ul></ul><ul><ul><li>RASR: Cross-Pol < - 19 dB , Co-Pol < - 27 dB </li></ul></ul><ul><ul><li>AASR < - 30.5 dB </li></ul></ul><ul><li>ScanSAR Mode: Ultra-Width Swath </li></ul><ul><ul><li>1 swath, swath width 375 km </li></ul></ul><ul><ul><li>Spatial resolution: 1 m x 9 m </li></ul></ul><ul><ul><li>NESZ < - 22.6 dB </li></ul></ul><ul><ul><li>RASR < - 28 dB </li></ul></ul><ul><ul><li>AASR < - 24 dB </li></ul></ul><ul><ul><li>Scalloping < 2.1 dB </li></ul></ul>

    ×