An Adaptive Window for Stare Processing of Delay Doppler Maps Ben - - PowerPoint PPT Presentation

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An Adaptive Window for Stare Processing of Delay Doppler Maps Ben - - PowerPoint PPT Presentation

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An Adaptive Window for Stare Processing of Delay Doppler Maps Ben Southwell & Andrew Dempster Australian Centre for Space Engineering Research GNSS-R Global Navigation Satellite System Reflectometry (GNSS-R) Bi-static Radar of

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An Adaptive Window for Stare Processing of Delay Doppler Maps

Ben Southwell & Andrew Dempster

Australian Centre for Space Engineering Research

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

GNSS-R

  • Global Navigation

Satellite System Reflectometry (GNSS-R)

  • Bi-static Radar of
  • pportunity
  • Cheap (M,V,P, $)
  • Covert
  • Over 100 Transmitters
  • Spaceborne

Scatterometry

Zavorotny, V. U., Gleason, S., Cardellach, E., & Camps, A. (2014). Tutorial on remote sensing using GNSS bistatic radar of

  • pportunity. IEEE Geoscience and Remote Sensing Magazine, 2(4), 8–45. https://doi.org/10.1109/MGRS.2014.2374220
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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

  • Assuming a strongly diffuse

scattering regime, the received power can be modeled with – extended radar cross section – system gain – receiver effects

  • DDM produced with ~1000 x

1ms integrations – limited coherence

GNSS-R

The Bistatic Radar Equation Surface Scenario Signal

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

  • Most points in the spatial

domain map ambiguously to delay, doppler domain

  • Specular zone is typically

processed for wind retrieval

  • AFL: f =
  • Signal Space Proc

Mapping to the DDM

AFL

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Stare Processing

Point on AFL

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Stare Processing

Example RD35 TD49 PRN 9 Collected by TDS-1

  • Similar to traditional

scatterometers

  • Resolution tradeoff
  • Generates a stare

profile

  • MSS estimated by

fitting simulated profile

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Stare Processing

Geometric Tracking and DDM sampling

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Stare Processing

DDM and WAF Footprint

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Variable Window Size

  • Iso-range lines becomes closer

as delay increases.

  • Iso-range gradient -> iso-Dop

gradient as delay increases

  • Inefficient spatial footprint

– effective area in BRE << bounding box

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Variable Window Stare Processing

DDM and WAF Footprint

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Impact on Resolution

  • Poor cross-track resolution

regardless of window at high delays as Iso-range -> iso-Doppler. I.e Inherent to the GNSS-r bi-static config

  • Cross track not as important

as along

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

SMN

  • Averaging Signal Power over

multiple d-D cells. More effective use of resolution cell

  • More measurements -> less

variance in stare profile

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Conclusions and Future Work

Stare Processing

  • Analogue to multi-look / spotlight SAR
  • footprint not constant
  • SNR is worse at high delays

Variable length window

  • footprint is more consistent
  • integral / resolution is larger
  • SNR improvement at non-zero delays

Future work

  • Extension to resolve wind direction

– Ambiguous Stare Points

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An Adaptive Window for Stare Processing of Delay Doppler Maps, Ben Southwell. International Global Navigation Satellite Systems Association, IGNSS Symposium 2018. Colombo Theatres, Kensington Campus, UNSW Australia 7 - 9 February 2018

Questions?