Ground-Based FMCW radar measurements: a summary of the NASA CLPX data H.P. Marshall Institute of...
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Transcript of Ground-Based FMCW radar measurements: a summary of the NASA CLPX data H.P. Marshall Institute of...
![Page 1: Ground-Based FMCW radar measurements: a summary of the NASA CLPX data H.P. Marshall Institute of Arctic and Alpine Research, Univ. of Colorado Gary Koh,](https://reader035.fdocuments.in/reader035/viewer/2022062413/5a4d1b947f8b9ab0599c2a4a/html5/thumbnails/1.jpg)
Ground-Based FMCW radar measurements: a summary of the NASA CLPX data
H.P. Marshall Institute of Arctic and Alpine Research, Univ. of ColoradoGary Koh, Cold Regions Research and Engineering Lab, New HampshireRick Forster, Department of Geography, University of Utah
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Brief FMCW Theory I
+ =
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Brief FMCW Theory II
• Linear frequency chirp transmitted (T)
• Received signal (R) “mixed” with transmitted wave before signal acquisition
• Recorded signal contains the sum and difference frequencies from T + R
• Frequency differences from reflectors linearly related to the distance to target
cd
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BT
dFTsw
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Windowed FFT, zero-padded, normalized by DC-coupling, power from
surface calibration
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Filter instrumentation-related signals
• Locations where mean of signal > 5x mean deviation found
• Mean trace at these depths subtracted from scan
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Depth Calibration
• Metal reflectors placed at known depths
• Accurate depth scale, will also be used to calculate attenuation
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Michigan Ridge, North Park, Feb 21,2003
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Berthud Pass, February 22, 2003
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Relationship of FMCW signal manual measurements
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Density profile vs radar
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In-situ Dielectric Properties
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In-situ Dielectric Properties II
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LSOS Feb 19, 2002, C-Band: 2-6 GHz
DRY SNOWPACK
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LSOS Feb 19, 2002, X-Band: 8-12 GHz
DRY SNOWPACK
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LSOS Feb 19, 2002, Ku-Band: 14-18 GHz
DRY SNOWPACK
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LSOS March 26, 2002, C-Band: 2-6 GHz
WET SNOWPACK
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LSOS March 26, 2002, X-Band: 8-12 GHz
WET SNOWPACK
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LSOS March 26, 2002, Ku-Band: 14-18 GHz
WET SNOWPACK
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Effect of incidence angle
oc
rc
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oeff P
PRR
4
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Effect of incidence angle II
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Conclusions • FMCW signal strongly related to
in-situ dielectric measurements• Resolution highest at Ku-Band,
but little penetration if wet• Incidence angle measurements
indicate surface scattering dominates below ~15 deg and volume scattering above 30
• Preliminary comparison with FMCW measurements at more narrow bandwidths encouraging
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Acknowledgements
NASA Earth System Science Fellowship
CRREL
Kelly Elder, Don Cline
Nate Mullheren