Isotropic RFI detection
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Transcript of Isotropic RFI detection
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Isotropic RFI detection
Jean-Luc Vergely (ACRI-ST)Claire Henocq (ACRI-ST)
Philippe Waldteufel (LATMOS)
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Introduction
Principal aims of this study :
Looking for strong isotropic source -> RFI
St1, A3 and A4 analysis.
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Data setData set to be used
2010 and 2011 reprocessed data.
Philosophy:
-> use L1c browse products for global analysis: source detection on ocean and land targets.
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Data set
Land/ocean L1c browse products
L1c browse products over two years (2010 and 2011) : - four polarizations (in FP mode) at the same
geometry- TB at antenna level- TB at 42.5° incidence- TB errors
Allow global analysis on 5 FOV zones
Zone 1 Zone 2
Zone 3
Zone 4 Zone 5
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Introduction
St1,A3 or A4 emission
• Is the signal observed on descending and ascending orbits ?
• Is the signal isotropic?
• Is the signal variable or constant ?
• Is the signal spatially coherent ?
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Isotropic source
Detected in the 5 zones in ascending and descending -> good azimuth coverage.
Normalization to be done because of using zones affected by different OTT correction.
Applying a threshold.
St1 and A4
For A3 : ascending and descending zone 3
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St1 isotropic sourceIsotropic source detection
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St1 isotropic sourceIsotropic source detection
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St1 isotropic source
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A4 isotropic sourcesThreshold of 3 K
Only RFI …
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A4 isotropic sourceIsotropic source detection
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A3 asc/desc sourcesThreshold of 7 K
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A3 isotropic sourceIsotropic source detection
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Principal conclusions
Looking for RFI from St1, A3 and A4 SMOS measurements: isotropic sources
For RFI detection : do not use A4 (correlated with A3).
Only few isotropic sources have been detected. Constant isotropic source for St1 could be RFI.
Distinction between sources and Gibbs effect to be done.
-> further works : play with different thresholds (adaptation of the threshold according to the target (ocean or land).